What each marker actually means.

All the testosterone in your blood (bound + free). The most common androgen marker.

When it matters: Below 264 on a clean baseline warrants a workup. Above 1500 is rarely the danger itself — what matters is downstream (E2, HCT, lipids).

The unbound, bioactive fraction of testosterone — the part that actually does work at receptors.

When it matters: Symptoms (low libido, low energy, brain fog) track free T better than total T. A total that looks fine with low free often explains persistent symptoms.

The active estrogen in men and women. Use the LC/MS "sensitive" assay — the standard ELISA reads inaccurately at the low end.

When it matters: Below 12 on an AI is over-suppression — joint pain, libido crash, lipid harm. Above 60 is gyno territory for many. Single values are noisy; confirm with repeat before acting.

Sex hormone binding globulin — the liver-made protein that grabs sex hormones and parks them in circulation. Sets how much T runs free.

When it matters: Crushed SHBG (under 10) with high free T can produce androgen-overload symptoms even when total T looks normal. Very high SHBG can make the opposite — low symptoms with adequate total T.

A pituitary hormone — its job is lactation, but in men elevated levels cause low libido, ED, and gyno.

When it matters: Above 25 with 19-nor compounds usually gets clinical attention. Above 50 without an obvious driver warrants a pituitary MRI workup. Single values are very noisy — always confirm.

Luteinizing hormone — the pituitary signal that tells testes to make testosterone.

When it matters: Low LH with low T = secondary hypogonadism. High LH with low T = primary. Recovery monitoring after a cycle tracks LH first, T second.

Follicle stimulating hormone — pituitary signal for sperm production in men, ovarian function in women.

When it matters: Fertility on enhanced protocols tracks FSH closely — full suppression for years can mean delayed sperm production recovery, sometimes permanent.

Insulin-like growth factor 1 — what GH actually does its work through. Liver-made in response to GH.

When it matters: On GH, IGF-1 reads the product. Sub-150 on a real GH protocol suggests under-dosed or counterfeit. Sustained >500 has its own risks (organ growth, glucose handling).

Dehydroepiandrosterone sulfate — the long-lived adrenal androgen precursor. Stable enough to read adrenal output.

When it matters: Low DHEA-S often tracks with chronic overtraining or under-recovery. Not a single-marker diagnosis — pair with cortisol pattern.

The primary stress hormone. Highly diurnal — values are only meaningful from a fasted morning draw.

When it matters: Above 25 AM is high stress. Below 6 with symptoms (fatigue, low BP, salt cravings) needs an adrenal workup.

Thyroid-stimulating hormone. Pituitary turns this up when the thyroid is making too little; down when it's making too much.

When it matters: TSH alone can mislead — always pair with Free T4 and ideally Free T3. Above 4 with low FT4 is overt hypo. High TSH with normal FT4 is subclinical.

The unbound, bioactive thyroxine fraction — the storage form of thyroid hormone. Gets converted to T3 in tissues.

When it matters: On T4 replacement, target the upper half of the range. Low FT4 with elevated TSH = primary hypothyroidism.

The active thyroid hormone — what your tissues actually use. T4 gets converted to T3 (or to reverse T3 under stress).

When it matters: Low FT3 explains a lot of "tired with normal TSH" presentations. Worth checking before chalking it up to lifestyle.

An inactive isomer of T3. The body shunts T4 → rT3 (instead of T3) under stress or severe restriction — "non-thyroidal illness syndrome."

When it matters: Elevated rT3 with low-normal FT3 can explain "metabolism shut down" symptoms during aggressive diets or overtraining periods.

The sum of HDL + LDL + (triglycerides/5). Less useful than its components — look at HDL, LDL, and ApoB separately.

When it matters: Total cholesterol in isolation tells you less than the ratio (HDL:LDL) and the ApoB. Don't over-react to total alone.

The "good" cholesterol — actually a lipoprotein that ferries cholesterol back to the liver for clearance. Higher = better cardiovascular profile.

When it matters: HDL below 40 is a real cardiovascular risk signal. On orals it's expected; off-cycle recovery is often months, not weeks.

The "bad" cholesterol — carries cholesterol from liver to tissues, can deposit in arterial walls. Direct lipoprotein particle count (ApoB) is the more modern measure.

When it matters: Over 130 is elevated; over 160 is high. Pair with ApoB and Lp(a) for the modern cardiovascular picture.

Storage fat in circulation. Affected by recent meals — fasted draw matters.

When it matters: Confirm fasted draw before reacting. Above 200 fasted is clinically meaningful and often paired with insulin resistance.

Apolipoprotein B — counts the actual number of atherogenic lipoprotein particles. Better cardiovascular risk predictor than LDL.

When it matters: Every ApoB particle is one risk-bearing particle. The modern target for high-risk patients is well under 80. If LDL looks fine but ApoB is high, the LDL number was misleading.

Lipoprotein(a) — a genetically determined, independent cardiovascular risk factor. Mostly fixed for life; can't move it much with diet or exercise.

When it matters: Worth measuring once. Over 75 is significant. Doesn't need annual re-testing. If high, push the levers you can (ApoB, BP) more aggressively.

Glucose after 10+ hours fasted. The classic diabetes screening marker.

When it matters: Over 99 is pre-diabetic; over 125 is diabetic on repeat. HbA1c is the better long-term gauge.

How hard your pancreas is working at rest to keep glucose down. Sensitive early marker of insulin resistance.

When it matters: Fasting insulin >12 with normal glucose is early insulin resistance — glucose looks fine because insulin is working overtime.

Glycated hemoglobin — a 3-month average of blood glucose. Less noisy than single fasting glucose readings.

When it matters: Over 5.7 is pre-diabetic by ADA. Trend across draws is more telling than a single value.

High-sensitivity C-reactive protein. An inflammation marker — chronic low-grade inflammation predicts cardiovascular events.

When it matters: Above 3 chronically is a real CV risk signal. Confirm the value isn't from an acute infection before drawing conclusions.

Alanine aminotransferase — liver enzyme. More specific to liver than AST. Elevations track hepatocellular stress.

When it matters: Over 80 on orals is common but worth tracking. Over 150 even on orals warrants pause + recheck after a rest period.

Aspartate aminotransferase — found in liver, muscle, and heart. Less liver-specific than ALT.

When it matters: AST > ALT pattern often points to muscle source. ALT > AST with both elevated points more to liver. The ratio matters as much as the absolute values.

Gamma-glutamyl transferase — a more specific liver/bile-duct marker than ALT or AST. Less affected by exercise.

When it matters: Useful for distinguishing muscle vs. liver source when ALT/AST are elevated — if GGT is also up, it's pointing at liver.

A muscle-breakdown byproduct that the kidneys clear. Used to calculate eGFR. Reads higher in muscular people regardless of kidney status.

When it matters: In a muscular lifter, a creatinine slightly above range is usually muscle mass, not kidney trouble. Cystatin C is a better kidney measure in this context.

Estimated glomerular filtration rate — calculated kidney function from creatinine. Under-reads in muscular people because creatinine is artificially elevated.

When it matters: eGFR below 60 meets the chronic-kidney-disease threshold — but a cystatin C-based eGFR usually reads higher in muscular people and is more accurate.

The percentage of blood volume that's red cells. Tracks blood viscosity — too high raises stroke and clot risk.

When it matters: Above 52% gets clinical attention. Above 54% most physicians prescribe phlebotomy. Donating blood drops it quickly and reliably.

The oxygen-carrying protein in red cells. Tracks closely with hematocrit — usually moves together.

When it matters: Reads in parallel with HCT. Above 18 is high enough that action (donation or phlebotomy) is usually recommended.

Red blood cell count. Third member of the HCT/HGB/RBC trio — all three usually move together.

When it matters: Pair with MCV (cell size) for a richer read — high RBC + low MCV can mean thalassemia trait.

White blood cell count — total immune cells in circulation.

When it matters: Persistent below 3.4 or above 11 warrants a workup; transient changes are very common around training or minor illness.

Cell fragments that handle clotting. Both ends of the range matter clinically.

When it matters: Repeat low-platelet readings need a workup. Acute infections often raise platelets transiently — not a long-term concern.

Mean corpuscular volume — average red cell size. Tells you what kind of anemia you might be looking at.

When it matters: MCV out of range almost always points to a specific cause — high suggests B12/folate workup; low suggests iron status.

The body's iron storage protein. Low ferritin = iron deficient even before frank anemia. Also an acute-phase reactant — inflammation raises it.

When it matters: Below 30 is iron-deficient even with normal hemoglobin. Common in regular donors. Above 300 chronically warrants ruling out hemochromatosis.