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Beta trace protein
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Beta trace protein (BTP) |
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Also known as |
Prostaglandin D2 synthase |
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Assay Information |
Beta trace protein (BTP) is a low molecular weight protein (24kDa) also known as prostaglandin D2 synthase. BTP is mainly synthesized in the central nervous system by glial cells and the choroid plexus and forms one of the principle constituents of cerebrospinal fluid (CSF). BTP concentrations are therefore much higher in CSF than in serum or plasma so it is a useful marker for detecting CSF leakage in fluids such as nose or ear secretions. In the Neuroscience Labs, BTP is used as a first line test for ?CSF fluids. Beta-2-transferrin is reserved as a second line test for specimens that are unsuitable for BTP analysis, or those that give an equivocal BTP result.
Virtually all circulating BTP is filtered by the kidneys therefore the plasma concentration is mainly dependent on the glomerular filtration rate. Serum BTP can therefore also be used as a marker of renal function in some scenarios. However the Neurosciences Laboratories do not use the assay for this purpose.
BTP is analysed by nephelometry. The reagent contains polystyrene particles coated with antibodies to human BTP. When a sample containing BTP is added, the particles aggregate and scatter a beam of light passed through the sample. The intensity of the scattered light is proportional to the concentration of BTP in the sample.
Note - Beta Trace Protein (BTP) is the first-line screening test. Beta 2 transferrin (B2T) will be performed when sample is unsuitable for BTP e.g. small volume, too viscous, sample haemolysed etc. B2T will also be performed if BTP result is equivocal.
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Specimen Type(s) & Minimum Volume |
Fluid / secretion – 0.2 mL Note 1 – serum is useful to aid interpretation, but do not delay sending fluid if serum is not available. Note 2 – please centrifuge bloodstained or contaminated fluids as soon as possible and send supernatant. Please ring if further advice required. |
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Cost |
£42.00
Beta trace protein and/or beta 2 transferrin will be analysed depending on sample/results. Cost fixed regardless of assay(s) performed.
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Transport |
First class post
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Frequency of Analysis/Turnaround Time |
2 Working Days |
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Assay Method |
Nephelometry
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Reference Range & Units |
<0.7 mg/L |
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Factors Affecting Performance of Examination
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Renal insufficiency Patients with normal pressure hydrocephalus or meningitis. Over dilution with other bodily fluids. Blood stained samples |
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Related Tests |
Beta-2 transferrin Note - Beta Trace Protein (BTP) is the first-line screening test. |
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Accredited Assay |
UKAS 8642
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External Quality Assurance (EQA) |
UK NEQAS for CSF B2 Transferrin/Beta Trace Protein |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net
Telephone: 0151 5563262
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References |
Bernasconi L, Pȍtzl T, Steuer C, et al. Retrospective validation of a β-trace protein interpretation algorithm for the diagnosis of cerebrospinal fluid leakage. Clin Chem Lab Med. 2017; 55(4): 554-560. Meco C, Oberascher G, Arrer E, Moser G and Albegger K. Beta-trace protein test: new guidelines for the reliable diagnosis of cerebrospinal fluid fistula. Otolaryngol Head Neck Surg. 2003; 129(5): 508-17. Kleine TO, Damm T, Althaus H. Quantification of beta-trace protein and detection of transferrin isoforms in mixtures of cerebral fluid and blood serum as models of rhinorrhea and ottorrhea diagnosis. Fresenius J Anal Chem. 2000; 366: 382-6. |
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Date last updated |
Tuesday, 17 August 2021 |
Beta-2-Transferrin
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Beta-2 transferrin |
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Also known as |
Asialo-transferrin Note – beta 2 transferrin is sometimes called Tau protein. This is not recommended to prevent confusion with the dementia marker. |
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Assay Information |
The assay enables the detection of beta 2 transferrin (asialo-transferrin), to determine the presence of CSF in rhinorrhoea and otorrhoea fluids.
The method separates transferrin and asialo-transferrin by electrophoresis on a high-resolution agarose gel, followed by transfer onto nitrocellulose membrane. Following blocking, the membrane is incubated with goat anti-human transferrin and then, following washing, with peroxidase-conjugated anti-goat IgG. The results are visualised by addition of a chromagen.
Note - Beta Trace Protein (BTP) is the first-line screening test. Beta 2 transferrin (B2T) will be performed when sample is unsuitable for BTP e.g. small volume, too viscous, sample haemolysed etc. B2T will also be performed if BTP result is equivocal.
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Specimen Type(s) & Minimum Volume |
Fluid / secretion – 0.2 mL Serum 0.2 mL Note 1 – serum is useful to aid interpretation, but do not delay sending fluid if serum is not available. Note 2 – please centrifuge bloodstained or contaminated fluids as soon as possible and send supernatant. Please ring if further advice required. |
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Cost |
£42.00
Beta trace protein and/or beta 2 transferrin will be analysed depending on sample/results. Cost fixed regardless of assay(s) performed. |
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Transport |
First class post
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Frequency of Analysis/Turnaround Time |
2 Working Days |
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Assay Method |
Electrophoresis followed by immunoblotting
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Reference Range & Units |
Apart from CSF, body fluids do not normally contain beta 2 transferrin. |
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Factors Affecting Performance of Examination
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Heavily blood stained samples Bacterial contamination |
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Related Tests |
Beta trace protein Note - Beta Trace Protein (BTP) is the first-line screening test. |
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Accredited Assay |
UKAS 8642 |
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External Quality Assurance (EQA) |
UK NEQAS for CSF B2 Transferrin/Beta Trace Protein |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net
Telephone: 0151 5563262
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References |
Keir et al (1992) Immunoblotting of transferrin in the identification of cerebrospinal fluid otorrhoea and rhinorrhoea. Ann Clin Biochem 1992: 29: 210-213 Zervos TM, Macki M, Cook B, Schultz LR, Rock JP, Craig JR. Beta-2 transferrin is detectable for 14 days whether refrigerated or stored at room temperature. International forum of Allergy and Rhinology 2018; XX: 1-4. |
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Date last updated |
Tuesday, 17 August 2021 |
Carbamazepine (Tegretol)
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Carbamazepine |
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Also known as |
CBZ, Tegretol |
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Assay Information |
Please contact laboratory for details |
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Specimen Type(s) & Minimum Volume |
Serum 100 µL |
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Cost |
£12.50 |
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Storage/Transport |
Store at 4ºC Transport by post, ambient temperature
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Frequency of Analysis/Turnaround Time |
2 working days Same day analysis is usually possible by prior arrangement with the lab, and if the sample is received before 12 noon.
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Assay Method |
UPLC-MS/MS
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Reference Range & Units |
4-12 mg/L |
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Factors Affecting Performance of Examination |
No known analytical interferents |
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Related Tests |
This is the pharmacologically active metabolite of carbamazepine, which may be increased with concurrent use of certain other anticonvulsants. |
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Accredited Assay |
8642 |
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External Quality Assurance (EQA) |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net Telephone: 0151 5563262 |
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References |
Antiepileptic drugs – best practice guidelines for therapeutic drug monitoring: A position paper by the sub-commission on therapeutic drug monitoring, ILAE Commission on Therapeutic Strategies. Patsalos et al. Epilepsia 2008; 49 (7): 1239-1276. |
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Date last updated |
12/08/2021 |
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Carbamazepine-10,11-epoxide
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Carbamazepine epoxide |
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Also known as |
Carbamazepine epoxide |
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Assay Information |
Please contact laboratory for details |
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Specimen Type(s) & Minimum Volume |
Serum 100 µL |
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Cost |
£12.50 |
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Storage/Transport |
Store at 4ºC Transport by post, ambient temperature
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Frequency of Analysis/Turnaround Time |
2 working days Same day analysis is usually possible by prior arrangement with the lab, and if the sample is received before 12 noon.
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Assay Method |
UPLC-MS/MS
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Reference Range & Units |
An evidence based target range for carbamazepine-10,11-epoxide has not been fully validated. However, steady state concentrations are expected in the range 0.4-4.0 mg/L, and toxic symptoms have been reported when concentrations reach 8 mg/L. |
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Factors Affecting Performance of Examination |
No known analytical interferents |
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Related Tests |
Carbamazepine |
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Accredited Assay |
8642 |
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External Quality Assurance (EQA) |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net Telephone: 0151 5563262 |
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References |
Antiepileptic drugs – best practice guidelines for therapeutic drug monitoring: A position paper by the sub-commission on therapeutic drug monitoring, ILAE Commission on Therapeutic Strategies. Patsalos et al. Epilepsia 2008; 49 (7): 1239-1276.
https://www.mayocliniclabs.com/test-catalog (accessed 16/08/2021) |
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Date last updated |
16/08/2021 |
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CSF bilirubin
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CSF bilirubin (Xanthochromia) |
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Assay Information |
Following haemorrhage into the CSF, red blood cells undergo lysis and phagocytosis; the liberated oxyhaemoglobin is converted in-vivo in a time-dependant manner into bilirubin and sometimes methaemoglobin. Of these pigments, only bilirubin arises solely from in-vivo conversion. Oxyhaemoglobin (and possibly methaemoglobin) may both be produced in-vivo and in-vitro following a traumatic tap. Spectrophotometry is of particular value in the investigation of a CSF with an increased red cell count as there is no other reliable way of distinguishing between SAH and a traumatic tap. It is also of value in the investigation of CSF with a normal red cell count from a patient presenting several days after an event by which time the cells may no longer be present. The presence of excess bilirubin in the CSF is calculated by measuring its Net Bilirubin Absorbance (NBA).
CT scan is the primary method of detecting SAH. However, spectrophotometry of CSF is a useful second line test in patients presenting at late time points or when clinical suspicion is still high following a negative CT scan.
Only patients with a negative or equivocal CT result and also with a history suggestive of SAH should be considered for LP to rule out SAH by spectrophotometry. Furthermore the LP should be at least 12hrs-post event, LP’s less than 12hrs are not diagnostic when detecting bilirubin. |
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Specimen Type(s) & Minimum Volume |
CSF – 0.3 mL Note - Minimum volume required for assay is approximately 80uL. |
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Cost |
£21.00 |
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Transport |
First class post (protected from light)
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Frequency of Analysis/Turnaround Time |
2 Hours |
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Assay Method |
Spectrophotometry |
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Reference Range & Units
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Net Bilirubin Absorbance ≤0.007 AU Net Oxyhaemoglobin Absorbance ≤0.02 AU |
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Factors Affecting Performance of Examination
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Failure to protect from light Time of sampling must be >12 hours and <14 days post event. Delayed analysis. |
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Related Tests |
Not applicable |
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Accredited Assay |
UKAS 8642
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External Quality Assurance (EQA) |
UK NEQAS for immunology scheme for CSF Haem pigments |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net Telephone: 0151 5563262
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References |
Revised National Guidelines for the analysis of cerebrospinal fluid for bilirubin in suspected subarachnoid haemorrhage. Ann Clin Biochem 2008; 45: 238-244
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Date last updated |
Tuesday, 17 August 2021 |
CSF IgG
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CSF Immunoglobulin G (IgG) |
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Assay Information |
Immunoglobulins are formed by plasma cells as a humoral response to contact of the immune system with antigens. Quantitative determination of the immunoglobulins can provide important information on the humoral immune status. Decreased serum immunoglobulin concentrations occur in primary immunodeficiency conditions as well as in secondary immune insufficiencies. Increased serum immunoglobulin concentrations occur due to polyclonal or Oligoclonal Ig proliferation. Monoclonal immunoglobulinaemia requires detailed differential diagnostic investigations in addition to quantitative determination. Local immune reactions within the CNS result in elevated immunoglobulin levels particularly IgG in the CSF.
Proteins contained in human body fluids form immune complexes in an immunochemical reaction with specific antibodies. These complexes scatter a beam of light passed through the sample. The intensity of the scattered light is proportional to the concentration of the relevant protein in the sample. The result is evaluated by comparison with a standard of known concentration. |
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Specimen Type(s) & Minimum Volume |
CSF - 0.3mL |
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Cost |
CSF IgG is analysed as part of an oligoclonal bands request. Contact laboratory if just CSF IgG required.
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Transport |
First class post
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Frequency of Analysis/Turnaround Time |
CSF IgG analysed daily. Oligoclonal band assay TAT is 5 working days. |
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Assay Method |
Nephelometry
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Reference Range & Units |
CSF IgG <0.034 g/L |
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Factors Affecting Performance of Examination
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None |
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Related Tests |
Oligoclonal bands CSF Index (Calculated value providing indication of likelihood of intrathecal IgG synthesis) |
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Accredited Assay |
UKAS 8642
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External Quality Assurance (EQA) |
UK NEQAS for immunology scheme for CSF proteins & biochemistry |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net
Telephone: 0151 5563262
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References |
To follow
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Date last updated |
Tuesday, 17 August 2021 |
CSF Lactate
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LACTATE (CSF) |
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Assay Information |
Lactate levels in CSF are increased in bacterial meningitis, hypocapnia hydrocephalus, brain abscesses, cerebral ischemia and other conditions associated with reduced oxygenation of the brain and/or increased intracranial pressure. Measurement of CSF lactate helps in differential diagnosis between bacterial and viral infections. Lactate is oxidized to pyruvate and hydrogen peroxide by lactate oxidase (LOD). In the presence of peroxidase (POD), hydrogen peroxide reacts with H donor and 4-aminoantipyrine (4-AAP) to form a red quinoneimine dye. Colourimetric assay. L-lactate is oxidized to pyruvate by the specific enzyme lactate oxidase (LOD). Peroxidase (POD) is used to generate a colored dye using the hydrogen peroxide generated in the first reaction. The intensity of the color formed is directly proportional to the L-lactate concentration. It is determined by measuring the increase in absorbance.
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Specimen Type(s) & Minimum Volume |
CSF - 0.3mL |
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Cost |
£17.30
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Transport |
First class post
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Frequency of Analysis/Turnaround Time |
Daily. Turnaround time 2 hours. |
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Assay Method |
Colorimetric assay
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Reference Range & Units |
1.1 – 2.4 mmol/L
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Factors Affecting Performance of Examination
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Ensure sample is acellular. Please centrifuge and send supernatant if cells present. |
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Related Tests |
None |
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Accredited Assay |
UKAS 8642
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External Quality Assurance (EQA) |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net
Telephone: 0151 5563262
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References |
To follow |
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Date last updated |
15th August 2021
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Free Phenytoin (Dilantin)
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Free phenytoin |
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Also known as |
Unbound phenytoin, Dilantin, Epanutin |
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Assay Information |
Includes measurement of total phenytoin. Please contact laboratory for details.
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Specimen Type(s) & Minimum Volume |
Serum 500 µL |
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Cost |
£25.00 |
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Storage/Transport |
Store at 4ºC Transport by post, ambient temperature
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Frequency of Analysis/Turnaround Time |
2 working days Same day analysis is usually possible by prior arrangement with the lab, and if the sample is received before 12 noon.
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Assay Method |
UPLC-MS/MS
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Reference Range & Units |
0.5-2 mg/L This range is 10% of the total phenytoin range quoted by the National Pathology Harmony Group (www.pathologyharmony.co.uk)
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Factors Affecting Performance of Examination |
No known analytical interferents |
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Related Tests |
Phenytoin |
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Accredited Assay |
8642 |
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External Quality Assurance (EQA) |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net Telephone: 0151 5563262 |
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References |
Antiepileptic drugs – best practice guidelines for therapeutic drug monitoring: A position paper by the sub-commission on therapeutic drug monitoring, ILAE Commission on Therapeutic Strategies. Patsalos et al. Epilepsia 2008; 49 (7): 1239-1276. |
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Date last updated |
16/08/2021 |
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Lamotrigine (Lamictal)
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Lamotrigine |
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Also known as |
Lamictal |
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Assay Information |
Please contact laboratory for details.
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Specimen Type(s) & Minimum Volume |
Serum 100 µL |
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Cost |
£17.00 |
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Storage/Transport |
Store at 4ºC Transport by post, ambient temperature
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Frequency of Analysis/Turnaround Time |
2 working days Same day analysis is usually possible by prior arrangement with the lab, and if the sample is received before 12 noon.
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Assay Method |
UPLC-MS/MS
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Reference Range & Units |
3-15 mg/L |
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Factors Affecting Performance of Examination |
No known analytical interferents |
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Related Tests |
None |
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Accredited Assay |
8642 |
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External Quality Assurance (EQA) |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net Telephone: 0151 5563262 |
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References |
Antiepileptic drugs – best practice guidelines for therapeutic drug monitoring: A position paper by the sub-commission on therapeutic drug monitoring, ILAE Commission on Therapeutic Strategies. Patsalos et al. Epilepsia 2008; 49 (7): 1239-1276. |
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Date last updated |
16/08/2021 |
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Levetiracetam (Keppra)
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Levetiracetam |
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Also known as |
Keppra |
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Assay Information |
Please contact laboratory for details |
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Specimen Type(s) & Minimum Volume |
Serum 100 µL |
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Cost |
£17.00 |
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Storage/Transport |
Store at 4ºC Transport by post, ambient temperature
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Frequency of Analysis/Turnaround Time |
2 working days Same day analysis is usually possible by prior arrangement with the lab, and if the sample is received before 12 noon.
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Assay Method |
UPLC-MS/MS
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Reference Range & Units |
12-46 mg/L |
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Factors Affecting Performance of Examination |
No known analytical interferents |
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Related Tests |
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Accredited Assay |
8642 |
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External Quality Assurance (EQA) |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net Telephone: 0151 5563262 |
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References |
Antiepileptic drugs – best practice guidelines for therapeutic drug monitoring: A position paper by the sub-commission on therapeutic drug monitoring, ILAE Commission on Therapeutic Strategies. Patsalos et al. Epilepsia 2008; 49 (7): 1239-1276. |
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Date last updated |
16/08/2021 |
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Midazolam
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Midazolam |
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Also known as |
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Assay Information |
Please contact laboratory for details |
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Specimen Type(s) & Minimum Volume |
Serum 100 µL |
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Cost |
£50.00 |
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Storage/Transport |
Store at 4ºC Transport by post, ambient temperature.
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Frequency of Analysis/Turnaround Time |
1 working day Same day analysis is usually possible by prior arrangement with the lab, and if the sample is received before 12 noon.
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Assay Method |
UPLC-MS/MS
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Reference Range & Units |
If the serum midazolam concentration is being measured as part of brain stem death testing, no further testing should be undertaken unless the midazolam concentration is less than 10µg/L.
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Factors Affecting Performance of Examination |
No known analytical interferents |
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Related Tests |
None |
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Accredited Assay |
8642 |
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External Quality Assurance (EQA) |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net Telephone: 0151 5563262 |
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References |
Academy of Medical Royal Colleges. A code of practice for the diagnosis and confirmation of death. 2008.
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Date last updated |
16/08/2021 |
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Oligoclonal bands
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Oligoclonal bands (CSF) |
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Assay Information |
Multiple sclerosis (MS) is an autoimmune condition in which the immune system attacks the CNS, leading to demyelination. It causes numerous physical symptoms, and often progresses to physical and cognitive disability. Disease onset usually occurs in young adults, is more common in women, and has a prevalence that ranges between 2 and 150 per 100,000 depending on the country or specific population.
MS affects the areas of the brain and spinal cord known as the white matter, specifically, destroying oligodendrocytes which are the cells responsible for creating and maintaining the myelin sheath, which helps the neurons carry electrical signals. MS results in a thinning or complete loss of myelin and, less frequently, the cutting (transection) of the neurons axons. When the myelin is lost, the neurons can no longer effectively conduct their electrical signals. The name “multiple sclerosis” refers to the scars (scleroses - better known as plaques or lesions) in the white matter. Loss of myelin in these lesions causes some of the symptoms, which vary widely depending upon which signals are interrupted. However, more advanced forms of imaging are now showing that much of the damage happens outside these regions. Almost any neurological symptom can accompany the disease.
Immunoglobulins can be separated according to their isoelectric points within a pH gradient that is generated by electrophoresis and stabilised using zwitterionic ampholytes (Pharmalytes). Once separated the proteins are passively transferred onto a nitrocellulose membrane. Unoccupied protein binding sites are blocked with non-fat milk. Immunoglobulin G is identified using a single antibody detection system, using a goat anti-human IgG peroxidase conjugate antibody. Bound peroxidase activity is detected by a chromogenic reaction utilising amino-ethyl-carbazole and 30% v/v Hydrogen peroxide. This results in a pink-brown precipitate that corresponds to the separated immunoglobulin G from the original sample.
Isoelectric focusing is used by the Neuroimmunology laboratory to detect oligoclonal IgG responses in cerebrospinal fluid (CSF) and serum. The principal purpose of the examination is to identify those patients that have oligoclonal bands in the CSF only, with no corresponding bands in paired serum. The oligoclonal bands (OCB) are thus local to the central nervous system, and so are termed locally or intrathecally synthesised OCBs.
The detection of OCB is a sensitive and specific marker for intrathecal synthesis of IgG which is present in a large proportion of patients with demyelinating diseases (>90%). In multiple sclerosis the sensitivity of OCB is thought to be >95%. Oligoclonal bands are also found in a number of other inflammatory and infectious diseases of the CNS, including paraneoplastic disease and encephalitis, although a few weak oligoclonal bands may also be present in the serum as well as CSF in such cases. |
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Specimen Type(s) & Minimum Volume |
CSF – 0.3 mL Serum – 0.3 mL Note – CSF and serum samples required for interpretation |
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Cost |
£38.00
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Transport |
First class post
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Frequency of Analysis/Turnaround Time |
5 working days |
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Assay Method |
Isoelectric focusing
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Reference Range & Units
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A normal sample will contain no oligoclonal bands. |
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Factors Affecting Performance of Examination
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Grossly haemolysed samples CSF and serum should be ideally be taken on same day. |
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Related Tests |
CSF IgG CSF Index (Calculated value providing indication of likelihood of intrathecal IgG synthesis) |
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Accredited Assay |
UKAS 8642
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External Quality Assurance (EQA) |
UKNEQAS CSF oligoclonal bands |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net Telephone: 0151 5563262
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References |
Keir G et al. Isoelectric Focusing of Cerebrospinal Fluid Immunoglobulin G: An Annotated Update. Ann Clin Biochem 1990; 27:436-443
Andersson M et al. Cerebrospinal fluid in the diagnosis of multiple sclerosis: a consensus report. Journal of Neurology, Neurosurgery and Psychiatry 1994; 57:897-902
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Date last updated |
Tuesday, 17 August 2021 |
Phenobarbital (Luminal)
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Phenobarbital |
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Also known as |
Luminal |
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Assay Information |
Please contact laboratory for details
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Specimen Type(s) & Minimum Volume |
Serum - 0.1mL |
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Cost |
£12.50
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Transport |
Store at 4ºC Transport by post, ambient temperature.
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Frequency of Analysis/Turnaround Time |
2 working days Same day analysis is usually possible by prior arrangement with the lab, and if the sample is received before 12 noon. |
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Assay Method |
Liquid chromatography tandem mass spectrometry |
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Reference Range & Units |
10-40 mg/L |
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Factors Affecting Performance of Examination
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No known interferences |
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Related Tests |
None |
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Accredited Assay |
UKAS 8642
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External Quality Assurance (EQA) |
LGC Therapeutic drugs scheme antiepileptic drugs mixture |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net
Telephone: 0151 5563262
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References |
Antiepileptic drugs – best practice guidelines for therapeutic drug monitoring: A position paper by the sub-commission on therapeutic drug monitoring, ILAE Commission on Therapeutic Strategies. Patsalos et al. Epilepsia 2008; 49 (7): 1239-1276. |
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Date last updated |
Tuesday, 17 August 2021 |
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Phenytoin (Dilantin)
|
Phenytoin |
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Also known as |
Dilantin, Epanutin |
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Assay Information |
Please contact laboratory for details.
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Specimen Type(s) & Minimum Volume |
Serum 100 µL |
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Cost |
£12.50 |
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Storage/Transport |
Store at 4ºC Transport by post, ambient temperature
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Frequency of Analysis/Turnaround Time |
2 working days Same day analysis is usually possible by prior arrangement with the lab, and if the sample is received before 12 noon.
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Assay Method |
UPLC-MS/MS
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Reference Range & Units |
5-20 mg/L |
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Factors Affecting Performance of Examination |
No known analytical interferents |
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Related Tests |
Free phenytoin |
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Accredited Assay |
8642 |
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External Quality Assurance (EQA) |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net Telephone: 0151 5563262 |
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References |
Antiepileptic drugs – best practice guidelines for therapeutic drug monitoring: A position paper by the sub-commission on therapeutic drug monitoring, ILAE Commission on Therapeutic Strategies. Patsalos et al. Epilepsia 2008; 49 (7): 1239-1276. |
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Date last updated |
16/08/2021 |
Pregabalin (Lyrica)
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Pregabalin |
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Also known as |
Lyrica |
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Assay Information |
Please contact laboratory for details.
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Specimen Type(s) & Minimum Volume |
Serum 100 µL |
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Cost |
£30.00 |
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Storage/Transport |
Store at 4ºC Transport by post, ambient temperature
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Frequency of Analysis/Turnaround Time |
5 working days Same day analysis is usually possible by prior arrangement with the lab, and if the sample is received before 12 noon.
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Assay Method |
UPLC-MS/MS
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Reference Range & Units |
No evidence based target range is available for pregabalin. However, results are expected in the range of 2.8-8.3 mg/L.
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Factors Affecting Performance of Examination |
No known analytical interferents |
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Related Tests |
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Accredited Assay |
8642 |
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External Quality Assurance (EQA) |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net Telephone: 0151 5563262 |
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References |
Antiepileptic drugs – best practice guidelines for therapeutic drug monitoring: A position paper by the sub-commission on therapeutic drug monitoring, ILAE Commission on Therapeutic Strategies. Patsalos et al. Epilepsia 2008; 49 (7): 1239-1276. |
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Date last updated |
16/08/2021 |
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Topiramate (Topamax)
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Topiramate |
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Also known as |
Topamax |
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Assay Information |
Please contact laboratory for details.
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Specimen Type(s) & Minimum Volume |
Serum 100 µL |
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Cost |
£30.00 |
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Storage/Transport |
Store at 4ºC Transport by post, ambient temperature
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Frequency of Analysis/Turnaround Time |
5 working days Same day analysis is usually possible by prior arrangement with the lab, and if the sample is received before 12 noon.
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Assay Method |
UPLC-MS/MS
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Reference Range & Units |
5-20 mg/L.
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Factors Affecting Performance of Examination |
No known analytical interferents |
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Related Tests |
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Accredited Assay |
8642 |
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External Quality Assurance (EQA) |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net Telephone: 0151 5563262 |
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References |
Antiepileptic drugs – best practice guidelines for therapeutic drug monitoring: A position paper by the sub-commission on therapeutic drug monitoring, ILAE Commission on Therapeutic Strategies. Patsalos et al. Epilepsia 2008; 49 (7): 1239-1276. |
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Date last updated |
16/08/2021 |
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Valproate (Epilim)
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Valproic acid |
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Also known as |
Sodium valproate, Epilim |
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Assay Information |
Please contact laboratory for details.
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Specimen Type(s) & Minimum Volume |
Serum 100 µL |
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Cost |
£12.50 |
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Storage/Transport |
Store at 4ºC Transport by post, ambient temperature
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Frequency of Analysis/Turnaround Time |
2 working days Same day analysis is usually possible by prior arrangement with the lab, and if the sample is received before 12 noon.
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Assay Method |
UPLC-MS/MS
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Reference Range & Units |
No evidence based target range available |
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Factors Affecting Performance of Examination |
No known analytical interferents |
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Related Tests |
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Accredited Assay |
8642 |
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External Quality Assurance (EQA) |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net Telephone: 0151 5563262 |
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References |
Antiepileptic drugs – best practice guidelines for therapeutic drug monitoring: A position paper by the sub-commission on therapeutic drug monitoring, ILAE Commission on Therapeutic Strategies. Patsalos et al. Epilepsia 2008; 49 (7): 1239-1276. |
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Date last updated |
16/08/2021 |
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Xanthochromia
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CSF bilirubin (Xanthochromia) |
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Assay Information |
Following haemorrhage into the CSF, red blood cells undergo lysis and phagocytosis; the liberated oxyhaemoglobin is converted in-vivo in a time-dependant manner into bilirubin and sometimes methaemoglobin. Of these pigments, only bilirubin arises solely from in-vivo conversion. Oxyhaemoglobin (and possibly methaemoglobin) may both be produced in-vivo and in-vitro following a traumatic tap. Spectrophotometry is of particular value in the investigation of a CSF with an increased red cell count as there is no other reliable way of distinguishing between SAH and a traumatic tap. It is also of value in the investigation of CSF with a normal red cell count from a patient presenting several days after an event by which time the cells may no longer be present. The presence of excess bilirubin in the CSF is calculated by measuring its Net Bilirubin Absorbance (NBA).
CT scan is the primary method of detecting SAH. However, spectrophotometry of CSF is a useful second line test in patients presenting at late time points or when clinical suspicion is still high following a negative CT scan.
Only patients with a negative or equivocal CT result and also with a history suggestive of SAH should be considered for LP to rule out SAH by spectrophotometry. Furthermore the LP should be at least 12hrs-post event, LP’s less than 12hrs are not diagnostic when detecting bilirubin. |
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Specimen Type(s) & Minimum Volume |
CSF – 0.3 mL Note - Minimum volume required for assay is approximately 80uL. |
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Cost |
£21.00 |
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Transport |
First class post (protected from light)
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Frequency of Analysis/Turnaround Time |
2 Hours |
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Assay Method |
Spectrophotometry |
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Reference Range & Units
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Net Bilirubin Absorbance ≤0.007 AU Net Oxyhaemoglobin Absorbance ≤0.02 AU |
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Factors Affecting Performance of Examination
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Failure to protect from light Time of sampling must be >12 hours and <14 days post event. Delayed analysis. |
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Related Tests |
Not applicable |
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Accredited Assay |
UKAS 8642
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External Quality Assurance (EQA) |
UK NEQAS for immunology scheme for CSF Haem pigments |
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Further Information |
email: wcf-tr.neurobiochemistry@nhs.net Telephone: 0151 5563262
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References |
Revised National Guidelines for the analysis of cerebrospinal fluid for bilirubin in suspected subarachnoid haemorrhage. Ann Clin Biochem 2008; 45: 238-244
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Date last updated |
Monday, 06 September 2021 |
Page last updated: 23 May 2023