Bloodwork & Biomarkers

The OPTN canonical reference on male bloodwork and biomarkers. Living document. Articles link here when they need to point at the deep mechanism behind a marker. This page is intended to grow over time. Last meaningful expansion: 2026-04-07.

What to test (the OPTN baseline panel)

A useful baseline panel for any man over 30 includes total testosterone, free testosterone (calculated or measured), SHBG, estradiol (sensitive assay), LH, FSH, hematocrit, prolactin, a full lipid panel, fasting glucose, HbA1c, and a basic metabolic panel. Direct-to-consumer labs like Ulta Lab Tests, Marek Health, and DiscountedLabs let you order most of this without a prescription in most US states.

For men already on TRT, add: PSA (prostate-specific antigen) once a year, DHT if symptoms suggest it, and a CBC every 3-6 months for hematocrit monitoring.

For men with metabolic concerns, add: fasting insulin, ApoB, Lp(a), and a thyroid panel including TSH, free T3, and free T4.

Total testosterone

What it is: the total amount of testosterone circulating in your bloodstream, measured in nanograms per deciliter (ng/dL). The marker your PCP runs by default and the one most clinics anchor on.

US reference range: roughly 264 to 916 ng/dL on most labs (LabCorp, Quest). Wider on some, narrower on others.

The level at which most men feel best is the upper third of the reference range, somewhere between 600 and 900 ng/dL. The reference range is a population statistic, not a clinical target. Read it as descriptive, not prescriptive.

The trap with total T: it does not account for binding. A man with a total T of 550 and high SHBG can feel worse than a man with a total T of 400 and low SHBG. Same number on the page, completely different functional levels.

SHBG and free T

Sex hormone binding globulin (SHBG) is the glycoprotein that binds testosterone in the bloodstream. Bound testosterone is not biologically active. Only the unbound (free) fraction is.

SHBG reference range: roughly 10 to 57 nmol/L. The useful zone for most men is 20 to 45.

What pushes SHBG up: aging, alcohol, low calorie intake, hyperthyroidism, liver issues, anorexia, oral estrogens.

What pushes SHBG down: insulin resistance, obesity, hypothyroidism, anabolic steroid use, exogenous testosterone (TRT often suppresses SHBG over time), Cushing’s syndrome.

SHBG is partly genetic. Some men run high or low for life regardless of intervention. The protocol has to be dialed around the SHBG you have, not the SHBG you wish you had.

Free T calculation methods

Most labs report free T as a calculation derived from total T, SHBG, and albumin. The standard formula is the Vermeulen calculation. It is reasonably close to direct measurement (equilibrium dialysis) for most men but can be off at the edges of the range.

Three ways to get a free T number, in order of accuracy:

1. Equilibrium dialysis (gold standard). Direct measurement. Slow, expensive, accurate. Order this if a real decision rides on a borderline number.
2. Calculated free T (Vermeulen formula). Standard at most labs. Uses total T + SHBG + albumin. Close enough for most clinical purposes.
3. Direct analog immunoassay. The least reliable. Avoid if possible. If your lab only offers this, request a different lab or a calculated number.

If your panel only shows total T and not free T (calculated or measured), you are reading half the book. Always order both.

Estradiol (sensitive assay)

Yes, men make estrogen. Yes, you need it. Estradiol in men is derived primarily from aromatization of testosterone. It matters for bone density, cardiovascular health, libido (yes, libido), joint function, and cognition.

The single most important thing about reading an estradiol number for a man is making sure it was run on a sensitive assay (LC-MS/MS), not a standard immunoassay. Standard immunoassay is unreliable at the low concentrations men typically run. If your panel says “estradiol” and gives a number under 15 with no notation about the assay, you cannot trust it.

What to look for on a sensitive assay:

• 20 to 40 pg/mL is the zone where most men feel and function their best
• Below 15 is “crashed E2”: joint pain, libido crash, mood issues, fatigue
• Above 60 starts to show water retention, mood instability, gynecomastia risk

The forums will tell you to drive E2 lower with an aromatase inhibitor. The forums are wrong for most men. Crashed E2 feels worse than slightly elevated E2 and the long-term consequences (bone density, cardiovascular, joint health) are worse too.

LH and FSH

Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are the pituitary hormones that signal the testes to produce testosterone and sperm. They tell you whether the signal is intact.

For a man not on TRT with low testosterone:

• High LH, low T: primary hypogonadism. The testes aren’t responding to the signal. The pituitary is shouting and nothing is happening. Causes include genetic conditions, testicular damage, mumps, chemotherapy.
• Low LH, low T: secondary hypogonadism. The pituitary isn’t sending the signal in the first place. Causes include hypothalamic or pituitary issues, anabolic steroid history, obesity, sleep apnea, chronic stress, opioid use.
• Normal LH, low T: ambiguous. Worth investigating.

For a man on TRT, both LH and FSH are suppressed because exogenous testosterone tells the pituitary to stop signaling. This is expected. It is also why TRT suppresses fertility and why men who want kids should talk about HCG, enclomiphene, or other fertility-preserving options before starting.

Hematocrit and red blood cell mass

Hematocrit is the percentage of your blood volume that is red blood cells. Testosterone stimulates red blood cell production via erythropoietin, so hematocrit drifts up on TRT. This is one of the safety markers most TRT clinics check at baseline and then forget about.

Reference range: roughly 38 to 50 percent for men.

• Under 52: generally considered safe
• 52 to 54: warning zone, look at hydration, dose, donation frequency
• Above 54: most providers recommend therapeutic phlebotomy (a blood draw to bring it back down)

The fix is usually simple: donate blood quarterly, drink more water, sometimes lower the TRT dose. The problem is that nobody catches it if nobody is watching.

Prolactin

Prolactin is the pituitary hormone associated with lactation in women but is also relevant in men. Elevated prolactin can suppress testosterone production by interfering with GnRH signaling.

Reference range: roughly 4 to 15 ng/mL for men.

When to test: if you have low testosterone with low LH and FSH (secondary hypogonadism pattern) and you cannot find an obvious cause, check prolactin. A pituitary microadenoma is a treatable cause that gets missed if no one looks.

DHT (dihydrotestosterone)

DHT is a more potent androgen converted from testosterone via 5-alpha-reductase. It matters for libido, prostate function, and (relevantly for some men) hair loss.

Most men do not need to track DHT routinely. Test it if:

• You are losing hair and want to understand whether DHT is elevated
• You are using a 5-alpha-reductase inhibitor (finasteride, dutasteride) and want to confirm it’s working
• You are using transdermal testosterone, which converts to DHT at higher rates than injection

Lipid panel and metabolic markers

A male hormone panel without a metabolic panel is incomplete. The four cardiovascular markers worth tracking:

1. ApoB: the most predictive single marker for atherosclerotic cardiovascular disease risk. Better than LDL alone.
2. LDL-C and non-HDL-C: standard but worth tracking for trend.
3. Triglycerides and HDL ratio: metabolic health indicator.
4. Lp(a): genetic, test once in a lifetime, dictates risk baseline.

Fasting glucose and HbA1c round out the picture. Insulin resistance suppresses SHBG, lowers free T indirectly, and is a major confounder for any man trying to dial in a hormone protocol while metabolic health is unaddressed.

How often to test

• Baseline before starting any protocol
• 6 weeks after any dose change (testosterone takes that long to reach a new steady state)
• Quarterly once dialed in
• Annually for the full metabolic and lipid panel alongside the hormone panel
• More often if anything is changing rapidly or symptoms are off

Timing your draw

Testosterone follows a circadian rhythm. Levels are highest in the morning and decline through the day. Get drawn before 10 AM. Be fasted. Do not have a hard training session the day before. Hydrate normally.

For men on weekly injection, time the draw at the trough (the day before the next injection) and measure both peak and trough on at least one panel to know your range.

For consistent results across panels, always draw at the same approximate time. Otherwise you are measuring noise.

Building your own dataset

The single most useful practice is keeping a running spreadsheet of every panel over time. Date, total T, free T, SHBG, E2, LH, FSH, hematocrit, lipids, fasting glucose, and notes about how you felt that month. One panel is a snapshot. Twelve months of panels is a trajectory. The trajectory is what tells you whether things are moving and why.

Sources and further reading

This wiki will accumulate primary sources over time. Initial references:

• Bhasin S, et al. “Reference Ranges for Testosterone in Men Generated Using Liquid Chromatography Tandem Mass Spectrometry in a Community-Based Sample of Healthy Nonobese Young Men in the Framingham Heart Study.” J Clin Endocrinol Metab. 2011.
• Endocrine Society Clinical Practice Guideline: Testosterone Therapy in Men with Hypogonadism (most recent revision).
• Vermeulen A, Verdonck L, Kaufman JM. “A critical evaluation of simple methods for the estimation of free testosterone in serum.” J Clin Endocrinol Metab. 1999.