What laboratory tests should be ordered for a 39-year-old male patient presenting with erectile dysfunction?

Laboratory Testing for Erectile Dysfunction in a 39-Year-Old Male

Order morning serum total testosterone, fasting glucose or HbA1c, and a fasting lipid profile as your core laboratory workup for this patient. 1

Essential Laboratory Tests

Morning Serum Total Testosterone (Mandatory)

• This is the only test with a specific moderate-strength recommendation from the American Urological Association for all men with ED. 1
• Must be drawn in the morning to capture peak physiologic levels 2, 3
• Testosterone deficiency is defined as total testosterone <300 ng/dL with accompanying symptoms 1
• Low testosterone may be the primary cause of ED or a contributing factor that requires separate hormone replacement therapy 2

Fasting Glucose or HbA1c (Critical for Risk Assessment)

• Diabetes is a major cause of ED and may present with erectile dysfunction as the first symptom in younger men 2, 3
• Uncontrolled diabetes significantly reduces response to first-line ED treatments 2
• Identifies a reversible/modifiable risk factor that requires immediate intervention 4, 5

Fasting Lipid Profile (Essential for Cardiovascular Risk)

• ED is a risk marker for underlying cardiovascular disease, not just a symptom. 1
• The Princeton Consensus Conference identified ED as a substantial independent predictor of future cardiac events 2
• At age 39, identifying dyslipidemia allows early intervention to prevent cardiovascular morbidity and mortality 2, 3
• ED and cardiovascular disease share common pathophysiologic pathways (endothelial dysfunction) 3, 4

Clinical Reasoning Behind This Approach

The AUA guideline explicitly states: "With the possible exception of glucose/hemoglobin A1c and serum lipids, no routine serum study is likely to alter ED management." 1 This means these three tests (testosterone, glucose/HbA1c, lipids) are the exceptions that DO alter management and should be ordered routinely.

Why This Matters for a 39-Year-Old

• At this age, psychogenic factors are more common, but organic causes must be ruled out 3
• Identifying modifiable risk factors early (diabetes, dyslipidemia, hypogonadism) can reverse ED and prevent future cardiovascular events 2, 3, 6
• Undiagnosed medical conditions may manifest with ED as the first symptom, particularly diabetes 3, 7

Additional Tests to Consider (Not Routine)

Complete Blood Count

• Only order if there are specific clinical indicators suggesting hematologic abnormality 1
• Not part of routine ED workup per AUA guidelines 1

Thyroid Function (TSH)

• Only if clinical signs of thyroid dysfunction are present (weight changes, fatigue, temperature intolerance) 2
• Not routinely recommended 2

Renal Function (Creatinine, eGFR)

• Only if history suggests kidney disease or if PDE5 inhibitor therapy is planned and there's concern about renal impairment 2
• PDE5 inhibitors require dose adjustment in moderate-to-severe renal disease 2

Liver Function Tests (AST, ALT)

• Only if suspicion of hepatic disease exists 2
• Severe liver disease contraindicates PDE5 inhibitor use 2

Prostate-Specific Antigen (PSA)

• Only in select cases, not routine for ED evaluation 4
• May be appropriate if patient has lower urinary tract symptoms or is age-appropriate for prostate cancer screening 4

Common Pitfalls to Avoid

• Don't order extensive laboratory panels "just to be thorough" - the AUA guideline is clear that most tests won't change management 1
• Don't skip testosterone testing - it's the only test with a specific moderate recommendation for all ED patients 1
• Don't forget the cardiovascular implications - ED at age 39 may be the first sign of systemic vascular disease requiring aggressive risk factor modification 1, 2, 3
• Don't order testosterone at any time of day - morning levels are required for accurate assessment 2, 3

What These Results Will Guide

• Low testosterone: Consider testosterone replacement therapy per AUA testosterone deficiency guidelines 1
• Elevated glucose/HbA1c: Initiate diabetes management, as glycemic control improves ED outcomes 2, 6
• Abnormal lipids: Start cardiovascular risk reduction strategies (statins, lifestyle modification) 2, 3, 6
• All normal: Suggests psychogenic etiology; strongly consider mental health referral alongside PDE5 inhibitor trial 1, 3