10 Things Your Psychiatrist Should Be Testing (But Probably Isn’t)

You’ve been doing everything right — showing up to appointments, trying different medications, even adjusting your sleep and exercise. But something still feels off, and nobody can tell you why.

If your mental health care has felt like a guessing game, you’re not alone. Most psychiatric visits last 15 minutes, focus on symptoms, and end with a prescription adjustment. What’s missing? Lab work. Specifically, the kind of lab work that reveals what’s actually happening in your body — not just your brain.

Here’s the truth: what your psychiatrist should test for goes far beyond a basic metabolic panel or a quick thyroid screen. Depression, anxiety, brain fog, and fatigue can all have biological root causes that a standard psychiatric evaluation never uncovers. When those root causes go untested, you end up chasing symptoms instead of solving problems.

This list covers 10 lab tests that a functional medicine approach to psychiatry would include — and explains why each one matters for your mental health. Whether you bring this list to your current provider or decide it’s time for a more thorough approach, you deserve answers that go deeper than “let’s try a different dose.”

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1. Complete Thyroid Panel (Not Just TSH)

Here’s a scenario that plays out constantly: you tell your doctor you’re exhausted, gaining weight, and feeling depressed. They check your TSH (thyroid-stimulating hormone), it comes back at 3.5 mIU/L, and they say, “Your thyroid is fine.” But is it?

A TSH alone is like checking the oil light on your dashboard without ever opening the hood. A complete thyroid panel includes TSH, Free T4, Free T3, Reverse T3, and thyroid antibodies (TPO and thyroglobulin). Each of these tells a different part of the story. You could have a “normal” TSH but elevated antibodies — meaning your immune system is attacking your thyroid years before it shows up on a standard screen. That’s Hashimoto’s thyroiditis, and it’s one of the most underdiagnosed contributors to depression, anxiety, and cognitive fog.

At Willow & Stone, we run a full thyroid panel as part of our baseline evaluation because we’ve seen too many patients suffer needlessly when subclinical thyroid dysfunction gets dismissed. Optimal Free T3, for example, is typically in the upper third of the reference range — not just “within normal limits.” That distinction matters when you’re trying to figure out why you can’t get off the couch.

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2. Vitamin D, B12, and Folate Levels

These three nutrients are foundational to how your brain produces and uses neurotransmitters — the chemical messengers behind your mood, motivation, and focus. And deficiencies are staggeringly common: roughly 42% of American adults are vitamin D deficient, and B12 deficiency is especially prevalent in people who take metformin, eat a plant-based diet, or are over 50.

Low vitamin D (below 30 ng/mL, though many functional providers aim for 50–80 ng/mL) has been linked in research to higher rates of depression, seasonal mood changes, and even poor medication response. B12 and folate are critical for methylation — a biochemical process your body uses to make serotonin, dopamine, and norepinephrine. When methylation is sluggish, no amount of an SSRI can fully compensate.

The frustrating part? Low vitamin D and B12 can mimic or worsen psychiatric symptoms so closely that the deficiency gets misdiagnosed as treatment-resistant depression. A simple blood draw can clarify the picture. We check these levels on nearly every patient and often find they’re a missing piece of the puzzle.

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3. Iron and Ferritin

Most providers check a CBC (complete blood count) and call it a day. But your hemoglobin can look perfectly normal while your ferritin — your body’s iron storage protein — is sitting in the basement. Ferritin levels below 30 ng/mL (and some research suggests below 50 ng/mL) can cause fatigue, restless legs, difficulty concentrating, and mood instability, even without anemia.

Think about it this way: iron is essential for making dopamine, the neurotransmitter behind motivation and pleasure. If you’ve been told your depression “isn’t responding” to medication, but nobody has checked your ferritin, there’s a massive blind spot in your care.

This comes up often with women of reproductive age, athletes, and anyone with heavy periods or a history of restrictive eating. At Willow & Stone, ferritin is part of our advanced psychiatric lab testing protocol because a $15 blood test shouldn’t be the thing standing between you and feeling like yourself again.

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4. hs-CRP (Inflammation Marker)

Inflammation isn’t just about swollen joints or a sore throat. A growing body of research suggests that chronic, low-grade inflammation in the body is closely tied to depression, particularly the kind that shows up as fatigue, low motivation, social withdrawal, and that heavy “I can’t do anything” feeling — sometimes called sickness behavior.

High-sensitivity C-reactive protein (hs-CRP) is a simple blood test that measures systemic inflammation. An optimal level is below 1.0 mg/L. Levels above 3.0 mg/L indicate significant inflammation and have been associated in multiple studies with poorer response to standard antidepressants. Some researchers are even exploring whether anti-inflammatory interventions might work better than SSRIs for this subgroup of patients.

This is one of those lab tests for mental health that can genuinely change the direction of your treatment. If your hs-CRP is elevated, the conversation shifts from “which medication should we try next?” to “what’s driving this inflammation — and how do we address it?” That’s the kind of question we ask as part of our functional lab testing approach.

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5. Fasting Insulin and Blood Sugar

Your psychiatrist probably isn’t checking your fasting insulin — but they should be. Here’s why: insulin resistance (when your cells stop responding efficiently to insulin) can develop 10–15 years before blood sugar looks abnormal on a standard test. During that time, your brain is already affected. Insulin resistance has been linked to cognitive decline, increased anxiety, depression, and even a reduced ability to form new memories.

A fasting glucose alone isn’t enough. You need fasting insulin (optimal is roughly 2–6 µIU/mL, though many conventional labs consider anything under 25 “normal”) and ideally an HbA1c to see the full picture. Someone with a fasting glucose of 95 and a fasting insulin of 18 has early metabolic dysfunction that a standard panel would miss entirely.

Why does this matter for mental health? Your brain uses about 20% of your body’s glucose. When insulin signaling is impaired, your brain is essentially running on fumes — and it shows up as brain fog, irritability, energy crashes, and mood instability. Addressing metabolic health is a core part of how we practice functional medicine psychiatry because you can’t separate body from brain.

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6. Cortisol (Stress Hormone)

You’ve heard that “stress is bad for you,” but cortisol testing takes that from a vague platitude to actionable data. Cortisol is your primary stress hormone, and its rhythm — high in the morning, tapering through the day — affects energy, sleep, immune function, and mood. When that rhythm is disrupted (either chronically elevated or flatlined from prolonged burnout), psychiatric symptoms follow.

A single morning cortisol blood draw can be a useful starting point, with optimal levels typically between 10–20 µg/dL when drawn before 9 AM. For a more complete picture, a four-point salivary cortisol test maps your entire daily rhythm and can reveal patterns like a blunted morning response (hello, “I can’t get out of bed”) or elevated nighttime cortisol (hello, 2 AM anxiety spiral).

What makes this test valuable is that it connects your lived experience to measurable biology. If you’ve been told your insomnia is “just anxiety” but your nighttime cortisol is elevated, that changes the approach entirely — from a sleep medication to addressing the HPA axis (your body’s stress-response system). It’s one more way our functional lab testing goes beyond symptom management.

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7. Sex Hormones (Testosterone, Estrogen, Progesterone)

If you’ve noticed that your mood shifts dramatically around your period, during perimenopause, or after starting (or stopping) hormonal birth control, this one’s for you. Sex hormones aren’t just about reproduction — they’re deeply involved in serotonin production, GABA activity (your brain’s calming neurotransmitter), and overall nervous system regulation.

Low testosterone in both men and women can show up as depression, low motivation, fatigue, and reduced libido. Progesterone has natural calming, anti-anxiety effects — and its decline during perimenopause is one of the most overlooked drivers of new-onset anxiety and insomnia in women in their late 30s and 40s. Estrogen fluctuations can trigger mood instability that looks exactly like bipolar disorder or treatment-resistant depression.

The problem? Most psychiatrists don’t check hormones and mental health connections. They treat the mood symptoms without asking whether a hormonal shift is the underlying driver. At Willow & Stone, we look at the full picture — including hormone levels drawn at the right time in your cycle — because psychiatric symptoms don’t exist in a vacuum.

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8. Omega-3 Index

This one surprises people, but the research is solid: omega-3 fatty acids (specifically EPA and DHA) play a critical role in brain cell membrane health, inflammation regulation, and neurotransmitter function. An Omega-3 Index test measures the percentage of omega-3s in your red blood cell membranes, giving a reliable picture of your long-term status — not just what you ate last week.

An optimal Omega-3 Index is 8% or above. The average American sits around 4–5%, which is considered deficient. Multiple meta-analyses have found that omega-3 supplementation (particularly EPA at doses of 1,000–2,000 mg/day) can have a meaningful effect on depressive symptoms, especially when used alongside other treatments.

This is one of those blood tests for depression that’s low-risk and high-reward. If your index is low, targeted supplementation is straightforward and affordable. It won’t replace other treatments, but it addresses a biological foundation that many people are missing. We include this as part of our advanced psychiatric lab testing because small nutritional gaps can have outsized effects on how you feel.

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9. Genetic Testing (Pharmacogenomics)

Have you ever been prescribed a medication that either did nothing or hit you with every side effect on the list? You’re not imagining things — your genetics play a significant role in how your body metabolizes psychiatric medications. Pharmacogenomic testing looks at specific gene variants (like CYP2D6, CYP2C19, and others) that affect how quickly or slowly you process certain drugs.

For example, about 7–10% of people are “poor metabolizers” of CYP2D6, which means medications like fluoxetine, paroxetine, or certain pain medications can build up to higher-than-expected levels in their system — leading to more side effects. On the flip end, “ultra-rapid metabolizers” may burn through a medication so fast it never reaches a therapeutic level, making it look like the drug “doesn’t work.”

Genetic testing for mental health doesn’t tell you which medication will definitely work, but it narrows the field significantly. It takes prescribing from trial-and-error to informed decision-making. At Willow & Stone, we offer pharmacogenomic testing because we believe your psychiatric lab work should be personalized — not one-size-fits-all.

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10. Comprehensive Metabolic Panel (With a Closer Look)

You might be thinking, “Wait — my doctor does order a CMP.” And you’re probably right. But there’s a difference between ordering it and actually interpreting it through a functional lens. A standard CMP includes markers like sodium, potassium, glucose, kidney function (BUN, creatinine), and liver enzymes (AST, ALT) — but most providers only flag values that fall outside the lab’s reference range.

Here’s the issue: lab reference ranges are based on the population that gets tested, which includes plenty of unhealthy people. A “normal” result doesn’t necessarily mean “optimal.” For instance, a BUN-to-creatinine ratio can hint at dehydration or protein intake issues affecting neurotransmitter production. Mildly elevated liver enzymes might signal that your body isn’t clearing medications or toxins efficiently. An alkaline phosphatase trending low could point to zinc deficiency.

At Willow & Stone, we don’t just glance at your CMP for red flags — we read it in the context of your full health picture. It’s one piece of our functional medicine psychiatry framework, where every data point is considered alongside your symptoms, history, and goals.

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What to Do Next

If you’ve read through this list feeling a mix of frustration and relief — frustration that nobody has run these tests before, and relief that there might be actual answers — that reaction makes complete sense. You’re not difficult, and your symptoms aren’t “all in your head.” Sometimes the missing piece is a lab test that nobody thought to order.

The good news is that every test on this list is accessible, covered by most insurance plans, and can be drawn with a single blood draw in most cases. You don’t need to overhaul your entire life to get started — you just need a provider who’s willing to look deeper.

At Willow & Stone Health, comprehensive lab work isn’t an add-on. It’s where we begin. Because when we understand what’s happening in your body, we can build a treatment plan that actually fits you — not just your diagnosis code.

Ready to find out what’s really going on? Request your comprehensive lab panel and take the first step toward answers that go beyond a prescription pad.

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Frequently Asked Questions

Does my insurance cover these lab tests?

Most of the tests on this list — thyroid panels, vitamin levels, CMP, fasting insulin, and hs-CRP — are covered by standard health insurance when ordered with an appropriate diagnosis code. Some specialty tests like pharmacogenomic testing or an Omega-3 Index may have variable coverage, but we work with you to maximize what your plan will pay for. We’ll always let you know upfront if something is likely to be out-of-pocket.

Can I ask my current psychiatrist to order these tests?

Absolutely. You can bring this list to any provider and request the tests. Some psychiatrists may not be familiar with ordering the full panel (especially functional markers like hs-CRP or fasting insulin), but your primary care doctor can often help. If you’d like a provider who already builds these into their standard evaluation, that’s exactly what we do at Willow & Stone Health.

How long does it take to get results?

Most standard blood tests come back within 2–5 business days. Genetic testing (pharmacogenomics) typically takes 1–2 weeks. Once your results are in, we schedule a thorough review where we walk through every marker, explain what it means, and discuss how it connects to your symptoms and treatment plan.

What if my labs come back normal?

“Normal” labs are still useful information — they help us rule out biological contributors and focus on other factors like trauma, life stressors, sleep architecture, or medication optimization. That said, we interpret results through functional ranges, which are narrower than standard lab ranges. Something that looks “normal” on paper may still offer clues when read in context.

Do I need to stop my medications before getting tested?

In most cases, no. You should not stop any psychiatric medication without guidance from your provider. For fasting insulin and glucose, you’ll need to fast for 8–12 hours beforehand (water is fine). Cortisol testing requires a morning draw, ideally before 9 AM. We provide specific prep instructions before your lab appointment so everything is accurate.