The Most Common Lab Tests I Recommend To Nutrition Patients

Here’s one big benefit to working with a nutritionist instead of trying to follow trends and fad diets: I always send patients to their primary care doctor or to a nurse practitioner for lab tests (I cannot run them myself) to see where you’re not getting enough nutrients and get a more holistic view of what your body might need. This is essential to figuring out what works for you instead of assuming that trendy diet is right for everybody.

This is how I get a baseline with my patients. And some lab values may appear normal, but that doesn’t mean there’s nothing you can do to address issues. How many times have you gone to a doctor and they run a few tests just to say “you’re fine”? That’s not how I work. Some of your lab results may be a little too high or low, and I work with “ideal ranges” for certain tests. There’s also the possibility that some medications can alter vitamins/minerals levels –– so this is why looking at a full history helps. 

I honestly think everyone should have lipids, fasting glucose, HgbA1c, Vitamin D, B12, Ferritin, TSH, eFGR performed yearly. That is literally preventative medicine. Countless times I have found vitamin deficiencies or elevated HgbA1c in patients that have never been tested. And most of the time the fixes are so easy. Also, seeing lab improvements is the most satisfying thing ever to me.

So here’s a rundown of everything I test for. You can even ask your doctor to run the same tests if you’re suspicious that one of these levels may be an issue for you.

Metabolic & Cardiovascular Health

1. Lipid Panel
Why: Evaluates total cholesterol, LDL, HDL, and triglycerides to assess cardiovascular risk and metabolic health. Can help us figure out what direction to move in re: nutrition therapy.

2. Fasting Glucose
Why: Screens for impaired glucose metabolism, diabetes, or prediabetes. A key baseline marker. Affected by so many things other than food (stress, sleep, illness, etc.)

3. Fasting Insulin
Why: Assesses insulin sensitivity and helps detect early insulin resistance — especially important in metabolic syndrome, PCOS, and suspected insulin-glucose imbalance.

4. Hemoglobin A1c (HgbA1c)
Why: Reflects average blood glucose over the past 2–3 months; useful for diagnosing and monitoring diabetes.

5. C-Reactive Protein (CRP), high sensitivity (hs-CRP)
Why: A marker of chronic low-grade inflammation and cardiovascular risk.

6. Microalbumin (if patients has/may have diabetes)
Why: Detects early kidney damage in diabetes. Elevated levels indicate microvascular complications, even before serum creatinine or eGFR are abnormal.

Nutrient & Micronutrient Status

7. Vitamin D (25-hydroxyvitamin D)
Why: Supports immune function, bone health, and inflammation regulation. Commonly deficient.

8. Vitamin B12
Why: Crucial for neurological function and red blood cell production. Deficiency can cause anemia and neuropathy. Some medications like metformin can lead to deficient levels (in the nutrition world < 600 pg/mL)

9. Folate (Vitamin B9)
Why: Essential for DNA synthesis, red blood cell production, and reducing homocysteine (a cardiovascular risk factor).

10. Ferritin
Why: Reflects iron stores. Low levels suggest iron deficiency anemia; high levels may indicate inflammation or iron overload.

Thyroid & Hormonal Health

11. Thyroid Stimulating Hormone (TSH)
Why: Screens for thyroid dysfunction (hypo- or hyperthyroidism), which impacts metabolism, mood, and energy.

12. Free and Total Testosterone (if PCOS suspected)
Why: Assesses androgen levels in suspected PCOS. Elevated levels can contribute to symptoms like acne, hirsutism, and menstrual irregularities.

13. DHEA-Sulfate (DHEAS) (if PCOS suspected)
Why: Androgen produced by the adrenal glands. Elevated levels help differentiate adrenal vs. ovarian sources of androgen excess in PCOS.

Electrolytes & Kidney/Liver Function

14. Potassium
Why: Key for heart rhythm, nerve, and muscle function. Imbalances can indicate renal, adrenal, or medication-related issues.

15. Calcium (total and/or ionized)
Why: Important for bone health, muscle contraction, and nerve signaling. Abnormal levels may reflect parathyroid, kidney, or vitamin D issues.

16. Magnesium
Why: Supports energy production, glucose metabolism, and muscle/nerve function. 

17. Liver Function Tests (LFTs)
Why: Measures liver enzymes (ALT, AST), bilirubin, and proteins to assess liver health and detect fatty liver, inflammation, or damage.

18. Estimated Glomerular Filtration Rate (eGFR)
Why: Measures kidney function. Useful for early detection of chronic kidney disease, especially in diabetics or those on nephrotoxic medications.

Do some doctors or nurse practitioners poopoo my lab recommendations? Yup. But most are coming around. It’s super frustrating for everyone involved. 

I suspect I see major changes in lab results during transitional times (changing decades, school → work, before children → after children, stressful periods, perimenopause, postmenopause, etc. I can’t confirm this with data, but that’s just my experience, anecdotally.

Getting these tests are helpful for knowing how to proceed so you can live a happier and healthier life. 

If you’re in New York or New Jersey, you can see for yourself: Book an appointment with me!