Testosterone —
what your level
actually means.
A testosterone result without context is almost meaningless. Age, time of draw, SHBG levels, and symptoms all determine whether your number is clinically significant. Here's how to read your result properly.
Dr. Emma Walsh, MD, MPH
Preventive Medicine, Thyroid Disorders ·
The essentials — before you read the full guide below.
Total vs free testosterone
Total testosterone includes all circulating testosterone — bound to SHBG, albumin, or free. Only free testosterone (about 2–3%) is biologically active. Symptoms can occur with low free T even when total T is normal.
Normal ranges vary widely
Men: 10–35 nmol/L (288–1008 ng/dL). Women: 0.5–2.6 nmol/L (14–75 ng/dL). Ranges differ by lab, age, and time of day — always use your report's reference range.
Draw in the morning
Testosterone peaks in early morning (7–10 AM) and falls by 25–35% through the day. An afternoon draw can be falsely low — confirmatory testing should always be in the morning.
Symptoms matter most
Low testosterone is a clinical diagnosis, not a number alone. Fatigue, reduced libido, erectile dysfunction, and mood changes alongside a low morning total testosterone are required for hypogonadism diagnosis.
Reference Ranges
What does your number
actually mean?
Use the interactive slider below, or read the range cards for a full clinical breakdown.
Testosterone (Total & Free) Reference Ranges
nmol/L (Total T)Enter your result
Drag to see what your Testosterone (Total & Free) means
The Science
Why SHBG changes everything about your testosterone result
Most testosterone in the blood is bound — primarily to sex hormone-binding globulin (SHBG) and albumin. Only free (unbound) testosterone enters cells and has biological effect. When SHBG is elevated (common with ageing, oestrogen, thyroid disease), total testosterone may appear normal while free testosterone is actually low. This is why free testosterone or calculated free testosterone is often more clinically meaningful than the total.
LH and FSH distinguish primary from secondary hypogonadism
Primary hypogonadism (testicular failure) shows low testosterone with high LH and FSH — the pituitary is signalling loudly to damaged testes. Secondary hypogonadism (pituitary/hypothalamic cause) shows low testosterone with low or normal LH/FSH — the signal itself is absent.
SHBG rises with ageing and obesity
SHBG increases with age, oestrogen, and thyroid disease, binding more testosterone and reducing free levels. Obesity typically lowers SHBG, meaning obese men may have low total testosterone but near-normal free testosterone — a pattern that can confuse interpretation.
Testosterone declines naturally with age
Total testosterone declines approximately 1–2% per year after age 30–40 — a gradual process sometimes called late-onset hypogonadism or 'andropause'. Symptoms only develop when the decline is more substantial, typically below 10–12 nmol/L.
When to Test
Signs your doctor will
order this test
These are the most common reasons a Testosterone (Total & Free) test is requested — from symptoms to routine screening.
Fatigue and reduced motivation (men)
Fatigue with reduced libido and loss of morning erections forms the classic triad of male hypogonadism. All three symptoms plus a confirmed low morning testosterone are required for diagnosis.
Classic triadUnexplained weight gain or muscle loss
Testosterone promotes muscle protein synthesis and inhibits fat storage. Low T causes a shift toward central adiposity and muscle wasting — often misattributed to poor diet or ageing.
Metabolic effectIn women: acne, hirsutism, irregular periods
Elevated testosterone in women causes acne, excess facial/body hair, and menstrual irregularity. PCOS is the most common cause. Ovarian or adrenal testosterone-secreting tumours are rare.
Women: androgen excessOsteoporosis (men)
Testosterone is essential for bone density in men. Hypogonadism is an important and under-recognised cause of osteoporosis in men — often discovered incidentally on DEXA scan.
Bone healthInfertility investigation
Testosterone is part of male infertility workup alongside FSH, LH, and semen analysis. Abnormal testosterone can reduce sperm production.
Infertility screenMonitoring TRT or anti-androgen therapy
Testosterone replacement therapy (TRT) requires regular monitoring of total T, haematocrit (polycythaemia risk), and PSA. Anti-androgens in prostate cancer require low testosterone confirmation.
Treatment monitoringTesting Schedule
How often should
you get tested?
Frequency depends on your current health status and your doctor's guidance.
Always morning for diagnosis
Testosterone peaks early morning. Diagnostic measurement must be a morning draw — afternoon values can be 25–35% lower, leading to false diagnosis of hypogonadism.
Confirm on a second draw
A single low testosterone should always be confirmed with a second morning draw 4–6 weeks later before making a diagnosis of hypogonadism.
During testosterone therapy
Total T, haematocrit, PSA, and LFTs are monitored every 3–6 months during testosterone replacement therapy.
Symptomatic men over 40
Annual testosterone is reasonable for men over 40 with fatigue, reduced libido, or mood changes that might reflect declining levels.
If Your Result Is Abnormal
What to do next with a low or high testosterone result
Testosterone results require clinical context — a number alone is never enough to act on.
Low total T → add LH, FSH, SHBG, prolactin
LH and FSH distinguish primary (testicular) from secondary (pituitary) hypogonadism. SHBG and calculated free T determine true androgen status. Prolactin excludes hyperprolactinaemia as a cause.
LH + FSH + SHBG + prolactinConfirm with a second morning draw
Never treat based on a single result. A second morning total testosterone 4–6 weeks later confirms true hypogonadism. Ensure the patient is well, not acutely unwell, at time of draw.
2nd morning draw 4–6 weeks laterHigh testosterone in women → PCOS workup
Elevated testosterone in women warrants pelvic ultrasound, LH:FSH ratio, DHEA-S, and fasting glucose/insulin ratio to investigate PCOS and exclude adrenal causes.
PCOS + adrenal screenConfirmed hypogonadism → endocrinology
Confirmed symptomatic hypogonadism requires endocrinology assessment before starting TRT — to establish cause, assess fertility goals, and exclude pituitary pathology (MRI if LH/FSH low).
Endocrinology + pituitary MRI if needed