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Test Code CLZ Clozapine, Serum

Useful For

Monitoring patient compliance of clozapine treatment

 

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


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

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

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:  

1. Collect specimen immediately before next scheduled dose.

2. Within 2 hours of collection, centrifuge and aliquot serum into a plastic vial.

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

Clozapine

Therapeutic range: 350-600 ng/mL

 

Norclozapine

Therapeutic range: Not well established

 

Clozapine + Norclozapine

Therapeutic range: Not well established

Interpretation

The effectiveness of clozapine treatment should be based on clinical response and treatment should be discontinued in patients failing to show an acceptable clinical response.

Clinical Reference

1. Volpicelli SA, Centorrino F, Puopolo PR, et a,: Determination of clozapine, norclozapine, and clozapine-N-oxide in serum by liquid chromatography. ClinChem. 1993;39(8):1656-1659

2. Chung MC, Lin SK, Chang WH, Jann MW. Determination of clozapine and desmethylclozapine in human plasma by high-performance liquid chromatography with ultraviolet detection. J Chromatogr. 1993;613(1):168-173. doi:10.1016/0378-4347(93)80212-m

3. Perry PJ, Miller DD, Arndt SV, Cadoret RJ. Clozapine and norclozapine plasma concentrations and clinical response of treatment-refractory schizophrenia patients. Am J Psychiatry. 1991;148(2):231-235. doi:10.1176/ajp.148.2.231

4. Physicians' Desk Reference (PDR). 61st ed. Thomson PDR; 2007

5. Fitton A, Heel RC. Clozapine. A review of its pharmacological properties, and therapeutic use in schizophrenia. Drugs. 1990;40(5);722-747. doi:10.2165/00003495-199040050-00007

6. Clozaril. Package insert: Novartis Pharmaceuticals; 05/2005

7. Mitchell PB. Therapeutic drug monitoring of psychotropic medications. Br J Clin Pharmacol. 2001;52(Suppl 1):45S-54S. doi:10.1046/j.1365-2125.2001.0520s1045.x

8. Hiemke C, Bergemann N, Clement HW, et al. Consensus Guidelines for Therapeutic Drug Monitoring in Neuropsychopharmacology: Update 2017. Pharmacopsychiatry. 2018;51(1-02):9-62. doi:10.1055/s-0043-116492

9. Milone MC, Shaw LM: Therapeutic drugs and their management. In: Rifai N, Chiu RWK, Young I, Burnham CAD, Wittwer CT, eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier; 2023:420-453

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. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

80159

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

Forms

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