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Decode Biomarkers

Your blood work, in plain English.

Twenty-two biomarker explainers. What each one measures, what the ranges generally mean, and what to ask your healthcare provider — without the clinical jargon and without the wellness hype.

22 biomarkers explained Editorially reviewed Updated quarterly Sources cited

Heme doesn't diagnose. These guides explain what each marker is, what ranges generally mean, and what to discuss with your provider. They are not a substitute for personal medical advice.

Browse all 22 →

Iron & energy.

The biomarkers most often behind unexplained fatigue, hair shedding and exercise intolerance in women.

FE STORAGE Ferritin Your iron savings account. The single most useful number for low-iron symptoms in women. Decode SERUM IRON Iron Iron in circulation right now. Useful only with ferritin and transferrin saturation. Decode VITAMIN B12 B12 Nerve and energy production. Low in vegetarians, postpartum and over-50s. Decode FOLATE / B9 Folate Cellular repair and pregnancy support. Often deficient before B12 is. Decode

Thyroid panel.

The full panel — not just TSH. What your thyroid markers actually tell you, in plain English.

PITUITARY SIGNAL TSH The brain's signal to the thyroid. The most common starting test, but not the full story. Decode ACTIVE THYROID Free T3 The active thyroid hormone — what your cells actually use. Decode THYROID RESERVE Free T4 The thyroid's storage form, converted into T3 as needed. Decode TPO / TgAb Thyroid antibodies Often missed. The marker that confirms autoimmune (Hashimoto's) thyroid disease. Decode

Hormones & cycle.

The reproductive panel that matters for cycle, fertility and perimenopause — and the timing rules that change interpretation.

PRIMARY ESTROGENEstradiolThe main estrogen women track. Levels swing through the cycle and decline through perimenopause.Decode CYCLE HORMONEProgesteroneTested mid-luteal to confirm ovulation. Critical for fertility and cycle symptoms.Decode OVARIAN SIGNALFSHTracks ovarian function. Rising FSH is one of the earliest signs of perimenopause.Decode OVULATION TRIGGERLHSurges at ovulation. Together with FSH gives the LH:FSH ratio — useful for PCOS.Decode ANDROGENTestosterone (women)Women have it too — and it matters for libido, mood, muscle and PCOS.Decode ADRENAL ANDROGENDHEA-SA precursor hormone from the adrenals. Often tested alongside testosterone for PCOS.Decode STRESS HORMONECortisolThe stress hormone. Pattern matters more than a single number — best tested at multiple times.Decode AMHAMH (ovarian reserve)The fertility marker most often misinterpreted. What it tells you and what it doesn't.Decode

Metabolic & inflammation.

The markers that flag long-term risk — blood sugar regulation, cardiovascular health and chronic inflammation.

INFLAMMATIONCRP / hs-CRPA general marker of inflammation. High-sensitivity CRP is the version that matters for cardiovascular risk.Decode 3-MONTH GLUCOSEHbA1cYour average blood sugar over the past 3 months. The standard screen for prediabetes.Decode INSULINFasting insulinMore sensitive than glucose for early metabolic dysfunction. Often missed in standard panels.Decode LIPID PANELCholesterolTotal, LDL, HDL, triglycerides — and why the simple "good vs bad" framing is outdated.Decode CARDIAC RISKApoBThe cardiovascular risk marker more accurate than LDL alone. Newer, increasingly recommended.Decode VITAMINVitamin D25-hydroxyvitamin D — the form lab reports use. Low in most American women in winter.Decode MINERALMagnesiumStandard serum tests miss intracellular magnesium. Worth a deeper look if symptoms persist.Decode PROLACTINProlactinElevated prolactin can disrupt cycles and fertility. Worth testing when periods are irregular.Decode
Foundations

"In range" doesn't always mean optimal.

Reference ranges are calculated from broad population statistics, not from "at what level do women feel well." A growing body of clinical writing argues that functional deficiency — symptoms despite an "in range" number — can begin well above the lab cutoff, particularly in women who menstruate.

This is the conversation worth having with your provider: not just "is my number in range" but "is my number consistent with how I'm feeling, and is it where you would want it for someone in my situation?"

See how this plays out with ferritin — the women's health marker most often dismissed as fine →

Educational only. Not medical advice. Biomarker explainers on Heme are general education, reviewed for accuracy by qualified clinicians. Always speak with a qualified healthcare provider about symptoms, lab results or treatment decisions — particularly if you are pregnant, breastfeeding, take medication, or have an existing medical condition.