A plain-language guide to men's hormone panels: total and free testosterone, SHBG, LH, FSH, estradiol, and the patterns that point to primary versus secondary hypogonadism.
A plain-language guide to men's hormone panels: total and free testosterone, SHBG, LH, FSH, estradiol, and the patterns that point to primary versus secondary hypogonadism.
A hormone lab report is a snapshot, not a verdict. The numbers tell you where you landed on a given morning, in a given lab's reference system, under conditions that matter more than most patients realize. One number alone, without context, rarely tells you whether you need treatment.
A standard men's hormone panel typically includes several values working together:
Here is the problem with reading just one column: reference ranges vary by lab, by age, and by metabolic health. A large cross-sectional study of nearly 200,000 men found significant variation in serum testosterone based on time of blood draw and the presence of metabolic syndrome, making a single fasting result harder to interpret in isolation [1]. Free testosterone, measured precisely by equilibrium dialysis, follows its own age-stratified curve, with a reference range of 184 to 749 pmol/L in healthy, non-obese men aged 18 to 39 [2]. Calculated free testosterone, the version most labs report, offers a reasonable approximation but carries known limitations in accuracy [3].
What you need is not just the numbers, but a framework for what each number actually measures, and that starts with understanding total versus free testosterone.
Total testosterone is the number printed in bold on most lab reports, but it is not the number that runs your energy, libido, or mood. Only the fraction your body can actually use matters, and that fraction is called free testosterone.
Think of testosterone like money in a bank account. Total testosterone is your account balance. Free testosterone is the cash in your wallet, what you can spend today. Most of the testosterone circulating in your blood is locked up, bound to proteins that carry it around but prevent it from entering cells and doing anything useful. The leftover fraction, roughly the portion not tightly bound, is what your tissues respond to.
The main binding protein is SHBG, short for sex hormone-binding globulin. Picture it as a transport protein with a very strong grip: testosterone bound to SHBG is biologically inactive, meaning your cells cannot read it or use it. A smaller share binds loosely to albumin, a protein with a weaker hold, and that loosely bound portion plus the free fraction together make up what labs call bioavailable testosterone, the total amount your body can actually access [3].
SHBG levels shift with age, body weight, and metabolic health [3]. Men with obesity show measurably lower free testosterone even when total testosterone sits in the normal range, because metabolic changes reduce SHBG [4]. The reverse is also true: a man with high SHBG can look fine on total testosterone while functioning well below his actual physiologic need.
A 2024 review confirmed that free testosterone serves as a second-line indicator of androgen exposure precisely because SHBG fluctuations can make total testosterone misleading [3]. In men where bioavailable testosterone is low, symptoms of androgen deficiency can appear even when the total number is technically normal [5].
| Measure | What it counts | Clinical limitation |
|---|---|---|
| Total testosterone | All circulating T, bound and free | Can miss functional deficiency when SHBG is high or low |
| Free testosterone | Unbound, immediately active T | Requires accurate SHBG for calculation; calculator choice matters |
| Bioavailable testosterone | Free T plus albumin-bound T | Closest proxy to tissue-level androgen exposure |
Understanding what TRT actually replaces starts here: if the wrong number is being treated, the wrong decision follows. The next biomarker
Two numbers on your panel answer the most important diagnostic question: is the problem in the testes, or is the brain not sending the right signal? LH (luteinizing hormone) and FSH (follicle-stimulating hormone) are the messengers your pituitary gland fires down to the testes. When testosterone is low, where you find these two numbers tells a physician exactly where the breakdown is happening.
Think of LH as a text message from your brain saying "make more testosterone." When the testes are damaged or failing, the brain sends that message louder and louder. A high LH paired with low testosterone means the pituitary is doing its job, but the testes are not responding. This pattern is called primary hypogonadism, meaning the failure lives in the testes themselves [6]. FSH follows a similar logic: elevated FSH alongside small or soft testes points toward reduced testicular reserve, the remaining capacity to produce both testosterone and sperm [7].
Put plainly: high LH + low T means the factory is broken, not the order form.
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The mirror pattern is secondary hypogonadism. Here, testosterone is low and LH is also low or inappropriately normal, meaning the pituitary or hypothalamus, the brain regions that sit above the pituitary in the hormonal chain, never sent a strong enough signal to begin with [6]. The testes may be perfectly capable of producing testosterone; they simply never received the instruction. Common reversible causes include obesity, opioid use, and elevated prolactin [6].
Put plainly: low LH + low T means the order form was never sent, not that the factory is broken.
| Pattern | LH | FSH | What it suggests |
|---|---|---|---|
| Primary hypogonadism | High | High | Testicular failure; brain signaling is intact |
| Secondary hypogonadism | Low or normal | Low or normal | Brain or pituitary not signaling adequately |
| Normal | Mid-range | Mid-range | No clear central or gonadal failure |
This distinction shapes every treatment conversation. A man with age-related questions about starting TRT and secondary hy
Most men are surprised to see estradiol on their lab report. It belongs there. Estradiol, the primary form of estrogen in men, is made when the enzyme aromatase converts testosterone into estrogen inside fat tissue, the liver, and the brain. Men need some of it to maintain bone density, protect the heart, and keep libido working [6].
The amount that shows up on your report depends heavily on how it was measured. A standard estradiol assay, the one most general labs run, is calibrated for women's higher levels and can return inaccurate readings at the lower concentrations typical in men. A sensitive estradiol assay, sometimes labeled "LC-MS/MS" or "ultrasensitive," is the right tool for a men's panel. If your lab used the standard version, the number may not reflect reality.
Aromatization, the conversion process, runs faster when body fat is higher, because fat tissue carries more aromatase. More fat means more conversion, which means estradiol can climb even when testosterone is low [6]. The table below captures what each direction looks and feels like.
| Estradiol pattern | Common symptoms | Lab context |
|---|---|---|
| Too high | Water retention, soft fat gain around the chest, reduced morning erections, emotional flatness | Often seen with elevated BMI or high-dose TRT |
| Too low | Joint aches, low libido despite normal total T, mood dips, poor bone support | Can follow over-aggressive aromatase inhibitor use |
Put plainly: estradiol too high feels like too much estrogen; estradiol too low feels like you dried everything out.
For a fuller picture of how estradiol and testosterone interact across the whole panel, estradiol and testosterone in men goes deeper on the relationship. The next piece of the report, the one most men overlook entirely, is the pattern formed when you read LH, FSH, and testosterone together.
Your individual numbers mean more when you read them as a group. A testosterone level sitting at 280 ng/dL tells one story if LH is sky-high and a completely different story if LH is barely detectable. The pattern is the diagnosis, not any single value.
A 2026 JAMA review confirmed that hypogonadism requires "consistently low morning serum testosterone concentrations" alongside signs and symptoms, and that FSH and LH must be measured to tell primary from secondary hypogonadism apart [6]. Put plainly: the pituitary signals (LH and FSH) tell you whether the problem is upstream in the brain or downstream in the testes.
| Panel Pattern | What It Looks Like | Plain-Language Meaning | Typical Next Step |
|---|---|---|---|
| Low T, high LH, high FSH | Testosterone below range; LH and FSH both elevated | Testes are receiving a strong signal but not responding. Primary hypogonadism. | Rule out Klinefelter syndrome; consider TRT if symptomatic and confirmed on repeat testing [6] |
| Low T, low LH, low FSH | Testosterone below range; both pituitary signals low or near-zero | Brain is not sending the signal. Secondary hypogonadism. Stress, obesity, and opioids are common causes. | Investigate pituitary; address reversible causes first [6] |
| Normal total T, high SHBG, low free T | Total testosterone in range; SHBG elevated; calculated free T below normal | Plenty of testosterone in the blood, but most of it is locked up and unavailable. Functionally low androgen activity. | Confirm with free testosterone measurement; assess for causes of elevated SHBG [3] |
| Low T, low-normal LH | Testosterone below range; LH not appropriately elevated | Pituitary response is blunted. Often seen with chronic stress, obesity, and sleep disruption. | Evaluate lifestyle factors; chronic stress suppresses LH pulsatility [6] |
The low T / low LH pattern is worth pausing on. Chronic stress and its effect on testosterone explains exactly how cortisol suppresses the pituitary signal, and [obesity's
Numbers without symptoms are context, not a diagnosis. The questions below help you and your clinician connect the two, so that any decision about treatment rests on the full picture rather than a single lab value.
Before you leave the appointment, ask:
The first 90 days on any protocol bring the most change; knowing what to expect keeps you calibrated. What to expect in your first 90 days on TRT walks through that window in detail. If you are ready to review your panel with a clinician, book a consultation and bring these questions with you.
Total testosterone is all the testosterone in your blood, both bound to proteins and unbound. Free testosterone is the small fraction that's actually unbound and biologically active, what your body can actually use. Think of it like a bank account: total testosterone is your account balance, while free testosterone is the cash in your wallet you can spend today. Most circulating testosterone is locked up by binding proteins, making only the free portion relevant to how you feel and function.
This often happens when SHBG (sex hormone-binding globulin), the protein that binds testosterone, is abnormally high or low. A high SHBG locks up testosterone, leaving little free testosterone available to your tissues even though total testosterone appears normal. Conversely, low SHBG may mean less bioavailable testosterone despite a normal total reading. Your clinician should measure free testosterone alongside SHBG to see whether your functional androgen exposure matches your symptoms.
High LH with low testosterone suggests primary hypogonadism, meaning your testes are not responding properly to your brain's signal. Your pituitary gland is sending a strong message to produce more testosterone, but the testes are struggling. This differs from secondary hypogonadism, where both LH and testosterone are low, indicating the brain never sent a strong signal in the first place. Identifying which pattern you have shapes the next diagnostic steps.
Men need some estradiol for bone health, cardiovascular function, and libido. Estradiol comes from the conversion of testosterone to estrogen, a process that happens faster when body fat is higher. If estradiol is elevated, you may notice water retention, soft fat gain around the chest, reduced morning erections, or emotional flatness. The measurement method matters: make sure your lab used a sensitive assay (LC-MS/MS), not a standard one designed for women's higher levels.
Ask whether both testosterone samples were fasting between 7 and 10 a.m., since timing affects results. If total testosterone is borderline, ask whether free testosterone was calculated using SHBG. Confirm that your symptoms match what the numbers suggest. Ask about cardiovascular risk assessment if TRT is being considered. Finally, ask when you'll retest and what specific changes you should monitor, since the first 90 days bring the most noticeable change.
Take our 2-minute hormone & metabolism quiz to see exactly where you stand — or jump straight to labs or a free screen with our team.