What is the workup for a patient with decreased libido?

Workup for Decreased Libido

Begin with morning total testosterone measurement in all patients presenting with decreased libido, followed by targeted hormonal and metabolic testing based on initial results and clinical context. 1, 2

Initial Laboratory Evaluation

Essential First-Line Tests

• Morning total testosterone (8-10 AM) is mandatory for all patients with decreased libido, as testosterone <300 ng/dL indicates potential testosterone deficiency requiring further investigation 3, 1, 2

• Free testosterone or androgen index should be measured alongside total testosterone, as this prevents unnecessary endocrine workup in up to 50% of men with low total testosterone who have normal free testosterone levels 1, 2

• Serum prolactin must be measured if testosterone is low OR if loss of libido is the primary complaint, as elevated prolactin universally causes reduced libido 1, 2

• Fasting glucose or HbA1c to screen for diabetes mellitus, which is strongly associated with sexual dysfunction through vascular and neurological mechanisms 1, 2

Secondary Hormonal Testing (If Initial Tests Abnormal)

• LH and FSH should be measured when testosterone is confirmed low on repeat testing to distinguish primary (testicular) from secondary (pituitary/hypothalamic) hypogonadism 1, 2

• TSH and free T4 if thyroid dysfunction is suspected, as both hyperthyroidism and hypothyroidism affect sex hormone binding globulin and can indirectly impact libido 1

• Consider DHEA levels in women with persistent low libido despite optimized hormone replacement therapy 3, 1

Clinical History Components

Sexual and Relationship History

• Duration, onset, and severity of decreased libido should be systematically documented using validated instruments like the Sexual Desire Inventory-2 2

• Partner-related factors including partner's sexual dysfunction (erectile dysfunction, vaginal dryness), relationship satisfaction, and domestic/dyadic relationship disturbances must be explored, as these are major contributors to primary reduced libido 2, 4

• Distinguish primary from secondary reduced libido: Primary occurs in otherwise healthy individuals with relationship issues, while secondary is associated with hypogonadism, hyperprolactinemia, or psychopathology 4

Medication Review

• SSRIs (paroxetine, sertraline, citalopram, fluoxetine) commonly cause reduced libido in 6% of patients, with sertraline specifically causing decreased libido in 6% versus 1% with placebo 1, 5

• Beta-blockers are strongly associated with sexual dysfunction; consider switching to ACE inhibitors, calcium channel blockers, or loop diuretics (furosemide, bumetanide) which have lower risk 1

• 5-alpha reductase inhibitors (finasteride, dutasteride) cause decreased libido in 4.5-10% of patients versus 1.3-6.2% with placebo, and can cause persistent sexual dysfunction 3, 1

• Antipsychotics can elevate prolactin and suppress libido 1

• Antiandrogens (cyproterone acetate, spironolactone, flutamide, bicalutamide) directly block androgen receptors 1

• Opioids, corticosteroids, and H2-receptor antagonists are associated with reduced libido 1

Medical Comorbidities Assessment

• Cardiovascular disease and hypertension impair sexual function through vascular mechanisms 1

• Depression and anxiety are major contributors to low libido and nearly double the prevalence of reduced libido; these should be addressed before treating sexual dysfunction 1, 2

• Chronic kidney disease, liver failure, metabolic syndrome (obesity, insulin resistance) reduce libido 1

• Neurological conditions (multiple sclerosis, Parkinson's disease) affect sexual desire 1

• Cancer treatment history including prostate cancer treatment, pelvic radiation, chemotherapy, and hormonal cancer treatments suppress libido 1

Physical Examination Focus

Endocrine and Cardiovascular Assessment

• Signs of hypogonadism: decreased body hair, gynecomastia, reduced muscle mass, testicular atrophy 2

• Body mass index and body habitus to assess for obesity-related hypogonadism 2

• Cardiovascular examination: blood pressure (supine and standing), cardiac auscultation, carotid bruits, femoral and pedal pulses to assess cardiovascular risk 2

• Genital and prostate examination in men 2

Special Considerations for Athletes

• Low energy availability in male athletes at <20-25 kcal/kg fat-free mass/day may suppress testosterone and cause reduction in libido and loss of nocturnal penile tumescence 3

• Serial/longitudinal testosterone measurements may be more beneficial than single measurements in athletes 3

Common Pitfalls to Avoid

• Do not accept a single low testosterone measurement: Always repeat abnormal testosterone levels before initiating treatment 2

• Do not overlook relationship factors: Dissatisfaction with relationships is the most common factor in patients with depressed desire and characterizes primary reduced libido 6, 4

• Do not assume all low total testosterone requires treatment: Up to 50% of men with low total testosterone have normal free testosterone due to low sex hormone-binding globulin, particularly in obesity 1

• Do not forget to assess suicide risk: When depression is identified, formal suicide risk assessment should be undertaken as depression significantly elevates suicide risk 3