If you’re experiencing depression, there are different diagnostic and treatment options available. This might include lab tests.

There’s more to depression than just psychological and environmental causes. Biological factors and genetics can also play a role.

Your genetics can influence your chances of developing depression. Genes may also impact how medication affects you.

While the research surrounding depression treatments and diagnosis is expanding, discussing your medical history and current symptoms with a healthcare professional is still the standard for diagnosing and treating depression. Still, the biological factors of depression may inspire new options that include routine blood tests.

No, there are currently no lab tests used to predict or determine the best antidepressant for you.

Although the test-to-prescribe science is still in development, obtaining blood work as part of mental health assessments and treatment may still be important.

Lab tests could assist with treatment monitoring, for example.

“If a particular neurotransmitter is low and that neurotransmitter is targeted for treatment, you can repeat the test to ensure that the level has normalized with the treatment,” Dr. Tiffany Mullen, doctor of functional and integrative medicine, explains.

Dr. Anthony Puopolo, chief medical officer of RexMD, points out that blood tests can also “detect dietary sensitivity and illnesses that can affect mood, anxiety, and depression.”

This could help determine other aspects of your treatment that could complement the effects of your antidepressants.

“For instance, for many with gluten sensitivities, consuming wheat can actually cause muddied thoughts and depressive behaviors,” says Puopolo. “Understanding this through blood can allow a person to adjust their diet and vitamin intake to match their needs. This alone is a reason for someone… with depression or anxiety to consider blood testing.”

And while blood work may not help yet in selecting your depression medication, genetic testing could.

Pharmacogenomics is the study of how genes affect drug response.

According to Mullen, the field of pharmacogenomics, “allows one to use genetics to determine if certain medications will be more effective (or conversely, cause side effects) in individuals.”

Different types of tests look at drug compatibility, Dr. Elizabeth Lombardo, a psychologist in Chicago, tells Psych Central.

“A present test called GeneSight predicts the success of your antidepressant medications [by showing] if there are problems between the person’s genetic makeup and the medication that would stop the drugs from working,” Lombardo says.

For example, testing might indicate that you metabolize a drug too quickly. If this is the case, it might leave your system before it has a chance to take effect and you might need a higher or more frequent dose.

Preliminary studies have shown promising results with the use of GeneSight to guide antidepressant selection, but more research is needed.

Currently, there’s no blood test for diagnosing depression.

That may change, though, as researchers learn more about the way this condition might leave biological clues for diagnosticians.

Clinicians typically reach a depression diagnosis by comparing symptoms against the criteria described in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5).

Blood tests are rarely used and when they are, it’s to rule out other health conditions that may explain what you’re experiencing.

Depression does cause physiological changes that could be detected in some blood tests.

Lombardo agrees that blood work may have diagnostic value: “A blood test could show if someone has depression or bipolar disorder. People with depression or bipolar disorder had less of a nerve growth factor than people [without the conditions].”

Nerve growth factor is a type of protein that plays a role in the growth, maintenance, and function of some neurons.

Would assessing nerve growth factor levels also help health professionals choose an antidepressant for you?

Lombardo thinks so. “People in the medical field might be able to use growth factor levels to see how antidepressants work,” Lambardo says.

According to 2021 research, people experiencing certain mood disorders have lower levels of brain-derived neurotrophic factor (BDNF), a type of nerve growth factor.

Major depressive disorder (MDD) and bipolar disorder, for example, are associated with BDNF levels that are significantly low, making a blood test a possible tool in diagnosing and treating those conditions.

BDNF level isn’t the only change in blood samples associated with depression, though.

According to a 2012 research review, ethanolamine phosphate levels also decrease in some people with depression. That would mean that testing for it could help as a diagnostic resource 82% of the time.

Comparing levels of this chemical after you’ve started your antidepressant medication could also help in determining if the drug is helping you.

Additional research in 2016 linked the severity of depression with five plasma metabolites. These are small molecules that are the result or end products of cell metabolism.

In this case, the ones that may indicate severe symptoms of depression are:

Further studies are needed, but evidence suggests that blood tests to check your metabolite profile could become a screening tool for mood disorders.

Together with information about how you feel, monitoring metabolite levels, once you take an antidepressant, could also determine if it’s actually affecting you the way it’s supposed to.

While doctors don’t currently use blood tests to diagnose depression or select an antidepressant medication, they might in the future. Depression can cause changes to several markers that are identifiable in lab tests.

Blood tests can also pinpoint other causes of depression symptoms, like dietary sensitivities. In addition, tests can estimate your compatibility with different types of antidepressant medications.

While your health professional may not be able to use blood tests right now, we’ve compiled a list of options for treating depression and types of antidepressants available now.