What is the initial workup for a 38-year-old female presenting with fatigue and low libido?

Initial Workup for Fatigue and Low Libido in a 38-Year-Old Female

Begin with morning testosterone measurement (free testosterone or androgen index preferred over total testosterone), thyroid function tests (TSH, free T4), complete blood count to assess for anemia, and comprehensive metabolic panel to screen for metabolic disorders. 1, 2

Laboratory Assessment

Hormonal Evaluation

• Morning testosterone levels (free testosterone or androgen index) should be obtained when there is clinical suspicion of hypogonadism or to reassure the patient 2
• Thyroid function tests (TSH, free T4) are essential if thyroid dysfunction is suspected, as hypothyroidism commonly presents with fatigue and low libido 2
• Prolactin level should be checked if there is loss of libido with low testosterone 2
• Morning cortisol and ACTH levels must be assessed to rule out adrenal insufficiency, particularly if considering DHEA therapy 3

Metabolic and Hematologic Screening

• Complete blood count to evaluate for anemia, which is a clinically relevant contributor to fatigue when present 1
• Fasting glucose or HbA1c to screen for diabetes 2
• Complete metabolic panel if renal or hepatic impairment is suspected 2
• Nutrient status assessment including ferritin, vitamin B12, folate, vitamin D, zinc, and magnesium should be checked, as deficiencies are associated with fatigue 1

Clinical History and Physical Examination

Targeted History Elements

• Medication review is critical, particularly for antidepressants which commonly cause low libido 2
• Sleep quality assessment using validated tools like the Pittsburgh Sleep Quality Index, as sleep disturbances strongly correlate with fatigue 1
• Alcohol consumption, recreational drug use, and smoking history should be documented 2
• Chronic illness screening for diabetes, cardiovascular disease, thyroid disorders, and liver disease 2
• Psychological assessment for distress, anxiety, depression, body-image concerns, and relationship issues 2
• Menopause symptoms including vaginal dryness and dyspareunia should be evaluated 2

Physical Examination

• Blood pressure measurement 2
• Gynecologic examination to assess for vaginal atrophy, anatomic changes, and points of tenderness 2

Validated Screening Tools

Use the Brief Sexual Symptom Checklist for Women as the primary screening tool for sexual dysfunction, with the Female Sexual Function Index (FSFI) for more comprehensive evaluation. 2

For fatigue assessment, use a 0-10 Numeric Rating Scale where scores of 4 or greater indicate moderate to severe fatigue requiring further evaluation 1

Common Pitfalls to Avoid

• Do not attribute symptoms automatically to "normal aging" without thorough workup, as multiple addressable factors often contribute 4
• Never overlook medication side effects, particularly SSRIs and other psychoactive medications that commonly reduce libido 2
• Do not start DHEA before ensuring adequate cortisol replacement if adrenal insufficiency is present, as this can precipitate adrenal crisis 3
• Avoid isolated testing of total testosterone in women; free testosterone or androgen index is preferred 2

When to Refer

Referral to appropriate specialists is indicated when multiple endocrine abnormalities are identified or when initial screening reveals important abnormalities requiring specialized evaluation 2