Tests
1st tests to order
clinical diagnosis
Test
Diagnosis is based on diagnostic criteria (DSM-5-TR or ICD-11) with tests performed to rule out other etiologies as indicated.
Result
fulfills diagnostic criteria (DSM-5-TR or ICD-11)
Tests to consider
MRI/CT head
Test
Indicated on the basis of neurologic examination or history.[65] MRI is preferred to CT.[65] Factors that suggest a possible need for imaging include focal neurologic signs, new onset of seizures, later age at symptom onset, symptoms suggestive of intracranial pathology (e.g., chronic or severe headaches, nausea, vomiting), and symptoms suggestive of autoimmune encephalitis (e.g., rapid progression of working memory deficits over less than 3 months; decreased or altered level of consciousness, lethargy, or personality change).[65]
Result
normal in schizophrenia; not routinely requested unless there are neurologic abnormalities or late onset
serum HIV enzyme-linked immunosorbent assay
serum rapid plasma reagin (RPR) test
Test
Indicated in any patient at risk of STIs. Syphilis infection can cause psychiatric symptoms and should be excluded.
Result
normal in schizophrenia; positive in syphilis infection
CBC including absolute neutrophil count (ANC)
Test
Decreased hemoglobin, decreased hematocrit; increased or decreased mean corpuscular volume are found in anemia. Fatigue and depression are associated with anemia and can mimic negative symptoms of schizophrenia.
Volume abnormalities in red blood cells can also suggest vitamin deficiencies or increased alcohol intake, which could be associated with psychosis.
Result
normal in schizophrenia; decreased Hb in anemia
drug toxicology screen
Test
Drug intoxication can lead to psychotic-like symptoms or to exacerbation of psychotic illness. Drug toxicology screen is recommended if clinically indicated in any patient presenting with a psychotic episode.[65]
Result
normal in schizophrenia
BUN and electrolytes
Test
Recommended as initial or baseline assessment.[65]
Result
normal in schizophrenia
liver function tests
Test
Recommended as initial or baseline assessment.[65]
Result
normal in schizophrenia; elevated with liver disease
thyroid-stimulating hormone
Test
Recommended as initial or baseline assessment.[65] Fatigue and depression are associated with thyroid dysfunction and can mimic negative symptoms of schizophrenia.
Result
normal in schizophrenia; rules out thyroid dysfunction
pregnancy test
Test
Recommended for women of childbearing age.
Result
positive in pregnancy
genetic testing
Test
May be indicated on the basis of physical exam or history, including developmental history.[65] Factors that may suggest a possible need for chromosomal testing (e.g., to identify abnormalities such as 22q11.2 deletion syndrome) include mild dysmorphic features, hypernasal speech, developmental delays, intellectual impairments, learning difficulties, and congenital heart defects.[65]
Result
22q11.2 deletion syndrome
Use of this content is subject to our disclaimer