Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Therapeutic Drug Monitoring
Clozapine: >350 ng/mL; Clozapine & Norclozapine: >450 ng/mL.
* Reference ranges may change over time. Please refer to the original patient report when evaluating results.
Days Test Performed
Monday - Friday
3 - 5 days
Soft Order Code
Clozapine (Clozaril), Level
Update Type: Reference range changed
Updated Date: 06/03/2020
Mayo CLZ (61657)
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Offsite Collection Instructions
Collect specimen in a red top tube; do not use SST tube. Centrifuge, aliquot serum into a plastic container and refrigerate.
SST tube not acceptable.
1.0 mL serum
0.6 mL serum
Clozapine is an antipsychotic agent. Peak clozapine concentrations are reached in 1-6 hours following oral dosage. Elimination half-life is 4-16 hours once steady state levels have been reached. Norclozapine has minimal therapeutic activity. Test sent to Mayo Medical Laboratories; performed by Mayo New England.