Blood Tests for Depression and Anxiety: What to Check, and Where Medication Fits

Alternative to Meds Editorial Team
Medically Reviewed by Dr John Motl MD

Can a blood test detect depression?

No. There is no blood test that diagnoses depression, anxiety, or other mental health conditions. Diagnosis is based on your symptoms and history.

Blood tests can also find physical problems that cause or worsen the same symptoms: low mood, anxiety, fatigue, poor sleep, and trouble concentrating. An underactive thyroid, a vitamin deficiency, or iron deficiency can look a lot like depression.^1-4 Finding and treating these doesn’t replace mental health care, but it can make a real difference to how you feel.

Why physical health matters for mental health

The brain depends on the rest of the body. Hormones, nutrients, blood sugar, sleep, and inflammation all affect how it works. When one of them is off, symptoms can show up as mood, energy, or thinking problems.

That’s why it makes sense to check physical health:

• Before deciding a medication is needed, so a treatable physical cause isn’t missed.
• When treatment isn’t working, or symptoms change without a clear reason.
• When reviewing long-term medication, as part of deprescribing.

Lab tests worth discussing with your doctor

Your doctor will decide which tests make sense for you. These are some of the most commonly discussed:

• Thyroid function (TSH and related tests). Thyroid problems are linked with depression, anxiety, fatigue, and weight changes.¹
• Vitamin D. Low levels are associated with depression.²
• Vitamin B12 and folate. Low levels can affect mood, energy, and memory, and may affect how well depression responds to treatment.³
• Iron and a complete blood count. Iron deficiency and anemia cause fatigue and are associated with higher rates of psychiatric conditions.⁴
• Blood sugar. Swings in blood sugar can cause irritability, anxiety, and low energy.
• Metabolic panel. Liver and kidney function, electrolytes, and how your body is handling any medications.
• Hormones, such as cortisol and sex hormones, when symptoms suggest a hormonal component.

A normal result is useful too. It helps rule things out and points care in the right direction.

Nutrition and supplements: what they can and can’t do

What they can do. When labs show a real deficiency, correcting it is good medicine. Diet matters too: in one trial, adults with depression who improved their diet with a dietitian’s support improved more than those who received social support alone.⁵ Some nutrients also have research support as an addition to standard treatment for certain conditions.⁶

What they can’t do. Supplements are not a substitute for needed treatment, and not every psychiatric symptom comes from a deficiency. A large review of supplement trials found that many popular supplements had little evidence of benefit for mental health conditions.⁶ More isn’t better, either: some supplements interact with medications or cause problems at high doses.

The most useful approach is targeted: test, find what is actually low or out of balance, correct it, and keep the rest of your care in place.

Where psychiatric medication fits

Psychiatric medication can be helpful and sometimes lifesaving, especially with severe symptoms, in a crisis, or when other approaches haven’t helped. Checking physical health first is not about avoiding medication at all costs. It’s about making sure the whole picture is understood, so that if medication is used, it’s for the right reasons, alongside everything else that supports recovery.

For many people, the best care combines several things: treating any physical causes, good nutrition and sleep, counseling, and medication when it’s needed.

If you already take psychiatric medication

Lab work is useful here too. Some psychiatric medications affect weight, blood sugar, cholesterol, hormones, or nutrient levels, and checking them can catch problems early.

If you have taken a medication for years and wonder whether you still need it, lab work is a natural part of that conversation. Our guide to deprescribing explains how a medication review works. If you take an antidepressant, see our complete guide to coming off antidepressants.

Don’t stop or change a psychiatric medication because of a lab result. Talk with your prescriber first.

How ATMC uses lab testing

At Alternative to Meds Center, every residential stay starts with comprehensive lab work, including:

• Complete metabolic panel, including liver and kidney function
• Complete blood count with differential
• Thyroid, blood sugar, iron, and other metabolic markers
• Cortisol and comprehensive sex hormones
• Amino acids and trace minerals
• Additional tests as requested by our medical team

Results guide each client’s plan: nutrition and targeted supplementation through our orthomolecular and naturopathic team, and, for clients who are reducing medication, an individualized taper planned and monitored by our medical and nursing staff. Clients live at our residence in Sedona, Arizona, for about 60 days on average.

Learn more about lab testing at ATMC and our inpatient medication tapering.

Get help

If you want to understand what’s behind your symptoms, or you’re questioning a medication you’ve taken for years, our admissions team can talk through your situation.

Lab tests and mental health FAQs

Sources:

1. Hage MP, Azar ST. The Link between Thyroid Function and Depression. J Thyroid Res. 2012;2012:590648. PMID: 22220285. [cited 2026 Oct 15]

2. Anglin RE, Samaan Z, Walter SD, McDonald SD. Vitamin D deficiency and depression in adults: systematic review and meta-analysis. Br J Psychiatry. 2013 Feb;202:100-107. PMID: 23377209. [cited 2026 Oct 15]

3. Coppen A, Bolander-Gouaille C. Treatment of depression: time to consider folic acid and vitamin B12. J Psychopharmacol. 2005 Jan;19(1):59-65. PMID: 15671130. [cited 2026 Oct 15]

4. Chen MH, Su TP, Chen YS, et al. Association between psychiatric disorders and iron deficiency anemia among children and adolescents: a nationwide population-based study. BMC Psychiatry. 2013 Jun 4;13:161. PMID: 23735056. [cited 2026 Oct 15]

5. Jacka FN, O’Neil A, Opie R, et al. A randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial). BMC Med. 2017 Jan 30;15(1):23. PMID: 28137247. [cited 2026 Oct 15]

6. Firth J, Teasdale SB, Allott K, et al. The efficacy and safety of nutrient supplements in the treatment of mental disorders: a meta-review of meta-analyses of randomized controlled trials. World Psychiatry. 2019 Oct;18(3):308-324. PMID: 31496103. [cited 2026 Oct 15]

Originally Published October 15, 2026 by Alternative to Meds Editorial Team

This content has been reviewed and approved by a licensed physician.

Dr. John Motl, M.D.

Dr. Motl is currently certified by the American Board of Psychiatry and Neurology in Psychiatry, and Board eligible in Neurology and licensed in the state of Arizona.  He holds a Bachelor of Science degree with a major in biology and minors in chemistry and philosophy. He graduated from Creighton University School of Medicine with a Doctor of Medicine.  Dr. Motl has studied Medical Acupuncture at the Colorado School of Traditional Chinese Medicine and at U.C.L.A.

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Diane Ridaeus

Diane is an avid supporter and researcher of natural mental health strategies. Diane received her medical writing and science communication certification through Stanford University and has published over 3 million words on the topics of holistic health, addiction, recovery, and alternative medicine. She has proudly worked with the Alternative to Meds Center since its inception and is grateful for the opportunity to help the founding members develop this world-class center that has helped so many thousands regain natural mental health.