When should testosterone levels be checked in adult men?

When to Check Testosterone Levels in Adult Men

Testosterone levels should be measured in all men presenting with decreased libido, erectile dysfunction (especially when PDE5 inhibitor therapy has failed), or decreased spontaneous/morning erections, using morning total testosterone drawn between 8-10 AM on at least two separate occasions. 1, 2, 3

Primary Indications for Testing

Sexual Symptoms (Strongest Indication)

• Decreased libido is the most specific symptom warranting testosterone measurement and should always prompt evaluation 3, 4
• Erectile dysfunction, particularly in men aged 30-60 years or when sildenafil/other PDE5 inhibitors have failed, requires testosterone testing 1, 2, 3
• Decreased spontaneous or morning erections are more specific for hypogonadism than other symptoms 3
• Among men seeking consultation for sexual dysfunction, approximately 36% have hypogonadism 1

Physical Findings and Objective Signs

• Testicular atrophy on physical examination justifies testing 3, 5
• Reduced bone mineral density or low-trauma fractures warrant evaluation 3
• Decreased muscle mass with increased adiposity may support testing when combined with sexual symptoms 2, 6

Special Populations Requiring Testing

• Men with diabetes who have symptoms or signs of low testosterone should have morning total testosterone measured using an accurate assay 2, 3
• Men with metabolic syndrome or obesity presenting with sexual dysfunction 2

What NOT to Test For

The American College of Physicians specifically recommends against testing testosterone to evaluate isolated complaints of fatigue, decreased energy, poor physical function, or cognitive decline. 1, 3

Critical caveats to avoid inappropriate testing:

• Age alone is not an indication—do not test asymptomatic older men simply because they are elderly 3
• Nonspecific symptoms like fatigue, decreased motivation, or mild depression alone do not justify testing 3, 4
• Approximately 20-50% of men over 60-80 years have low testosterone levels, but this does not warrant testing without specific symptoms 1, 3
• Symptoms commonly attributed to testosterone deficiency (fatigue, depression, erectile dysfunction without decreased libido) were not associated with low testosterone levels in a study of nearly 3,000 men 4

Proper Testing Protocol

Initial Testing

• Measure morning total testosterone between 8 AM and 10 AM 2, 3, 7
• Confirm diagnosis by measuring testosterone on at least two separate mornings before initiating treatment 7
• Free testosterone by equilibrium dialysis and sex hormone-binding globulin should also be measured, especially in men with obesity 2, 3

Follow-up Testing if Initial Results Are Low

• If testosterone levels are subnormal, repeat measurement and add serum LH and FSH to distinguish primary (testicular) from secondary (pituitary-hypothalamic) hypogonadism 2
• Elevated LH/FSH with low testosterone indicates primary hypogonadism 2
• Low or low-normal LH/FSH with low testosterone indicates secondary hypogonadism 2

Common Pitfalls to Avoid

• History of decreased libido or testicular atrophy cannot reliably predict hypogonadism, but their presence still warrants testing 5
• Do not attempt to diagnose type of hypogonadism (primary vs. secondary) while patient is on testosterone therapy—results will be misleading 2
• Do not assume all men on testosterone therapy actually met diagnostic criteria initially—up to 20-30% of men receiving testosterone in the US do not have documented low testosterone levels before treatment 2
• Never diagnose hypogonadism based on symptoms alone without biochemical confirmation 2, 3
• Do not use screening questionnaires alone to diagnose hypogonadism due to lack of specificity 2

Clinical Context: Why This Matters

The distinction between appropriate and inappropriate testing is critical because testosterone therapy provides small but significant improvements only in sexual function (standardized mean difference 0.35) but produces little to no effect on physical functioning, energy, vitality, or cognition even in confirmed hypogonadism 1, 2. Testing should therefore be reserved for men with specific sexual symptoms where treatment has proven benefit, not for vague complaints where evidence shows no meaningful improvement.