According to the World Health Organization, approximately 280 million individuals experience depression on a global scale. Depression is a serious mental health disorder that involves a prolonged period of sadness and a loss of pleasure or interest in activities. It can cause physical symptoms such as lack of energy, pain, and sleeping pattern disruptions. 

Clinically, depression is known as a major depressive disorder (MDD). The symptoms must persist for at least two weeks to be diagnosed with clinical depression. A combination of psychotherapy and antidepressant drugs can help treat this mood disorder. However, one must report their symptoms and obtain a proper diagnosis to access treatment.

Screening is the initial step in getting the necessary care and treatment for depression. Although there’s no single, definitive test available to diagnose depression, the patient’s primary care provider may order blood tests to find out if there are other medical conditions that may cause depressive symptoms like low mood, fatigue, and weight changes.

Before administering blood tests, your physician will ask questions about your overall health status. Note that the blood tests for depression focus on assessing your general health and rule out other health conditions that may contribute to depressive symptoms. 

Complete blood count (CBC)

The complete blood count (CBC) is commonly ordered as a component of a routine medical exam. It comprises a set of tests that assess the number, variety, percentage, concentrations, and quality of blood cells. Ideally, drawing blood is a quick and minimally painful experience. However, some people reported feeling unwell after blood test. 

CBC is used to check and ensure you don’t have iron deficiency, which can cause anaemia. It’s common for people with iron-deficiency anaemia to develop symptoms of depression, such as low energy and poor appetite. Low levels of red blood cell count and haemoglobin can indicate anaemia.

Thyroid Function Panel

Thyroid disease can also affect mood. There are instances where patients with low thyroid function are misdiagnosed with depression. Clinically, a correlation between depressive symptoms and hypothyroidism is also frequently observed. 

Considering the connection between thyroid disorders, it’s standard to screen patients with thyroid disorders for depression. A comprehensive thyroid panel examines the blood for levels of hormones produced by the thyroid gland. An underactive or overactive thyroid can result in mood symptoms.

Fasting blood glucose

Fasting blood glucose measures the amount of sugar in your blood after fasting overnight. It’s a test that can help diagnose prediabetes and diabetes. While the exact connection is unclear, depression and diabetes frequently occur together.

The Centers for Disease Control and Prevention (CDC) reveals that individuals with diabetes are 2 to 3 times more likely to experience depression than those without diabetes. Hence, it only makes sense for physicians to examine the patient’s blood glucose levels before prescribing a medication for depression. 

Vitamin B12 levels

Vitamin B12 is recognised to influence depression. It’s necessary to produce serotonin and dopamine to help the brain work properly. Blood tests for vitamin B12 levels are often unreliable since they can be affected by recent food or supplement intake. 

Even so, checking vitamin B12 levels is worth doing to help screen for depression and rule out other medical conditions. Research shows that lower levels of vitamin B12 in the body are linked to a heightened risk of developing depression. 

Liver function panel

Liver disease can also induce symptoms similar to depression, such as lethargy and fatigue. It’s essential to determine whether these symptoms are caused by depression, liver disease, or a combination of both. Thus, a doctor may also order a liver function panel to assess the health of the patient’s liver.

C-reactive protein level

C-reactive protein (CRP) is a marker in blood linked with systemic inflammation. Checking the levels of CRP is crucial because an increasing amount of research suggests that depression is connected to a chronic, low-grade inflammatory response. 

Specifically, higher blood CRP levels were associated with increased severity and specific patterns of depressive symptoms. They’re also correlated with a poorer response to treatment. Since inflammation is recognized as a pathway to depression and a possible avenue for treatment, it’s sensible for doctors to request a test for CRP. 

Vitamin D test

Deficiency in vitamin D also manifests symptoms similar to those of depression. Studies found that individuals with depression exhibited lower levels of vitamin D than those without the condition. That’s why checking vitamin D levels is one of the components of a physical exam that doctors may require.

One last important reminder

Numerous medical conditions can mimic depression. Some can result in depression as a symptom or side effect. That’s why doctors conduct physical exams, like blood tests, to assess if an underlying physical condition is at play. 

Blood tests are effective at uncovering health conditions and providing valuable information that can aid in determining the right course of treatment for one’s depressive symptoms. Still, a comprehensive mental health care provider evaluation is critical for establishing a clinical diagnosis and corresponding treatment.

Ellen Diamond, a psychology graduate from the University of Hertfordshire, has a keen interest in the fields of mental health, wellness, and lifestyle.