Diagnosis Of Depression: Can Blood Tests Help?

Depression is one of the most common mental illnesses in the world which makes a person feel sad or unable to enjoy anything for days or weeks at a stretch. It can negatively affect the way you feel, the way you think and the way you act. Depression can affect people of any age, including children. It can strike at any time, but on an average, it majorly affects teens and those in the mid-20s[1]. Women are more likely to experience depression than men. At a global level, 322 million people are estimated to suffer from depression, equivalent to 4.4% of the world’s population [2]. By the year 2020, depression is projected to reach the 2nd place of the ranking of DALYs (Disability-Adjusted Life Years) calculated for all ages, both sexes. DALYs is the measure of the number of years lost due to ill-health, disability or early death[1].

Symptoms of depression

-Feeling sad or unhappy without any reason

-Loss of interest or pleasure. For example, you do not enjoy the things you used to enjoy earlier

-Feeling of guilt or worthlessness

-Disturbed sleep such as insomnia or excessive sleeping

-Changes in appetite: Some people experience weight loss whereas some people experience increased food cravings and weight gain

-Low energy and poor concentration

-Irritability, frustration or angry outbursts

-Reduced sex drive


-Slowed thinking, speaking or body movements

-Fatigue, tiredness, and loss of energy, even small tasks may need a lot of effort

-Fixating on past failures or blaming yourself when things are not going right

-Trouble in thinking, in making decisions and in remembering things

-Frequent thoughts of death, dying or suicide

-Crying for no reason

-Unexplained physical problems, such as back pain or headaches

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Can Blood Tests Help Diagnose Depression?

It is essential to understand that the underlying cause of depression varies from person to person. This is the reason why you must consult a doctor or a psychiatrist if any of the symptoms of depression last for more than 2 weeks. Most of the doctors use detailed interviews which may be based on certain questionnaires. The diagnosis is made based on the signs the doctor observes during your office visit, your medical history, and your family’s medical history.

As of today, there is no sure shot laboratory test, blood test, or X-ray that can definitively diagnose a mental disorder. But there are a few blood tests that can aid in the diagnosis of depression. Here are 6 blood tests that can help diagnosis for depression

1) Thyroid Function Test: The thyroid function test measures the blood levels of the hormones produced by the thyroid gland. These are Thyroid Stimulating Hormone (TSH), Thyroxine (T4) – Total and TriIodothyronine (T3) – Total. When the thyroid gland is either overactive or underactive, it can contribute to mood disorders. Hypothyroidism is a condition that occurs when your thyroid gland does not produce enough thyroid hormones. The symptoms include slowing of physical and mental functions, fatigue, lethargy, and sleep disturbances. Hyperthyroidism, also called overactive thyroid, is when the thyroid gland produces more hormone than your body requires. The symptoms include weight loss, fatigue, weakness, and irritability. The symptoms of abnormal thyroid activity are similar to those of depression. It may give a clue to the doctor that the signs and symptoms of depression can be due to abnormal thyroid function.

2) Complete Blood Count (CBC): CBC is a group of tests that provides information about blood cells. It is routinely performed to provide an overview of a patient’s general health status. It may aid in diagnosis for conditions like anemia and infection, both of which may cause symptoms that are similar to depression, like fatigue, weight loss, and lethargy.

3) Kidney Function Test (KFT): KFT includes a group of blood tests to determine how well the kidneys are working. This test is important because kidney disease can lead to symptoms similar to depression.  It may give a clue to the doctor that the signs and symptoms of depression can be due to abnormal kidney dysfunction.

Checking the function of the kidney is also essential because any problem in kidney function can influence the metabolism of medications that are used for treating depression.

4) Liver Function Test (LFT): LFT includes a group of blood tests performed to check the functions of the liver. This test measures the level of various liver enzymes, proteins, and bilirubin in the blood. Liver disease can cause symptoms similar to depression, such as fatigue, lethargy, decreased mental alertness, confusion, weakness, anorexia, and weight loss.

Checking how well the liver is functioning is important as any impairment in liver function can influence the metabolism of medications that might be used for treating depression[3]. Also, poor liver function may be caused by alcohol abuse, which may be an indicator of depression[4].

5) Fasting Blood Glucose: The fasting glucose test provides a view of the amount of glucose in the blood after fasting or not eating anything for at least 8 hours. The exact link between depression and diabetes is unclear. Most people with diabetes do not have depression but studies[5,6] show that people with diabetes are at a higher risk of depression than people without diabetes. The increased threat might be because of the stress and tension of managing diabetes on daily basis. This test may also be necessary before prescribing medications for depression.

6) Folic Acid and Vitamin B12 Levels: Low levels of either folic acid or vitamin B12 are associated with pernicious anemia. Pernicious anemia may further cause symptoms of depression like lethargy, mood disorders, confusion, and insomnia.

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Take home message

There are many ways of fighting and managing depression. You do not need to worry if you have depression or if you know someone who has depression. Depression can be treated with proper medical guidance and this is why it is important to visit a doctor and speak about how you feel. Go for a health check-up and take up the required blood tests as advised by your doctor to know if something is wrong. Talk to your doctor about how you feel and what can be done to deal with the condition. This can always aid in improving the possible outcome of the treatment and therapy for people with depression.

In addition to antidepressants and counseling, there are few tips that can help you to fight depression such as:

A healthy diet can contribute to elevate your mood more than you think. It keeps you energized throughout the day.

Sleeping well and having a good quality sleep also helps. Do not be irregular with your sleep timings.

Regular exercise improves your health as well as your mood. It creates a positive feeling which helps you to be active not only physically but also mentally.

Avoid alcohol if you are depressed. Consuming alcohol will just add up to your depression.

Remember the diagnosis of depression plays a crucial role in the treatment of the condition. Know the symptoms, consult a doctor and get it treated.

(The article is reviewed by Dr. Lalit Kanodia, General Physician)

Recommended Reads:

Here Is What You Need To Know When Getting A Blood Test Done

7 Myths About Depression That Are Simply Not True!


1) Debjit Bhowmik. Depression – Symptoms, Causes, Medications and
Therapies. The Pharma Innovation. Vol. 1 No. 3 2012.

2) Depression and Other Common Mental Disorders: Global Health Estimates. Geneva: World Health Organization; 2017. Licence: CC BY-NC-SA 3.0 IGO.

3) Annals of Pharmacology; Antidepressant-Induced Liver Injury; Kevin DeSanty, Pharm.D., Ph.D.; July 2007

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