Reading your testosterone lab results without clinical context leads to two common errors: dismissing a low result because it falls inside the reference range, or panicking over a number that looks low but is physiologically normal for your age and symptoms. This guide walks through each marker on a testosterone panel and what your clinician should be reading into it.
- Total testosterone is the least actionable marker alone — free testosterone and SHBG determine what your tissues can actually use.
- A total testosterone of 350 ng/dL can be "in range" (264-916 ng/dL) yet functionally low depending on age and symptoms.
- High SHBG binds more testosterone, so two men with identical total testosterone can have very different free testosterone.
- LH and FSH identify whether low testosterone originates in the testes (primary) or the pituitary (secondary).
- Estradiol should be monitored alongside testosterone — both too high and too low levels cause symptoms.
- After starting therapy, recheck labs at 6-8 weeks, not 3 months, to confirm dose and monitor estradiol.
TL;DR
A complete testosterone panel in 2026 includes total testosterone, free testosterone, SHBG (sex hormone-binding globulin), and sometimes albumin and LH. The reference range on the lab report is statistical, not clinical — a total testosterone of 350 ng/dL is technically "normal" but may be suboptimal for a 40-year-old man with fatigue, low libido, and reduced muscle mass. GoodLife Health clinicians read testosterone labs alongside symptoms, not in isolation, and a treatment protocol is built from the relationship between free testosterone, SHBG, and your clinical picture.
The number on the page is the start of the conversation, not the end of it — free testosterone and SHBG often tell a different story than total testosterone alone.
Why this matters
Testosterone declines with age at roughly 1-2% per year after age 30, but the rate varies significantly between individuals. By age 45, many men have total testosterone levels that technically fall inside the lab's reference range (typically 264-916 ng/dL for adult males) but are functionally low for their body composition, energy, and libido.
The critical gap: most lab reports show total testosterone and call it a day. But bioavailable testosterone — the fraction your tissues can actually use — depends on SHBG. High SHBG binds more testosterone, leaving less free testosterone available to tissues. Two men with identical total testosterone of 500 ng/dL can have dramatically different free testosterone if one has SHBG of 25 nmol/L and the other has 60 nmol/L.
This is why best labs to run before starting hormone therapy includes SHBG, not just total testosterone. If your clinician only ordered total testosterone, you're missing the marker that determines whether the testosterone you have is actually usable.
What you'll need
- Your lab results showing total testosterone, free testosterone, and SHBG (if your panel didn't include all three, ask your clinician to add the missing ones)
- The reference ranges from your specific lab (ranges vary by lab and method)
- A list of symptoms you're experiencing: fatigue, low libido, reduced muscle mass, difficulty concentrating, mood changes, sleep disturbances
- Your age, body weight, and any medications that affect testosterone (opioids, statins, corticosteroids, SSRIs)
- Recent labs for LH, FSH, and estradiol if available — these complete the picture
The steps
1. Read total testosterone in context, not in isolation
Total testosterone is the headline number, but it's the least actionable marker alone. The lab reference range for adult males typically spans 264-916 ng/dL, which is wide enough to include both symptomatic deficiency and optimal function. A total testosterone of 350 ng/dL in a 25-year-old is concerning; the same value in a 70-year-old may be age-appropriate. GoodLife Health clinicians evaluate total testosterone against age-adjusted expectations and symptom presentation, not just the lab's reference range. Common mistake: seeing your total testosterone is "in range" and concluding your testosterone is fine — the bottom of the range is not the same as optimal.
2. Check free testosterone — the fraction your body actually uses
Free testosterone is the unbound, biologically active fraction — typically 2-3% of total testosterone. It's the portion available to bind to androgen receptors in muscle, brain, and other tissues. A low free testosterone with a normal total testosterone usually means SHBG is elevated, binding up most of the hormone. This pattern is common in men with insulin resistance, hypothyroidism, or aging-related SHBG increase. If your lab report shows free testosterone below the reference range (typically below 50-65 pg/mL depending on the lab), that's a stronger clinical signal than total testosterone alone. Common mistake: ignoring free testosterone because total testosterone looks fine — free testosterone is the number that correlates with symptoms.
3. Interpret SHBG — the binding protein that determines bioavailability
SHBG is the protein that binds testosterone in the bloodstream. When SHBG is high, more testosterone is bound and less is free. SHBG increases with age, liver conditions, hyperthyroidism, and certain medications. It decreases with obesity, insulin resistance, and hypothyroidism. A high SHBG with normal total testosterone means your body isn't getting enough of the hormone to tissues — even though the total looks adequate. A low SHBG can indicate insulin resistance, which means your body may be producing testosterone but also dealing with a metabolic problem that suppresses production over time. How doctors diagnose insulin resistance covers the metabolic side of this equation. Common mistake: not having SHBG tested at all — without it, you can't calculate bioavailable testosterone or understand why total and free testosterone may disagree.
What each marker tells your clinician
| Marker | What it measures | Why it matters |
|---|---|---|
| Total testosterone | All testosterone in the bloodstream, bound and unbound | Headline number, but wide reference range (264-916 ng/dL) makes it the least actionable alone |
| Free testosterone | Unbound, active fraction (~2-3% of total) | Correlates most strongly with symptoms; low free testosterone can occur even with normal total |
| SHBG | Protein that binds testosterone | High SHBG leaves less free testosterone; determines bioavailability |
| LH / FSH | Pituitary signaling hormones | High LH/FSH with low testosterone points to primary hypogonadism; low/normal LH points to secondary |
| Estradiol | Testosterone's aromatized conversion product | Too high or too low both cause symptoms and require monitoring |
4. Look at LH and FSH to understand the cause
LH (luteinizing hormone) and FSH (follicle-stimulating hormone) tell you whether the problem is in the testes (primary hypogonadism) or in the pituitary (secondary hypogonadism). High LH and FSH with low testosterone means the testes aren't producing enough — the pituitary is trying to stimulate them but they're not responding. Low or normal LH with low testosterone means the pituitary isn't sending enough signal — this is secondary hypogonadism, and the cause may be in the brain (stress, pituitary issues, medications, or obesity). Your clinician should always check LH and FSH alongside testosterone to determine the cause before starting treatment. Testosterone and muscle mass: how therapy changes body composition covers what happens after treatment starts, but the cause matters for how treatment is structured. Common mistake: starting testosterone therapy without knowing whether the deficiency is primary or secondary — the cause can change the treatment approach and monitoring requirements.
5. Check estradiol — testosterone converts to estrogen
Testosterone aromatizes (converts) to estradiol in men, and this is normal and necessary for bone health, libido, and cardiovascular function. But if estradiol is too high — common in men with higher body fat — it can cause gynecomastia, water retention, and mood changes. If estradiol is too low (common in men on testosterone therapy who over-suppress aromatization), it can cause joint pain, low libido, and cardiovascular issues. Your clinician should check estradiol alongside testosterone, especially if you're already on therapy. Common mistake: ignoring estradiol because it's a "female hormone" — estradiol is clinically important in men, and testosterone therapy without estradiol monitoring is incomplete care.
A high SHBG with normal total testosterone means your body isn't getting enough of the hormone to tissues — even though the total looks adequate. A low SHBG can indicate insulin resistance, which means your body may be producing testosterone but also dealing with a metabolic problem that suppresses production over time.
6. Review the labs with your clinician, not the portal
A portal notification that says "testosterone: 380 ng/dL, normal" tells you nothing useful. Your clinician should walk through total testosterone, free testosterone, SHBG, LH, FSH, and estradiol together and explain what the pattern means. A clinician who only prescribes based on total testosterone is reading a fraction of the panel. How to know if you need hormone replacement therapy covers the decision framework, but the lab reading is the foundation. Common mistake: accepting a portal message that says "your labs are normal" without a clinical conversation — normal on a lab report and optimal for your symptoms are different standards.
7. Recheck labs at the right interval
If you start testosterone therapy, recheck total testosterone, free testosterone, SHBG, and estradiol at 6-8 weeks, not at 3 months. The initial recheck confirms whether the dose is bringing testosterone into the target range and whether estradiol is staying in check. If labs are rechecked too early (under 4 weeks), the levels haven't stabilized. If too late (over 12 weeks), you've gone three months without knowing whether the protocol is working. Common mistake: waiting 6 months for the first recheck — by then, side effects from an wrong dose may have been present for months.
Troubleshooting
Your total testosterone is normal but you have low-T symptoms. Check free testosterone and SHBG. If SHBG is high and free testosterone is low, you have functional hypogonadism despite a normal total — this is a legitimate clinical finding that warrants treatment.
Your testosterone is low but your clinician won't prescribe. Ask whether they've checked LH, FSH, and estradiol. If they haven't, the workup is incomplete — a clinician who prescribes testosterone without understanding the cause is practicing prescription medicine, not hormone optimization.
Your testosterone improved on therapy but symptoms didn't. Check estradiol — if it's too high, it can cause symptoms that mimic low testosterone (fatigue, low libido, mood changes). Also check thyroid function — hypothyroidism can cause identical symptoms and testosterone therapy won't fix them.
Your SHBG is very high and won't come down. High SHBG can be driven by liver conditions, hyperthyroidism, or aging. If SHBG stays elevated, your clinician may need to adjust the testosterone dose to achieve adequate free testosterone despite higher binding.
You're on testosterone therapy and your hematocrit is elevated. Testosterone increases red blood cell production, and elevated hematocrit (above 52-54%) increases blood viscosity. Your clinician should monitor hematocrit every 6-12 months on therapy. If it's high, dose adjustment or periodic phlebotomy may be needed.
Tools and resources
- Your complete testosterone panel: total testosterone, free testosterone, SHBG, LH, FSH, estradiol
- A symptom log tracking energy, libido, mood, sleep, and body composition changes
- Best labs to run before starting hormone therapy — the full pre-treatment panel
- How to know if you need hormone replacement therapy — the decision framework
What to do next
If your labs show low free testosterone or a pattern of functional hypogonadism, the next step is a clinical consultation — not self-treatment. Read about how to prepare for a telehealth hormone consultation so you arrive with the right questions.
FAQ
What is a normal testosterone level for a man? The lab reference range for total testosterone typically spans 264-916 ng/dL, but "normal" and "optimal" are different. A level at the bottom of the range may be technically normal but functionally low for your age and symptoms. Free testosterone is the more clinically relevant number.
What's the difference between total and free testosterone? Total testosterone includes all testosterone in the bloodstream — bound and unbound. Free testosterone is the unbound, active fraction (~2-3% of total). Free testosterone is what your tissues can actually use, and it's the number that correlates most strongly with symptoms.
What is SHBG and why does it matter? SHBG (sex hormone-binding globulin) is a protein that binds testosterone. High SHBG means more testosterone is bound and less is free. Two men with the same total testosterone can have very different free testosterone depending on SHBG levels.
Should I be worried if my testosterone is at the low end of the range? If you have symptoms of low testosterone (fatigue, low libido, reduced muscle mass, mood changes), a level at the low end of the range warrants further evaluation — especially free testosterone and SHBG. The reference range is statistical, not clinical.
How often should testosterone labs be checked? Before starting therapy: a full panel including total testosterone, free testosterone, SHBG, LH, FSH, and estradiol. On therapy: recheck at 6-8 weeks to confirm the dose is hitting target, then every 6-12 months. Off therapy: annually if you have risk factors.
Can you have low testosterone symptoms with normal lab results? Yes — if SHBG is high, free testosterone can be low even when total testosterone appears normal. This is called functional hypogonadism and is a legitimate clinical finding that warrants treatment if symptoms are present.
Does testosterone therapy affect estrogen levels? Yes — testosterone converts (aromatizes) to estradiol in men. High estradiol can cause gynecomastia and water retention; low estradiol can cause joint pain and low libido. Your clinician should monitor estradiol alongside testosterone.
One last thing
The single most common mistake in testosterone lab interpretation is treating total testosterone as the whole story. It's the headline, not the conclusion. Free testosterone tells you what's available to tissues; SHBG tells you why; LH and FSH tell you where the problem originates; estradiol tells you what the testosterone is converting into. A clinician who reads all five together is practicing hormone medicine; one who reads only total testosterone is reading a fraction of the panel and calling it a diagnosis.
Related guides
References
- Testosterone Therapy in Men with Hypogonadism: An Endocrine Society Clinical Practice Guideline. 2018. doi.org/10.1210/jc.2018-00229