What is the role of lab testing in the diagnosis and management of schizophrenia?

Updated: Mar 16, 2018
  • Author: Frances R Frankenburg, MD; Chief Editor: Glen L Xiong, MD  more...
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Schizophrenia is not associated with any characteristic laboratory results. The following should be performed on all patients, both at the beginning of the illness and periodically afterward, to rule out other or concomitant illnesses:

  • Complete blood cell (CBC) count

  • Liver, thyroid, and renal function tests

  • Electrolyte, glucose, vitamin B-12, serum methylmalonic acid, folate, and calcium levels

  • Pregnancy testing (if the patient is a woman of childbearing age)

  • Urine testing for drugs of abuse, such as alcohol, cocaine, opioids, cannabis

  • Urine for culture and sensitivity (to look for urinary tract infection)

  • Brain imaging to rule out subdural hematomas, vasculitis, cerebral abscesses, and tumors

Other tests to consider, if the history provides any reason for suspicion (see Differentials), are as follows:

  • Urine and serum copper and ceruloplasmin - If a strong suspicion of Wilson disease exists, consider a liver biopsy (or multiple biopsies)

  • Twenty-four-hour urine collections for porphyrins, copper, or heavy metals

  • Dexamethasone suppression test for hypercortisolism; corticotropin stimulation test for hypocortisolism, morning cortisol

  • Rapid plasma reagin (RPR) - If a strong suspicion of neurosyphilis exists, specific treponemal tests may be helpful

  • HIV antibodies

  • Lyme antibodies

  • Antinuclear antibody (ANA) for systemic lupus erythematosus

  • Chest radiography to rule out pulmonary illness or occult malignancy

  • Electroencephalography (EEG)

Some experts suggest that a lumbar puncture be performed to examine cerebrospinal fluid, especially to rule out inflammatory and infectious CNS disorders. 

Neuropsychological testing may be considered; determination of the patient’s cognitive weaknesses and strengths can be helpful in treatment planning. Common findings in patients with schizophrenia are as follows:

  • Poor executive functioning (ie, poor planning, organizing, or initiation of activities)

  • Impaired memory

  • Difficulty in abstraction and recognizing social cues

  • Easy distractibility

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