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Test ID CLZ Clozapine, Serum

Useful For

Monitoring patient compliance


An aid to achieving desired serum levels

Method Name

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

Reporting Name

Clozapine, S

Specimen Type

Serum Red

Ordering Guidance


Specimen Required

Collection Container/Tube: Red top (serum gel/SST are not acceptable)

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions: Centrifuge and aliquot serum into plastic vial within 2 hours of collection.

Additional Information: Therapeutic range (trough level) applies to specimens collected immediately prior to next dose.

Specimen Minimum Volume

0.6 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Red Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  7 days

Reference Values


Therapeutic range: 350-600 ng/mL



Therapeutic range: Not well established



Therapeutic range: Not well established

Day(s) Performed

Monday through Friday

Report Available

3 to 5 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
CLZ Clozapine, S 65632-2


Result ID Test Result Name Result LOINC Value
33840 Clozapine 6896-5
33841 Norclozapine 10992-6
33842 Clozapine+Norclozapine Total 12375-2


If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.