What lab workup is recommended for a patient presenting with erectile dysfunction?

Laboratory Workup for Erectile Dysfunction

The essential laboratory workup for erectile dysfunction should include morning serum total testosterone, fasting glucose/HbA1c, and lipid profile, as these tests can identify common underlying causes and guide appropriate treatment. 1, 2

Core Laboratory Tests

Required Tests:

• Morning serum total testosterone

  • Must be measured in all men with ED 1
  • Should be drawn in the morning when levels are highest
  • Testosterone deficiency is defined as <300 ng/dL with symptoms 2

• Fasting glucose/HbA1c

  • Essential for detecting undiagnosed diabetes 2
  • Studies show 15% of ED patients have previously undiagnosed elevated glucose levels 3

• Lipid profile

  • Critical for cardiovascular risk assessment 2
  • ED is a risk marker for underlying cardiovascular disease 1

Additional Testing Based on Clinical Presentation

Consider in Specific Situations:

• Prostate-specific antigen (PSA)

  • Required as baseline if testosterone therapy is planned 1
  • Should be accompanied by digital rectal examination 1

• Thyroid function tests

  • When symptoms of thyroid dysfunction are present

• Prolactin levels

  • Consider when testosterone is low or when symptoms suggest pituitary dysfunction

Clinical Context for Laboratory Testing

Laboratory testing for ED should be performed within the context of:

1. Thorough medical history

   • Age, comorbidities, medications, surgical history
   • Family history of vascular disease
   • Substance use (tobacco, alcohol, recreational drugs)

2. Sexual history

   • Onset and progression of symptoms (sudden vs. gradual)
   • Quality of erections (nocturnal, morning, masturbatory)
   • Situational factors

3. Physical examination

   • Blood pressure and cardiovascular assessment
   • Genital examination for penile abnormalities or plaques
   • Assessment for secondary sexual characteristics

Common Pitfalls to Avoid

• Not measuring testosterone levels - This is a moderate recommendation with Grade C evidence from the AUA 1
• Assuming ED in young men is purely psychogenic - At least 15-20% have organic causes 2
• Overlooking ED as a marker for cardiovascular disease - ED often precedes cardiovascular events by 3-5 years
• Excessive testing - Most cases can be managed with the core tests listed above 1
• Failing to recognize ED as a potential indicator of undiagnosed diabetes - Studies show 12.1% of ED patients with normal fasting glucose have diabetes when given an OGTT 3

Special Considerations

• In patients under 40 years old, while psychogenic causes are more common, organic causes should still be investigated 2
• ED can be the first symptom of systemic disease - 15.7% of patients with vascular ED show electrocardiographic alterations without cardiac symptoms 3
• Specialized testing (vascular studies, nocturnal penile tumescence) is rarely needed for initial evaluation and should be reserved for specific cases 1, 4

Remember that ED is often multifactorial, with both organic and psychological components that may need to be addressed for successful treatment.