What Should I Test First? Start From Your Symptom

Feeling off, and not sure which test to ask for?

Start with the symptom that’s costing you the most. Each one below has a short list of tests worth asking for by name.

Most are simple blood tests, and many of them are standard markers insurance often covers.

Key Insight:

↳ Pick one symptom. Order the tests on that row, and wait for those results before chasing the next one.

↳ For most symptoms, the most common cause isn’t a nutrient. Each row names what else to rule out.

↳ Correct one thing at a time, then retest. Nutrients affect each other, so stacking supplements can blur the picture.

Why It Matters:

↳ A short, specific list tends to get better answers than “check everything.”

↳ It can save you months, plus the money spent on products that don’t fit what’s going on.

Start From Your Symptom:

↳ Why am I tired all the time? Test first: ferritin with CRP, transferrin saturation, a CBC, B12, 25-hydroxyvitamin D, and TSH with free T4. In randomized trials, iron improved fatigue in iron-deficient women even without anemia. Also rule out: sleep apnea, which can look exactly like this.

↳ Why won’t the brain fog lift? Test first: B12 with methylmalonic acid, ferritin with CRP, TSH with free T4, vitamin D and homocysteine. B12 and iron are both reversible when they’re caught. Also rule out: sleep problems, perimenopause and ADHD. A nutrient check and an ADHD evaluation aren’t either-or.

↳ Could a deficiency affect my mood? It can play a part. Test first: vitamin D, B12 with methylmalonic acid, RBC folate, ferritin, TSH and RBC magnesium. Do this alongside care for your mood, not instead of it. If you’re in crisis, contact a clinician or a crisis line today.

↳ Can’t sleep, or keep your legs still? Test first: ferritin and transferrin saturation. For restless legs, guidelines treat with iron at a ferritin of 75 ng/mL or lower. For sleep in general, insomnia therapy (CBT-I) has the strongest evidence of anything here, and a bigger melatonin dose doesn’t work better.

↳ Why do I get sick so often? Test first: a CBC with differential, vitamin D, zinc with copper and CRP, ferritin and HbA1c. Zinc lozenges made colds 33% shorter at more than 75 mg of zinc per day, started within about 24 hours. Lower doses didn’t help, and that dose is for a few days, not a habit. Also rule out: undiagnosed diabetes, and plain exposure if you live with small kids.

↳ Why won’t the weight move? It’s physiology, not a willpower test. Test first: HbA1c, fasting insulin and glucose, TSH with free T4, vitamin D, RBC magnesium, and B12 if you take metformin. Also rule out: PCOS, sleep, and medication effects.

↳ Why do I hurt everywhere? Test first: vitamin D, RBC magnesium, B12 with methylmalonic acid, ferritin, TSH, and a look at your total B6 from every product. Low vitamin D causes bone and muscle pain that fully reverses. Labs normal? Fascia and pain sensitivity are where to look next.

↳ Is this my thyroid? Test first: TSH with free T4, thyroid antibodies, ferritin and vitamin D. Taking biotin? Stop before testing, because it can skew thyroid results.

↳ Is this perimenopause, or something else? Test first: ferritin with CRP, TSH with free T4 and antibodies, vitamin D and B12. Cycles often get heavier before they spread out, which drains iron, and low iron and thyroid issues can look almost the same. Perimenopause itself has real treatments, including hormone therapy, worth a real conversation.

↳ Why am I struggling to conceive? Test first: ferritin with CRP, vitamin D, RBC folate, TSH with free T4 and thyroid antibodies, and B12. Start folate before you try, not after a positive test. Do this alongside a full fertility workup, not instead of it, because time matters, especially after 35.

↳ Am I losing bone? Test first: vitamin D, calcium, parathyroid hormone, kidney function, and a DEXA scan if your age or risk calls for it. Protein and resistance training have the strongest evidence. Large trials haven’t shown that big calcium doses reliably cut fractures, so food first is the better default.

Why This Isn’t Everywhere:

↳ An appointment is built to answer one question well. A symptom that could come from 4 different systems needs 4 questions in one short visit, and the time isn’t there. A short list you bring with you makes the time you do get count.

Why It’s a Win-Win I Wanted to Surface:

↳ You get a place to start today, without guessing.

↳ Your clinician gets a focused request with a reason behind each test.

↳ Your household gets answers sooner, and fewer bottles that weren’t the answer.

We Actually Have a Book on This

Chapter 11 of The Root Cause of Your Symptoms, Uncovered, “My Symptom Is X. What Should I Test First?”, gives every row in full: the tests, the real evidence, the noise, and the non-nutrient causes. “What to Say to Your Clinician” puts the scripts on one page.

Learn more about the book

Where the Numbers Come From

↳ Restless legs: IRLSSG, 2018 and AASM, 2025.

↳ Zinc lozenges: Hemilä, JRSM Open, 2017.

↳ Melatonin and insomnia: AASM guideline, 2017 and American College of Physicians guideline, 2016.

↳ Everything else: The Root Cause of Your Symptoms, Uncovered, 2nd edition, Chapter 11.

↳ Educational content. Keryn Gold holds a PhD in Biomedical Sciences, not a medical license. Not medical advice.

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If one of these symptoms lifted tomorrow, what would you do with the energy?