Laboratory Screening for Erectile Dysfunction
Morning serum total testosterone is the only mandatory laboratory test for all men presenting with ED, while glucose/HbA1c and lipid profile should be obtained to identify critical cardiovascular risk factors and diabetes. 1
Essential Laboratory Tests
Required for All Patients
- Morning serum total testosterone must be measured in all men with ED to identify testosterone deficiency (defined as total testosterone <300 ng/dL with symptoms), as this is the only lab test with a moderate-strength recommendation from the American Urological Association. 1
Strongly Recommended for Cardiovascular Risk Assessment
Fasting glucose or HbA1c should be obtained because ED is a risk marker for cardiovascular disease as strong as cigarette smoking or family history of myocardial infarction, and diabetes significantly reduces treatment efficacy. 1, 2
Fasting lipid profile (total cholesterol, LDL, HDL, triglycerides) is critical since the Princeton Consensus Conference identified ED as a substantial independent predictor of future cardiac events, with 48.4% of ED patients having abnormal cholesterol levels. 1, 2, 3
Selective Laboratory Tests
Consider Based on Clinical Context
Prolactin levels should be measured if testosterone is low or if there are symptoms suggesting hyperprolactinemia (decreased libido, gynecomastia), though abnormalities occur in only 0.5-4.6% of patients. 3, 4, 5
Thyroid-stimulating hormone (TSH) may be ordered if clinical signs of thyroid dysfunction are present, but routine screening has a very low yield (0.13-4.0% abnormal). 3, 6, 4
Renal function tests (creatinine, eGFR) should be assessed if kidney disease is suspected, as 11.9% of ED patients have renal insufficiency and PDE5 inhibitors require dose adjustment in moderate-to-severe renal impairment. 2, 3
Liver function tests (AST, ALT) are indicated only if hepatic disease is suspected, as severe liver disease contraindicates PDE5 inhibitor use. 2
Key Clinical Principles
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 that beyond testosterone, glucose/HbA1c, and lipids, additional laboratory testing should be selective and guided by specific clinical findings rather than routine screening. 1
Important Caveats
Timing matters: Testosterone must be measured in the morning due to diurnal variation, ideally between 7-11 AM. 1, 4
ED as a sentinel event: The diagnosis of ED provides a pivotal opportunity to identify and manage cardiovascular risk factors that impact both mortality and quality of life, making glucose and lipid screening particularly important even though they may not immediately alter ED-specific management. 1
High prevalence of metabolic abnormalities: In men presenting with ED, 52.9% have elevated HbA1c and 48.4% have elevated cholesterol, making these tests clinically valuable for overall health management. 3