Testosterone (Total & Free)

What is Testosterone?

Testosterone is the primary male sex hormone (androgen) produced mainly by the testes in men and in smaller amounts by the ovaries and adrenal glands in women. It's essential for reproductive and metabolic health in both sexes.

Why is it Important?

In men, testosterone is crucial for:

• Sperm production and sexual function
• Muscle mass and strength
• Bone density
• Red blood cell production
• Mood and energy levels

In women, testosterone supports:

• Bone health and muscle strength
• Sexual desire and function
• Energy and mood
• Ovarian function

Normal Ranges by Gender

Men

Type	Range	Unit
Total Testosterone	300 – 1000	ng/dL
Free Testosterone	5.0 – 21	pg/mL
Free Testosterone (% of total)	1.5 – 4.0	%

Women

Type	Range	Unit
Total Testosterone	15 – 70	ng/dL
Free Testosterone	0.3 – 1.9	pg/mL

What Do Abnormal Results Mean?

Low Testosterone in Men (Hypogonadism)

Common causes include:

• Primary hypogonadism (testicular failure)
• Secondary hypogonadism (pituitary/hypothalamic disorders)
• Aging (gradual decline after age 30)
• Obesity
• Type 2 diabetes
• Medications (opioids, steroids)
• Klinefelter syndrome
• Chronic illness or stress

Symptoms: Low libido, erectile dysfunction, fatigue, reduced muscle mass, depression, difficulty concentrating.

High Testosterone in Men

Less common, but can indicate:

• Anabolic steroid use
• Testicular or adrenal tumors
• Congenital adrenal hyperplasia

High Testosterone in Women (Hyperandrogenism)

Common causes include:

• Polycystic ovary syndrome (PCOS)
• Congenital adrenal hyperplasia
• Ovarian or adrenal tumors
• Cushing's syndrome
• Anabolic steroid use

Symptoms: Irregular periods, acne, excess facial/body hair (hirsutism), male-pattern baldness, deepening voice.

Low Testosterone in Women

Less clinically significant, but can cause:

• Reduced libido
• Fatigue
• Loss of muscle mass
• Weak bones

Total vs Free Testosterone

• Total testosterone: All testosterone in blood (bound + unbound)
• Free testosterone: Biologically active, unbound testosterone (~2-3% of total)
• Bioavailable testosterone: Free + albumin-bound (~40-50% of total)

If total testosterone is borderline, free testosterone is more accurate.

When Should You Get Tested?

Testosterone testing may be ordered if you have:

• Sexual dysfunction or low libido
• Infertility
• Erectile dysfunction (men)
• Irregular periods or excess body hair (women)
• Unexplained fatigue or muscle weakness
• Suspected PCOS or hypogonadism
• Monitoring testosterone replacement therapy

Best testing time: Morning (7-10 AM) when levels are highest, especially for men.