Testosterone Blood Test: Normal Ranges, Causes & What Your Results Mean

What Is Testosterone?

Testosterone is the primary male sex hormone (androgen), though it is also produced in smaller amounts by the ovaries and adrenal glands in women. In men, the testes produce approximately 95% of circulating testosterone under the control of luteinising hormone (LH) from the pituitary gland.

Testosterone drives male sexual development during puberty, maintains muscle mass, bone density, red blood cell production, libido, and sperm production throughout life. In women, testosterone contributes to libido, bone health, muscle tone, and overall vitality. Both deficiency and excess cause significant symptoms in either sex.

Most testosterone in the blood is bound to proteins: approximately 60–70% to SHBG (tightly bound, biologically inactive) and 30–40% to albumin (loosely bound, partially available). Only 1–3% circulates as free testosterone — the biologically active fraction.

Why Is Testosterone Tested?

• Male hypogonadism — low energy, reduced libido, erectile dysfunction, depression, loss of muscle mass
• Female androgen excess — hirsutism, acne, hair loss, irregular periods (PCOS investigation)
• Fertility assessment — testosterone is essential for spermatogenesis
• Monitoring testosterone replacement therapy (TRT)
• Delayed or precocious puberty
• Bone health — low testosterone contributes to osteoporosis in both sexes

Normal Ranges

Testosterone follows a circadian rhythm, peaking in the early morning. Blood should be drawn before 10 AM for accurate assessment. Two low morning results are needed before diagnosing hypogonadism (BSGE/BSSM guidelines).

What Do High Testosterone Levels Mean?

• PCOS (women) — the most common endocrine disorder in women of reproductive age
• Congenital adrenal hyperplasia — excess adrenal androgen production
• Anabolic steroid use — exogenous testosterone dramatically elevates levels
• Androgen-secreting tumours — rare ovarian or adrenal tumours
• Cushing's syndrome — cortisol excess increases adrenal androgens
• Resistance training — acute elevations after heavy exercise (transient)

What Do Low Testosterone Levels Mean?

• Primary hypogonadism — testicular failure (Klinefelter syndrome, trauma, chemotherapy, orchitis)
• Secondary hypogonadism — pituitary or hypothalamic dysfunction (tumours, haemochromatosis, Kallmann syndrome)
• Ageing — testosterone declines ~1–2% per year after age 30 (sometimes called "andropause")
• Obesity — excess adipose tissue increases aromatase activity, converting testosterone to oestradiol
• Chronic illness — diabetes, liver disease, kidney disease, HIV all lower testosterone
• Medications — opioids, corticosteroids, antiandrogens, and GnRH agonists
• Stress and sleep deprivation — cortisol suppresses the HPG axis

How to Optimise Testosterone Levels

• Resistance training — compound lifts (squats, deadlifts, bench press) acutely boost testosterone
• Maintain healthy body composition — losing excess body fat is one of the most effective ways to raise testosterone naturally
• Sleep 7–9 hours — most testosterone is produced during REM sleep; short sleep dramatically reduces levels
• Manage stress — chronic cortisol elevation suppresses testosterone production
• Adequate zinc and vitamin D — both are essential cofactors for testosterone synthesis
• Moderate alcohol — excessive alcohol directly suppresses Leydig cell function
• Consider TRT — if levels are persistently low with symptoms, discuss testosterone replacement with an endocrinologist

When Should You Get Tested?

• Men with fatigue, low libido, erectile dysfunction, or mood changes
• Women with excess hair growth, acne, or irregular periods
• Fertility investigations
• Men over 40 experiencing declining energy or muscle mass
• Before and during testosterone replacement therapy

Which Lola Health Tests Include Testosterone?

Total testosterone is included in our Hormone 7 panel alongside SHBG, oestradiol, LH, FSH, progesterone, and prolactin. Also included in Peak Insights. Available as an add-on with any blood test.