Laboratory (lab)  tests are procedures in which a sample of fluid, tissue or bone is taken from the body and analyzed in a laboratory for signs of diseases. Lab tests are often used to rule out certain disorders associated with symptoms that mimic those of mental illness. In other cases, they may be used to help monitor the effectiveness of a patient’s treatment regimen (e.g., lithium to treat bipolar disorder) or to track the progression of the disease itself.

Although most lab tests are administered by medical professionals in a hospital, clinic or laboratory setting, some tests can be performed by patients in their own homes. Major lab tests that may be used to diagnose and monitor mental health conditions include blood tests and urine tests.

Test results vary from person to person based on a number of factors, including the patient’s gender, age, medical history and general health. Lab test results are only meaningful when compared to established “normal ranges” for that test. These numbers are expressed as a range because the values fluctuate from person to person, and what is considered normal for one person might not be normal for another.

Patients who are scheduled to undergo a lab test should follow any preparatory recommendations suggested by their physician, as some factors are known to potentially influence tests results (e.g., certain foods, vitamins). Patients should report engaging in any activities that deviate from their pre-testing regimen, as failure to closely follow preparatory recommendations can lead to inaccurate test results and a faulty diagnosis.