What initial tests should be done to evaluate erectile dysfunction?

Initial Laboratory and Diagnostic Testing for Erectile Dysfunction

All men presenting with erectile dysfunction should undergo morning serum total testosterone measurement, fasting glucose or HbA1c, and a fasting lipid panel as the core initial laboratory workup. 1, 2

Essential Laboratory Tests

Hormonal Assessment

• Morning serum total testosterone is mandatory for all men with ED, as testosterone deficiency (defined as <300 ng/dL with symptoms) is present in approximately 36% of men seeking consultation for sexual dysfunction and is linked to both ED and increased cardiovascular mortality 1
• Morning measurement is critical due to diurnal variation in testosterone levels 2
• If hypogonadism is suspected based on clinical findings (decreased libido, loss of spontaneous erections, testicular or muscle atrophy), free or bioavailable testosterone should be measured instead of total testosterone 2

Metabolic and Cardiovascular Risk Assessment

• Fasting glucose and/or HbA1c must be obtained, as ED is frequently the first presenting symptom of diabetes mellitus 2, 3
• Complete fasting lipid profile (total cholesterol, HDL, LDL, triglycerides) is essential since ED shares identical risk factors with coronary artery disease and serves as a risk marker for underlying cardiovascular disease 1, 2, 4

Clinical Assessment Components

History Taking

• Document ED severity using validated questionnaires: International Index of Erectile Function (IIEF) or Sexual Health Inventory for Men (SHIM) 1, 2
• Assess onset, duration, ability to attain versus maintain erections, presence of nocturnal/morning erections (suggests psychogenic component), and situational factors 1
• Obtain comprehensive cardiovascular risk factor history: age, hypertension, dyslipidemia, diabetes, abdominal obesity, family history of premature CVD (father <55 years, mother <65 years), smoking, alcohol use, physical inactivity, and symptoms of obstructive sleep apnea 1
• Review all medications, as approximately 25% of ED cases are drug-related and readily reversible 5

Physical Examination

• Measure blood pressure, waist circumference, and body mass index 1
• Perform cardiac auscultation and assess for carotid bruits, fundal arterial changes, and palpate femoral and pedal pulses to detect peripheral vascular disease 1
• Examine penis while stretched from pubic bone to coronal sulcus for plaques or deformities suggestive of Peyronie's disease 1
• Assess penile skin lesions and urethral meatus placement 1

Electrocardiogram

• Resting ECG should be obtained in men with hypertension or diabetes (class IIa recommendation) and considered in asymptomatic men without these conditions (class IIb recommendation) 1

Additional Testing for Select Patients

When Testosterone Replacement is Considered

• Prostate-specific antigen (PSA) and digital rectal examination should be performed as baseline measurements before initiating testosterone therapy 2

When First-Line Therapies Fail

• Specialized neurological testing may include bulbocavernosus reflex testing, dorsal sensory nerve conduction studies, and pudendal nerve somatosensory evoked potentials 2

Critical Clinical Pitfalls

• Do not overlook cardiovascular risk assessment: ED in men aged 30-60 years should alert physicians to increased CVD risk independent of Framingham Risk Score, as ED may precede cardiovascular events by years 1
• Do not assume normal urinalysis or lack of symptoms excludes serious pathology: Diabetic autonomic neuropathy may mask typical pain responses 6
• Do not interpret testosterone levels drawn at non-morning times, as this will yield falsely low results 2
• Do not order digital rectal examination routinely for ED evaluation alone, though benign prostatic hyperplasia commonly coexists and may warrant separate evaluation 1
• Do not proceed with specialized testing before completing basic laboratory workup, as glucose/HbA1c and lipids are the only routine serum studies likely to alter ED management beyond testosterone 1