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Testosterone

Fertility profile Biomarker

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Collection Type: Blood

Body System

Related System: Fertility profile

Overview

Testosterone is the primary androgen (male sex hormone) produced mainly by the testes in men and by the ovaries and adrenal glands in women. The blood test typically measures total testosterone (bound unbound) to assess androgen status. It is ordered when evaluating infertility, low libido, erectile dysfunction, delayed or precocious puberty, irregular menses, hirsutism/virilization in women, or suspected endocrine tumors. Levels vary by sex, age (peak in young adult men, gradual decline with age), time of day (highest in the early morning), and physiologic states (pregnancy, menstrual cycle). Body weight, medications, and illnesses that change SHBG will alter total testosterone measurements.

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Test Preparation

Fasting may be required in some labs

Why Do I Need This Test

Included in: Fertility profile - Symptoms prompting test: low libido, erectile dysfunction, infertility, irregular periods, excessive hair growth, unexplained weight/muscle changes, delayed/early puberty - Diagnoses/monitoring: male hypogonadism, female hyperandrogenism/PCOS, androgen-secreting tumors, response to testosterone therapy - Causes of abnormal levels: testicular/ovarian/adrenal disease, pituitary disorders, obesity, chronic illness, exogenous androgens, certain drugs - Biological meaning: low levels suggest hypogonadism or impaired androgen production; high levels indicate androgen excess - Lifestyle/family history: anabolic steroid use, obesity, alcohol, family history of early puberty, infertility, or endocrine tumors

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Understanding Test Results

In adult males, total testosterone <300 ng/dL typically indicates low testosterone (hypogonadism) and warrants clinical correlation and repeat morning measurement; values <200 ng/dL are more likely to be clinically significant and often require treatment.
Levels 300–400 ng/dL may be borderline and assessed with symptoms, free testosterone, and LH/FSH.
Levels >1000 ng/dL suggest exogenous testosterone use or a testosterone‑secreting tumor and need urgent evaluation.
In adult females, values above the upper normal (typically >70–80 ng/dL) suggest androgen excess (PCOS, ovarian/adrenal tumor); very high levels (>200 ng/dL) strongly raise concern for an androgen‑secreting neoplasm.
Low female values are usually of limited clinical consequence but should be interpreted with symptoms and other hormone tests.
SHBG, time of day, illness, and medications can shift total testosterone, so borderline or unexpected results often require repeat testing and assessment of free testosterone and pituitary function.

Normal Range

Adult males: 300-1000 ng/dL OR 10.4-34.7 nmol/L Adult females (premenopausal): 15-70 ng/dL OR 0.52-2.43 nmol/L

FAQs

Q: What does testosterone do to a man?

A: Testosterone regulates male sexual development and function. It drives puberty changes such as voice deepening and facial and body hair, and supports libido, erections and sperm production. It increases muscle mass and strength, maintains bone density, affects fat distribution, energy, mood, motivation and cognition, and helps sustain red blood cell levels. Abnormally low or high testosterone can harm fertility, mood and overall health.

Q: What happens if testosterone is low?

A: If testosterone is low, men may experience reduced sex drive, erectile difficulties, fewer spontaneous erections, low energy, depressed mood, and difficulty concentrating. Physical changes include decreased muscle mass and strength, increased body fat, loss of bone density (higher fracture risk), reduced facial/body hair, and infertility from low sperm production. Low testosterone can also contribute to anemia and metabolic changes such as insulin resistance.

Q: How can I gain my testosterone?

A: To raise testosterone, do regular resistance and high‑intensity exercise, lose excess weight, eat a balanced diet with adequate protein, healthy fats, vitamin D and zinc, limit alcohol, quit smoking, manage stress and get 7–9 hours’ sleep. Check levels with your doctor to evaluate underlying causes and discuss treatment options if needed.

Q: What happens if testosterone is high?

A: High testosterone can cause acne, oily skin, increased muscle mass, hair loss (male-pattern), and higher libido. Men may develop aggression, mood swings, sleep apnea, prostate enlargement risk and increased red blood cell count; women can get irregular periods, excess facial/body hair, voice deepening and infertility. Chronic excess—often from supplements or tumors—raises risks of cardiovascular problems, liver issues and blood clots.

Q: Which foods increase testosterone?

A: Foods that support testosterone include zinc-rich choices (oysters, beef, shellfish, pumpkin seeds), vitamin D and omega‑3 sources (fatty fish like salmon and tuna, eggs, fortified dairy), healthy fats (olive oil, avocados, nuts), and magnesium-rich greens and seeds (spinach, almonds). Legumes and cruciferous vegetables (broccoli) can help hormone balance. Maintain a balanced, calorie-appropriate diet and limit processed sugars for best results.

Q: Does testosterone increase the size of pennis?

A: Testosterone stimulates penile growth during puberty; adequate levels are required for normal development. In adult men, testosterone replacement can restore size lost from long-term deficiency, but it does not enlarge a normal adult penis beyond typical size. Exogenous testosterone in men with normal levels won’t increase girth or length; surgical or mechanical methods are the only effective ways to change adult penile size.