# A client with treatment-resistant schizophrenia is starting clozapine. Which baseline laboratory test must be documented before each dispensing of the medication?

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> language: en  
> subject: Medical Emergencies  
> category: PA

## Question

A client with treatment-resistant schizophrenia is starting clozapine. Which baseline laboratory test must be documented before each dispensing of the medication?

## Option

1. Hemoglobin A1c
2. Absolute neutrophil count (ANC) **✔ Correct answer**
3. Liver enzymes
4. Serum sodium

**Correct answer: 2**

## Explanation

Correct (2): Clozapine carries a boxed warning for severe agranulocytosis (~1% incidence). The Clozapine REMS program requires documented ANC ≥1500/mm³ before each dispense — weekly for the first 6 months, biweekly months 7-12, then monthly thereafter. The drug must be held if ANC

## In-depth explanation

Memory Tip "Clozapine = ANC clock" — weekly × 6 months, biweekly × 6 months, then monthly. Caution Clients must report fever, sore throat, mouth ulcers, or flu-like symptoms IMMEDIATELY — infection during clozapine-induced neutropenia can be fatal. Clinical Practice Guide Pharmacies cannot dispense without a current ANC documented in REMS; missed labs interrupt therapy.

## Clinical scenario

Scenario A 28-year-old male with treatment-resistant schizophrenia has failed adequate trials of olanzapine and risperidone. The provider prescribes clozapine 12.5 mg PO BID with a planned titration. REMS program enrollment is complete and the pharmacy is awaiting clearance to dispense.

## Key concepts

- **Clozapine REMS** — A national restricted-distribution program requiring documented ANC monitoring at specified intervals; pharmacies cannot dispense clozapine without a current result.
- **Agranulocytosis** — Severe neutropenia (ANC
- **Treatment-resistant schizophrenia** — Schizophrenia that has failed adequate trials of at least two other antipsychotics; clozapine is uniquely effective and is the recommended next-line agent.

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