Do you test Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH) in males?

Testing LH and FSH in Males

Yes, LH and FSH should be measured in males when testosterone levels are confirmed to be low on repeat testing, as these tests are essential to distinguish between primary (testicular) and secondary (hypothalamic-pituitary) hypogonadism, which fundamentally determines treatment approach and fertility potential.

When to Order LH and FSH

Initial Testosterone Assessment Required First

• Measure morning total testosterone (between 8-10 AM) on at least two separate occasions before ordering LH/FSH 1
• If total testosterone is borderline or low-normal in obese patients, also measure free testosterone by equilibrium dialysis and sex hormone-binding globulin 1
• LH/FSH testing should only proceed if testosterone levels are confirmed subnormal on repeat testing 1

Specific Clinical Scenarios Requiring LH/FSH Testing

Confirmed hypogonadism workup:

• When repeat morning testosterone levels are below the normal range (typically <300 ng/dL) 1
• LH and FSH distinguish primary testicular failure (elevated gonadotropins) from secondary hypothalamic-pituitary dysfunction (low or inappropriately normal gonadotropins) 1, 2

Symptomatic patients with specific presentations:

• Men with symptoms of hypogonadism (decreased libido, erectile dysfunction, decreased energy, reduced muscle mass, hot flashes, gynecomastia, infertility) AND low testosterone 1
• Men with diabetes who have symptoms suggestive of hypogonadism (fatigue, weight loss, decreased sexual desire, erectile dysfunction, depressive symptoms, or reduced bone mineral density) 1
• HIV-infected men with symptoms of hypogonadism and confirmed low testosterone 1

Interpretation Algorithm

Primary Hypogonadism Pattern

• Low testosterone + Elevated LH/FSH (above normal range) 2, 3
• Indicates testicular failure (cryptorchidism, bilateral torsion, orchitis, Klinefelter's syndrome, chemotherapy, toxic damage) 2
• Treatment: Testosterone replacement therapy only; fertility cannot be restored 1, 2

Secondary Hypogonadism Pattern

• Low testosterone + Low or inappropriately normal LH/FSH 1, 2
• Indicates hypothalamic-pituitary dysfunction 2
• Requires further evaluation: measure serum prolactin, iron saturation, consider pituitary function testing and MRI of sella turcica 1
• Treatment options: Testosterone replacement OR gonadotropin therapy (hCG with or without FSH) if fertility desired 1, 3

Critical Distinction for Treatment Planning

The LH/FSH results fundamentally alter management:

• Secondary hypogonadism patients can potentially achieve both fertility restoration and normal testosterone with gonadotropin therapy 1, 3
• Primary hypogonadism patients can only receive testosterone replacement, which will suppress the hypothalamic-pituitary-gonadal axis and compromise any remaining fertility 1, 2

Common Pitfalls to Avoid

Timing errors:

• Never measure LH/FSH during acute illness, as results will be unreliable 1
• Always confirm low testosterone on at least two separate morning measurements before proceeding to gonadotropin testing 1

Obesity confounding:

• In obese men with low total testosterone due solely to low sex hormone-binding globulin, free testosterone may be normal 1
• Measure free testosterone by equilibrium dialysis in obese patients before ordering LH/FSH 1

Fertility considerations:

• Always assess fertility desires before initiating testosterone replacement, as it will suppress LH/FSH and impair spermatogenesis 1, 2
• If fertility is desired and secondary hypogonadism is confirmed, gonadotropin therapy (not testosterone) should be considered 1, 3