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PTD - 194

Test Directory - Carbamazepine



Clinical Indications

Carbamazepine (CBZ) is an anti-epileptic drug, used for tonic-clonic seizures. Monitoring may assist dose changes.  Concomitant therapy may affect levels by inducing liver metabolism.

Request Form

Combined Pathology Blood form (Yellow/Black)


On request

Specific Criteria

Patients on carbamazepine therapy

Patient Preparation

Time of collection is not critical but due to the relatively short half-life CBZ levels can vary quite markedly across the dosage interval; collection at a similar time, usually before next dose, may help long-term monitoring.

Turnaround Time

Same day (Monday to Friday)




1 ml


Yellow top (SST) tube or

Paediatric orange top (lithium-heparin)

Causes for Rejection

Not meeting specific criteria for analysis.

Target  Range

4 - 12 mg/L

Toxicity (Interpretation)

Dizziness and visual disturbances are increasingly frequent at CBZ levels above 10 mg/L. A generalized erythematous rash may occur in 3-5% of patients. Long-term effects are few but water retention and hyponatraemia may occur as a late complication

Unit Conversion

To convert from umol/L to mg/L multiply by 0.236


An information sheet is available from the National Poisons Service (Toxbase)

Lab. Handling

Processing: Aliquot (MPA) and place in c311 rack for analysis, store at 4C in separating fridge if not analysed (CB39).

Version 1.0 / April 2014                                                                                                          Approved by: Consultant Biochemist