What laboratory tests should be obtained prior to starting antipsychotic medication?

Baseline Laboratory Testing Before Starting Antipsychotics

Before initiating any antipsychotic medication, obtain the following comprehensive panel: BMI, waist circumference, blood pressure, HbA1c, fasting glucose, lipid profile, prolactin, liver function tests (ALT/AST), urea and electrolytes, complete blood count, and electrocardiogram. 1

Core Metabolic and Cardiovascular Assessment

Required Laboratory Tests

• Fasting glucose and HbA1c to screen for diabetes or prediabetes, as antipsychotics carry significant metabolic risk 1, 2, 3
• Lipid panel (fasting) including total cholesterol, LDL, HDL, and triglycerides to establish cardiovascular risk baseline 1, 2, 3
• Liver function tests (ALT and AST) since atypical antipsychotics may cause transient transaminase elevations, particularly in the first 3 weeks 4, 2, 3
• Renal function (urea and electrolytes) to assess kidney function, especially important if metformin will be considered for metabolic management 1
• Complete blood count to screen for hematological abnormalities such as leukocytopenia and thrombocytopenia 1, 2, 3

Physical Measurements

• BMI and waist circumference to establish metabolic baseline, as weight gain is a major concern with most antipsychotics 1, 2, 3
• Blood pressure to detect pre-existing hypertension and monitor for orthostatic hypotension risk 1, 2, 3

Cardiac Assessment

• Electrocardiogram (ECG) to evaluate QTc interval, as many antipsychotics can cause QT prolongation, particularly ziprasidone, haloperidol, and quetiapine 1, 2, 3

Endocrine Testing

• Prolactin level to establish baseline, as many antipsychotics (especially haloperidol and risperidone) cause significant hyperprolactinemia 1, 2
• Pregnancy test in women of childbearing age before initiating treatment 2, 3

Medication-Specific Additional Requirements

For Clozapine Specifically

Clozapine requires mandatory white blood cell monitoring due to 1% risk of fatal agranulocytosis. 4

• Baseline WBC count must be at least 3,500/mm³ with no evidence of myeloproliferative disorder or history of agranulocytosis 4
• Absolute neutrophil count (ANC) must be documented at baseline 4
• Document any preexisting abnormal movements to avoid later mislabeling them as medication-induced tardive dyskinesia 4

For Quetiapine Specifically

• Baseline ophthalmologic examination is recommended by the FDA, as quetiapine was associated with cataract development in animal studies 3
• Follow-up eye examinations should be performed every 6 months while on therapy 3

Critical Clinical Context

Medical History Requirements

A thorough medical history must document: 1

• Current medications including prescribed, over-the-counter, complementary/alternative treatments, or illicit substances
• Medication allergies
• Personal history of structural cardiac abnormalities (especially before stimulants)
• Family history of malignant arrhythmias or sudden cardiac death (especially before atypical antipsychotics)
• Personal or family history of diabetes, dyslipidemia, or cardiovascular disease

Psychiatric Documentation

• Comprehensive psychiatric evaluation with adequate documentation of targeted psychotic symptoms is necessary before initiating antipsychotics 4
• Document baseline movement disorders to distinguish pre-existing conditions from treatment-emergent extrapyramidal symptoms 4

Common Pitfalls to Avoid

Pragmatic Considerations for Glucose Testing

If a fasting glucose sample cannot be obtained, a random glucose sample can be used as an initial screening measure; however, if this is not in the healthy range, a fasting measure should be prioritized. 1

High-Risk Populations Requiring Enhanced Baseline Assessment

• Patients with pre-existing diabetes or prediabetes require documentation of current glycemic control 2, 3
• Elderly patients warrant closer attention to baseline cardiovascular parameters and cognitive status 5
• Adolescents should have particularly careful metabolic baseline documentation, as they experience significantly greater weight gain (mean 11.24 kg vs 4.81 kg in adults) and more pronounced lipid abnormalities than adults 2

Renal Function Assessment Before Metformin

If metformin will be considered as adjunctive treatment for metabolic management (particularly with olanzapine or clozapine), renal function must be assessed at baseline, as metformin should be avoided in renal failure. 1