Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
Clozapine is an atypical antipsychotic used to treat schizophrenia resistant to conventional therapy. Because of the risk of agranulocytosis, white blood cell counts (WBC) are monitored weekly in the early stages of therapy and monthly thereafter.
It is recommended that therapy is withheld if the WBC is less than 3,500 mm-3 and abandoned if the WBC falls below 3000 mm-3 or the granulocyte count below 1,500 mm-3. Side-effects of clozapine include lethargy, hypersalivation, constipation and somnolence. There is a risk of hypotension and seizure at higher doses. A single dose of 300-400 mg may be life-threatening in a clozapine naïve subject. Clozapine is metabolised by N-demethylation, hydroxylation and N-oxidation. The N-demethylated metabolite, norclozapine, is present in plasma at similar concentrations to the parent compound, but has a longer plasma half-life. Plasma clozapine concentrations of 0.35 mg/L and above have been associated with a good response, with the risk of convulsions increasing above 1.0 mg/L.
Specimen container paediatric:
EDTA whole blood
Specimen container adult:
EDTA whole blood
Minimum volume paediatric:
2 mL blood
Minimum volume adult:
2 mL blood
Special requirements:
Pre-dose or trough sample
Transport requirements:
Post at ambient temperature
Reference ranges:
0.35 – 0.50 mg/L
Other info:
Serum (plain tube only) or plasma samples also acceptable.