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Patient Education · Endocrinology
Male Hypogonadism & Testosterone Deficiency
A guide to understanding low testosterone in men — its causes, symptoms, diagnosis, and treatment options.
If you have questions about testosterone or male hormonal health, please contact our office. All care is individualized.
Understanding Testosterone
What is testosterone and why does it matter?
Testosterone is the principal male sex hormone, essential for sexual function, muscle mass, bone density, red blood cell production, energy, mood, and cognitive function. Levels peak in early adulthood and decline gradually with age — approximately 1–2% per year after age 30. Hypogonadism refers to testosterone deficiency that is clinically significant.
How prevalent is low testosterone?
By age 60, approximately 20% of men have frankly low total testosterone. The prevalence rises to ~30% by age 70 and ~50% by age 80.
Free testosterone — the fraction available to tissues — is often more clinically meaningful than total testosterone, particularly in older men with elevated SHBG. Many men with symptoms have “low-normal” total testosterone but significantly reduced free testosterone.
Symptoms
What are the symptoms of low testosterone?
Sexual: Reduced libido (the most consistent symptom), erectile dysfunction, reduced morning erections, infertility.
Physical: Decreased muscle mass and strength, increased body fat (particularly abdominal), reduced bone density, fatigue.
Cognitive and mood: Low mood or depression, reduced motivation, difficulty concentrating, reduced sense of well-being.
These symptoms overlap with many other conditions — thyroid disease, sleep apnea, depression, anemia. We evaluate systematically to ensure the diagnosis is accurate before initiating treatment.
Diagnosis
How is low testosterone diagnosed?
Testosterone must be measured in a morning blood sample — levels peak in the early morning and fall 25–50% through the day. We measure: Total testosterone, Free testosterone, LH and FSH, and Prolactin.
The diagnosis requires at least two low morning testosterone levels combined with symptoms. A single low value is not sufficient.
Are there secondary causes of low testosterone to rule out?
Obesity: Adipose tissue converts testosterone to estrogen and suppresses the pituitary-gonadal axis. Weight loss can significantly improve levels.
Obstructive sleep apnea: One of the most underrecognized suppressors of testosterone. Treatment of OSA often improves testosterone without medication.
Medications: Opioids, glucocorticoids, anabolic steroids, and certain antidepressants suppress testosterone.
Treatment
What are the options for testosterone replacement?
Transdermal Gels AndroGel · Testim · Fortesta
Applied daily to the skin. Convenient and easy to adjust. Risk of inadvertent transfer to female partners or children — requires care.
Intramuscular Injections Testosterone Cypionate · Enanthate
Injected weekly or biweekly. Inexpensive and effective. Causes peaks after injection and troughs before the next dose. We often teach self-injection.
Subcutaneous Pellets Testopel
Implanted every 3–6 months. Convenient but levels cannot be adjusted once placed.
Oral Testosterone Undecanoate · Jatenzo
Taken with food twice daily. Avoids liver toxicity of older oral androgens.
Does testosterone replacement affect fertility?
Yes — and this is frequently underappreciated. When testosterone is administered externally, the pituitary stops signaling the testes, which then stop producing sperm. Azoospermia is common. Recovery can take 6–18 months and is not guaranteed.
For men who wish to preserve fertility: HCG maintains testicular production and spermatogenesis. Clomiphene citrate raises endogenous testosterone without external replacement. We discuss fertility goals explicitly before initiating any therapy.
What monitoring is required on testosterone therapy?
We check: Testosterone levels (to confirm therapeutic levels), Hematocrit (testosterone stimulates red blood cells — elevated levels increase clotting risk), and PSA (before initiation and periodically thereafter). We schedule follow-up at 3 months initially, then every 6–12 months once stable.