Laboratory Workup for Erectile Dysfunction
Morning serum total testosterone is the only mandatory laboratory test for all men presenting with erectile dysfunction, while fasting glucose (or HbA1c) and lipid profile should also be obtained to identify cardiovascular risk factors and diabetes. 1, 2, 3
Mandatory Laboratory Testing
Morning Total Testosterone
- Measure morning serum total testosterone in every man with ED (Moderate Recommendation; Evidence Level: Grade C). 1, 2, 3
- Testosterone deficiency is defined as total testosterone <300 ng/dL with accompanying symptoms. 2, 3
- This is critical because hypogonadism requires separate management and commonly explains PDE5 inhibitor treatment failure. 2, 3
- If total testosterone is low or borderline, consider measuring bio-available or free testosterone for more accurate assessment. 1
Metabolic Screening
- Obtain fasting blood glucose or HbA1c to screen for diabetes mellitus, as 15% of ED patients have previously undiagnosed diabetes and another 12.1% have abnormal glucose tolerance. 1, 4, 5
- Measure fasting lipid profile to assess cardiovascular risk, as dyslipidemia is a major risk factor for ED and underlying vascular disease. 1, 4, 6, 7
Optional Laboratory Tests (Based on Clinical Context)
Thyroid Function
- Measure thyroid-stimulating hormone (TSH) if clinical signs of thyroid dysfunction are present, as both hyperthyroidism and hypothyroidism cause ED that resolves in 50% of patients with hormone normalization. 6, 8
Prolactin
- Prolactin measurement is not routinely necessary but should be obtained when testosterone levels are low (<300 ng/dL), as hyperprolactinemia suppresses testosterone and causes ED. 1, 8
- Correcting elevated prolactin levels treats the sexual dysfunction. 8
Critical Clinical Context
Why This Workup Matters
- ED is a sentinel marker for cardiovascular disease, presenting on average 3 years before coronary artery disease symptoms. 1, 2, 3, 6
- Men with ED have significantly increased risk of coronary, cerebrovascular, and peripheral vascular diseases. 6
- The laboratory workup identifies treatable underlying conditions (diabetes, hypogonadism, dyslipidemia) that contribute to ED and require management independent of ED treatment. 1, 4, 5
What NOT to Order Routinely
- No other routine serum studies are likely to alter ED management beyond glucose/HbA1c, lipids, and testosterone. 1
- Prostate-specific antigen (PSA) is not required for ED evaluation unless testosterone replacement is being considered or benign prostatic hyperplasia evaluation is warranted. 7
- Adrenal hormone testing is not indicated in routine ED workup. 8
Common Pitfalls to Avoid
- Failing to check testosterone is the most common laboratory error, as this explains poor response to PDE5 inhibitors and requires separate treatment. 2, 3
- Missing diabetes screening overlooks a condition present in 15-27% of ED patients that significantly impacts treatment success and overall health. 1, 5
- Skipping cardiovascular risk assessment misses the opportunity to identify and treat life-threatening vascular disease for which ED may be the first symptom. 1, 2, 3, 6