Testostérone | Clinique Omicron Québec

Normal values by sex and age

• Adult man (20–40 years old): Total testosterone 8–35 nmol/L (230–1010 ng/dL) + morning fasting sample between 7 a.m. and 11 a.m. (morning peak — circadian variation of 30–40 30–40 %) + calculated free testosterone: 180–550 pmol/L
• Elderly man (> 60 years old): total testosterone decreases gradually by 1–2 % per year after age 30 + + SHBG increases with age → free testosterone decreases faster than total testosterone → a 70-year-old man may have normal total testosterone but low free testosterone (androgen deficiency in aging males — ADAM)
• Adult woman: total testosterone 0.5–2.5 nmol/L (15–70 ng/dL) + about 20 times lower than in men + important concentrations for libido + well-being + muscle mass + bone density in women too
• Circadian variation morning between 6 am and 10 am + nadir in the afternoon and evening → always collect in the morning for reliable dosage

Male hypogonadism — testosterone deficiency

• Primary hypogonadism (hypergonadotropic): Testicular failure → low testosterone + high LH + high FSH + causes: Klinefelter syndrome (XXY — most common genetic cause of primary hypogonadism + gynecomastia + firm small testicles + infertility) + orchitis (mumps ++) + chemotherapy + radiotherapy + trauma + bilateral cryptorchidism + testicular torsion
• Secondary hypogonadism (hypogonadotropic) Hypothalamic-pituitary failure → low testosterone + low LH + low FSH + causes: pituitary adenoma + hyperprolactinemia (prolactinoma) + Kallmann syndrome (anosmia + GnRH deficiency) + hemochromatosis (iron deposition in the pituitary) + aging (PADAM - late-onset hypogonadism) + severe obesity (hyperestrogenism from peripheral aromatization + insulin's suppressive effect on GnRH) + prolonged corticosteroids + opioids (gonadal axis suppression)
• Symptoms of testosterone deficiency in men: Decreased libido +++ + erectile dysfunction + fatigue + decreased energy + depression + cognitive impairment + decreased muscle mass + increased fat mass (particularly abdominal) + decreased bone density + osteoporosis + normocytic anemia + decreased body hair + hot flashes + gynecomastia (if estradiol is high)
• Diagnostic Criteria (European Association of Urology 2023): total testosterone < 8–10 nmol/L (symptoms very likely) + OR total testosterone between 8 and 12 nmol/L with low free testosterone + AND compatible clinical symptoms → diagnosis always requires the combination of low testosterone AND symptoms

Testosterone Replacement Therapy (TRT)

Contraindications and monitoring of TRT

• Absolute contraindications to TRT: Prostate cancer (known or suspected) + male breast cancer + desire for paternity (exogenous testosterone suppresses spermatogenesis via negative feedback on LH/FSH → azoospermia under TRT) + severe polycythemia (Hct > 54 %) + uncontrolled heart failure + untreated severe sleep apnea
• Surveillance under TRT Total testosterone (target 12–25 nmol/L or mid-normal range) + CBC (hemoglobin + hematocrit — risk of polycythemia) + PSA (before treatment + at 3 months + then annually) + lipid panel + weight + symptoms + mood + libido + erectile function + bone density if initial osteoporosis
• Risks of TRT: polycythemia (increased hemoglobin → thrombotic risk if Hct > 54% % → reduce dose or phlebotomy) + testicular atrophy (suppression of endogenous LH) + infertility (azoospermia reversible upon cessation in 90 %% of cases after 1–2 years) + possible worsening of sleep apnea + acne + prostate enlargement (but no evidence of increased prostate cancer risk in recent randomized studies)
• hCG (human chorionic gonadotropin): Alternative to TRT for preserving fertility + stimulates endogenous Leydig cells → increased testosterone + no suppression of spermatogenesis + used if desire for paternity or if unacceptable testicular atrophy

Testosterone in women — hyperandrogenism and deficiency

• Female hyperandrogenism Elevated total testosterone + or elevated free androgen index (FAI) → severe acne + hirsutism + androgenic alopecia + menstrual irregularities + virilization → causes: PCOS (most common) + congenital adrenal hyperplasia (21-hydroxylase deficiency) + ovarian or adrenal tumor (very high testosterone > 5–6 nmol/L → diagnostic emergency) + Cushing's
• Hyperandrogenism Workup: Total testosterone + SHBG + Free Androgen Index (FAI) + DHEA-S (adrenal androgen) + 17-OHP (21-hydroxylase deficiency) + prolactin + TSH + FSH + LH + cortisol if Cushing's suspected + ovarian ultrasound
• Testosterone deficiency in women (controversial context): menopause + post-oophorectomy + adrenal insufficiency → significant reduction of testosterone → decreased libido + fatigue + reduced well-being + low-dose testosterone gel (300 µg/day) → improved libido in menopausal women (ESHRE + Endocrine Society 2019 data) + not formally approved in Canada but used in practice

Consult at Clinique Omicron

Clinique Omicron's nurse practitioners (NPs) and physicians dose and interpret total and free testosterone in the correct clinical context, diagnose male hypogonadism (primary vs. secondary—LH + FSH + prolactin + pituitary MRI if secondary), initiate and monitor TRT according to the patient's profile (gel + injection + patch), ensure monitoring (CBC + PSA + lipids + symptoms), evaluate female hyperandrogenism (PCOS + adrenal hyperplasia + tumor), and refer to endocrinology or urology for complex cases. Consultations are available at several service points in Quebec and via telemedicine. To make an appointment, visit cliniqueomicron.ca.

The content of this page is for informational purposes only and does not replace the advice of a doctor or endocrinologist. Testosterone replacement therapy is contraindicated in cases of known or suspected prostate cancer and in cases where paternity is desired without prior fertility preservation measures. Always collect testosterone in the morning between 7 AM and 11 AM for reliable measurement.