What tests should be included in a blood workup for schizophrenia?

Blood Workup for Schizophrenia

A comprehensive blood workup for schizophrenia should include complete blood count, comprehensive metabolic panel, thyroid function tests, toxicology screen, and other tests based on clinical presentation to rule out medical causes of psychotic symptoms.

Basic Laboratory Tests

The American Academy of Child and Adolescent Psychiatry recommends the following laboratory tests as part of the basic medical evaluation for patients with suspected schizophrenia:

• Complete blood count (CBC) to assess for underlying infections or hematologic abnormalities 1
• Comprehensive metabolic panel including serum chemistry studies, calcium, magnesium, and liver function tests 1
• Thyroid function tests to rule out thyroid disorders that can present with psychiatric symptoms 1
• Toxicology screen to identify substance-induced psychosis 1
• Urinalysis to rule out infections or other abnormalities 1

Additional Tests Based on Clinical Presentation

Depending on clinical findings and risk factors, these additional tests may be warranted:

• Human immunodeficiency virus (HIV) testing if risk factors are present 1
• Chromosomal analysis if features suggest a developmental syndrome 1
• Erythrocyte sedimentation rate (ESR) to assess for inflammatory conditions 1
• Vitamin B12 and folate levels to rule out deficiencies that can affect cognition 1
• Rapid plasma reagin (RPR) or fluorescent treponemal antibody absorption (FTA-ABS) to screen for syphilis 1
• Lyme antibody testing if clinically indicated 1

Metabolic Monitoring

For patients already diagnosed with schizophrenia and taking antipsychotic medications, metabolic monitoring is essential due to the high risk of metabolic syndrome:

• Fasting blood glucose or glycosylated hemoglobin (HbA1c) 2
• Lipid profile (total cholesterol, LDL, HDL, triglycerides) 2
• Liver function tests to monitor for medication effects 2
• Prolactin levels, particularly for patients on antipsychotics known to elevate prolactin 2

Specialized Testing

In cases with atypical presentation or when neurological symptoms are present:

• Electroencephalogram (EEG) if seizure disorder is suspected 1
• Cerebrospinal fluid (CSF) analysis if CNS infection or inflammatory process is suspected 1
• Autoimmune panels if autoimmune encephalitis is suspected 1

Emerging Biomarkers

While not yet standard clinical practice, research suggests potential value in:

• Inflammatory markers such as cytokines and C-reactive protein 3
• Metabolomic panels that may help identify underlying metabolic disturbances 4
• Neuroendocrine markers that may reflect stress-related pathophysiology 3

Clinical Considerations and Pitfalls

• Laboratory testing is used to rule out medical causes of psychotic symptoms, not to diagnose schizophrenia itself 1
• Substance-induced psychosis is common, especially in adolescents, with rates of comorbid substance abuse as high as 50% in some studies 1
• If psychotic symptoms persist for longer than one week despite documented detoxification, consider primary psychotic disorder rather than substance-induced psychosis 1
• Regular metabolic monitoring is critical for patients on antipsychotic medications, as metabolic syndrome prevalence is 5 times higher in schizophrenia patients compared to matched controls 5
• First-episode schizophrenia patients may already show metabolic abnormalities even before long-term antipsychotic treatment 5

Frequency of Monitoring

For patients on antipsychotic medications:

• Baseline testing before starting medication 2
• Follow-up testing at 3 months, 6 months, and then annually 2
• More frequent monitoring may be needed for patients with abnormal results or high-risk profiles 2

Remember that laboratory testing is just one component of a comprehensive assessment for schizophrenia, which should also include detailed psychiatric evaluation, physical examination, and consideration of neuroimaging when clinically indicated 1.