Laboratory Tests For Depression

Depression is a complex disease that involves imbalance of various chemicals and their interactions. As such there is no single chemical held responsible for causing depression.

Moreover, there is no exact cause known for depression and thus, there is no exact diagnostic laboratory test for identifying depression.

A psychiatrist recommends the diagnostic tests on the basis of various factors.

  • Age of the patient
  • Physical symptoms of the patient
  • Medical history of the patient
  • Fewer Tests for individuals who have less symptoms and are younger than 40
  • More tests for individuals who have many symptoms and are older than 50

Even though the diagnostic tests do not help much with root cause of depression, they can help in evaluating the reasons of depression.

The various laboratory tests help in identifying the presence of any medical problems that may result in depression. In fact, diagnostic tests make up an important part of overall evaluation of depression.

Common Laboratory tests for evaluating Depression

  • Blood tests for TSH and thyroxin levels for excluding hypothyroidism
  • Basic electrolytes and serum calcium for ruling out metabolic disturbances
  • Full blood count including ESR for ruling out a systemic infection
  • Adverse affective reactions for alcohol misuse
  • Evaluation of Testosterone levels for diagnosing hypogonadism
  • Subjective cognitive complaints in older depressed people

All these tests are not meant for depression itself; however they assist in ruling out various medical problems that underlies depression. Thus, evaluation of the results of these tests helps in determining the proper treatment for you.

Blood Tests

A blood test provides valuable information regarding the functioning of various glands of the body.

Thyroid Gland: The functioning of the thyroid gland can be checked by measuring the levels of certain hormones in the blood.

Low levels of thyroid hormone (hypothyroidism) present the symptoms similar to depression. Thus,

if patient is suffering from hypothyroidism, the symptoms of depression can be treated by thyroid disorder.

Fatigue or Weight Loss: In case patient complains of fatigue or weight loss, psychiatrists may recommend complete blood count and chemistry profile.

Anaemia: Patients suffering from anaemia have low count of red blood cells (RBC). It can be evident from the results of complete blood count that measures the number of RBC and WBC in blood.

Infection in Immune System: The presence of very low or high numbers of WBC in blood count may indicate the presence of infection or problem with immune system.

Kidney and Liver Disorders: A chemical profile of the blood helps in evaluating the function of your kidney and liver. It identifies the irregularities in the concentration of various substances (sugar and cholesterol) in body.


A chest X-ray is recommended by a psychiatrist if he/she suspects a specific problem related to lung or heart disease. Moreover, X-rays or scans also help in evaluating different kinds of cancer.

Other Imaging Techniques

Computed tomography (CT) and Magnetic Resonance Imaging (MRI) are used for evaluating neurological illnesses. Your psychiatrist may suspect a neurological illness by evaluating the symptoms of physical examination.

In severe cases, an electroencephalogram is performed for diagnosing a seizure disorder and offers useful information about functioning of the brain.