For a 51-year-old male patient with erectile dysfunction who has shown an adequate response to tadalafil, should the initial evaluation include checking only free and total testosterone levels or also assess FSH, LH, and prolactin levels?

Hormonal Testing in ED with Adequate Response to Tadalafil

For a 51-year-old patient with erectile dysfunction who is already responding adequately to tadalafil, you should check only total testosterone (and free testosterone if total is low), without routinely adding FSH, LH, or prolactin. 1

Rationale for Testosterone-Only Screening

• The American College of Physicians guideline explicitly states that the value of routine hormonal testing for ED evaluation is unclear, given insufficient evidence that men with ED have higher prevalence of hormonal abnormalities than men without ED. 1

• Serum total testosterone should be measured in all men with ED to determine if testosterone deficiency (defined as total testosterone <300 ng/dL with symptoms) is present, as this is the only hormonal test recommended by the American Urological Association for routine ED evaluation. 1

• The prevalence of low testosterone in men with ED ranges from 12.5% to 35%, making it the most clinically relevant hormonal abnormality to screen for. 1

When to Add Additional Hormonal Tests

Prolactin, FSH, and LH should only be measured selectively, not routinely:

• Check prolactin only if: testosterone is confirmed low on repeat testing (<300 ng/dL), the patient has decreased libido, gynecomastia is present on examination, or testosterone is particularly low (<4 ng/mL or <140 ng/dL). 2, 3

• Check FSH and LH only if: testosterone is confirmed low on repeat measurement to differentiate primary from secondary hypogonadism and identify potential pituitary pathology. 4, 3

• Hyperprolactinemia prevalence in ED patients is only 1.8-5%, and prolactinomas are rare (0.38%), making routine screening inefficient. 2, 3

Critical Considerations for Your Patient

Since your patient is already responding adequately to tadalafil, the clinical urgency for extensive hormonal workup is reduced:

• PDE5 inhibitors like tadalafil demonstrate 69% success rates versus 33% with placebo, and your patient falls into the responder category. 1

• However, testosterone deficiency may still be present and worth identifying because PDE5 inhibitors may be more effective when combined with testosterone therapy if hypogonadism exists. 5

• If initial total testosterone is low, measure free testosterone or calculate the androgen index, as this can prevent unnecessary further evaluation in 50% of cases with borderline total testosterone. 2

Practical Testing Algorithm

1. Measure total testosterone first (preferably morning sample, as levels vary diurnally). 1

2. If total testosterone is <300 ng/dL: Repeat the measurement to confirm, and add free testosterone or androgen index. 4, 2

3. If confirmed low testosterone with symptoms: Then add prolactin, FSH, and LH to evaluate for secondary hypogonadism or pituitary pathology. 4, 3

4. If total testosterone is normal: No further hormonal testing is needed unless specific clinical features emerge (decreased libido, gynecomastia, testicular atrophy). 3

Common Pitfalls to Avoid

• Do not rely on clinical history alone to predict hypogonadism—decreased libido and testicular atrophy cannot reliably predict low testosterone, missing 40% of cases. 2, 3

• Avoid single abnormal testosterone measurements as the basis for diagnosis—up to 40% normalize on repeat testing. 3

• Do not routinely screen prolactin in all ED patients, as this misses the cost-effectiveness threshold given low prevalence and the fact that testosterone screening will capture most clinically significant cases. 3

• Age matters: your 51-year-old patient falls into the higher-risk category where testosterone screening is particularly justified (9% prevalence of low testosterone in men ≥50 years versus 4% in younger men). 3