Clozapine

Test Code

CZNZ

Quest Code

1769

CPT Codes
80159

Includes

Clozapine and Norclozapine

Preferred Specimen

2 mL serum collected in a red-top tube (no gel)

Minimum Volume

1 mL

Other Acceptable Specimens

Plasma collected in: EDTA (lavender-top) tube, sodium heparin (green-top) tube, or lithium heparin (green-top) tube

Transport Temperature

Frozen

Specimen Stability

Room temperature: 24 hours
Refrigerated: 5 days
Frozen: 30 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Gross hemolysis • Gel barrier/Serum separator tube (SST)

Methodology
Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)

Setup Schedule

Set up: Tues-Sat; Report available: 1-3 days

Reference Range

Norclozapine

25-400 mcg/L

Clozapine
The therapeutic response begins to appear at 100 mcg/L
Refractory schizophrenia appears to require a therapeutic concentration of at least 350 mcg/L (trough, at steady state).
Toxic range: >900 mcg/L

Clinical Significance

Clozapine is an atypical antipsychotic agent. Norclozapine has minimal therapeutic activity.

Performing Laboratory
Quest Diagnostics Valencia Nichols Institute
27027 Tourney Road
Valencia, CA 91355-5386

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.