Male hypogonadism
Male hypogonadism is testicular failure to produce adequate testosterone and sperm, diagnosed with two low 8 AM fasting total testosterone levels plus LH and FSH to localize the defect, and treated with testosterone replacement in men not seeking fertility.
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What this article covers
- Overview
Male hypogonadism is failure of the testes to produce physiologic testosterone and a normal sperm number from disruption anywhere along the hypothalamic-pituitary-testicular axis.
- Epidemiology
Male hypogonadism appears across the age spectrum with different mechanisms at different ages.
- Risk factors
Obesity: lowers SHBG, falsely lowering total testosterone, and independently suppresses gonadotropin pulsatility.
- Pathophysiology
Primary hypogonadism reflects intrinsic testicular failure: Leydig cells cannot produce testosterone despite an adequate LH signal, so the pituitary compensates with high LH and FSH.
- Clinical features
Sexual symptoms: decreased libido, decreased spontaneous erections, and infertility with low or absent sperm count and reduced ejaculate volume.
- Differential diagnosis
Obesity-associated low SHBG: total testosterone is low, but free or bioavailable testosterone is normal, distinguishing pseudo-deficiency from true hypogonadism.
- Diagnosis
Establishing the diagnosis: male hypogonadism is confirmed by two separate low 8 AM (morning) fasting total testosterone measurements, roughly in the 264 to 300 ng/dL range or lower, in a man with…
- Management
First, determine the cause: identify primary versus secondary hypogonadism before starting therapy, since this changes the regimen and its contraindications.
- Complications
Erythrocytosis: hematocrit above 50 to 54% increases thrombotic risk and is the most common reason to hold testosterone therapy.
- Prognosis
Symptomatic benefit, including improved libido, lean muscle mass, bone density, and secondary sexual characteristics, is expected once testosterone reaches the mid-normal range, though the effect on cardiovascular outcomes remains unclear.
- Prevention
Correct reversible causes first: treat obesity, taper unnecessary chronic opioids, and manage OSA before confirming a permanent diagnosis, since these can normalize testosterone without lifelong replacement.
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