Isoniazid

Alternative names, keywords

N-acetyl isoniazid (inactive metabolite)

Samples required

Fluoride oxalate blood (grey cap, 2 mL tube). Smaller tubes are available for paediatric samples.

Post dose sample recommended, taken 2 hours after the end of administration (and/or 6 hours if monitoring absorption). 

Test indications

Checking if adequate concentrations are being reached during therapy.

N-Acetyl isoniazid is an indicator of the rate of isoniazid metabolism to the inactive form.

Reference range

Isoniazid post dose: 3.0 – 5.0 mg/L

N-Acetyl Isoniazid post dose: not applicable

Turnaround time

Referral lab quotes turnaround time of less than 3 working days*, however additional time must be allowed for packing, dispatch and delivery of sample, and return and processing of results.

*samples are analysed on day of receipt if before 3pm, Monday to Friday.

Enquiries

Biochemistry (Referrals)