What is the recommended history, physical examination, and laboratory workup for a woman presenting with diffuse hair thinning?

Workup for Diffuse Hair Thinning in Women

A focused history targeting menstrual patterns, androgen excess symptoms, metabolic risk factors, and medication use, combined with a targeted physical examination for signs of hyperandrogenism and metabolic disease, should guide initial laboratory testing that includes thyroid function, iron studies, and androgen levels. 1

History

Menstrual and Reproductive History

• Document menstrual cycle regularity, duration, and onset of irregularities to identify chronic anovulation, which is associated with polycystic ovary syndrome (PCOS) and can present with hair thinning 1
• Assess contraceptive use and fertility history, as these provide clues to underlying hormonal dysfunction 1

Signs of Androgen Excess

• Determine onset and duration of hair thinning and whether it is accompanied by other signs of androgen excess such as acne, hirsutism, or deepening voice 1
• Ask specifically about pattern of hair loss (diffuse vs. androgenic pattern) and rate of progression 1

Medication and Substance Use

• Review all medications, particularly exogenous androgens, which can cause hair thinning 1
• Document use of oral contraceptives, as these can both mask and treat androgen-related hair loss 1

Lifestyle and Metabolic Factors

• Assess diet, exercise patterns, alcohol use, and smoking, as these relate to metabolic dysfunction 1
• Document weight changes and eating patterns, particularly caloric restriction or excessive exercise that may suggest functional hypothalamic amenorrhea 1

Family History

• Obtain family history of cardiovascular disease, diabetes, and early myocardial infarction (before age 55 in male relatives, before age 65 in female relatives), as PCOS patients have increased cardiovascular risk 1
• Ask about family history of hair loss, thyroid disease, and autoimmune conditions 1

Physical Examination

Androgen Excess Assessment

• Examine for acne, male-pattern balding, and clitoromegaly as signs of significant hyperandrogenism 1
• Assess distribution and pattern of body hair to quantify hirsutism 1
• Perform pelvic examination to assess for ovarian enlargement, though this is often normal even in PCOS 1

Metabolic and Endocrine Signs

• Look for acanthosis nigricans on the back of neck, beneath breasts, axillae, or vulva as a marker of insulin resistance 1
  • If acanthosis nigricans is present, consider associated insulinoma or malignancy, particularly gastric adenocarcinoma 1
• Calculate body mass index and waist-hip ratio to assess for obesity and central adiposity 1

Thyroid Assessment

• Palpate thyroid gland for enlargement or nodules 1

Cushing's Syndrome Screening

• If history suggests Cushing's syndrome, examine for buffalo hump, moon facies, hypertension, abdominal striae, centripetal fat distribution, easy bruising, or proximal myopathies 1

Laboratory Workup

First-Tier Testing

• Thyroid-stimulating hormone (TSH) to exclude thyroid disease, a common cause of hair thinning 1
• Serum ferritin to assess iron stores, as iron deficiency is a reversible cause of hair loss 1
• Total testosterone or bioavailable/free testosterone to evaluate for ovarian hyperandrogenism 1
• Prolactin level to exclude hyperprolactinemia 1

Metabolic Screening (Particularly if PCOS Suspected)

• Fasting glucose followed by 2-hour glucose after 75-gram oral glucose load to screen for diabetes and glucose intolerance, as women with PCOS have demonstrated increased risk 1
• Fasting lipid profile including total cholesterol, LDL, HDL, and triglycerides, as PCOS patients frequently have dyslipidemia 1

Additional Testing Based on Clinical Presentation

• If Cushing's syndrome is suspected based on physical findings, proceed with appropriate screening tests 1
• If signs suggest androgen-secreting tumor (rapid onset, severe virilization, very elevated testosterone), imaging of ovaries and adrenal glands is indicated 1
• Consider testing for nonclassic congenital adrenal hyperplasia in patients with significant hyperandrogenism 1

Key Clinical Pitfalls

Avoid extensive laboratory testing without a focused history and physical examination, as studies demonstrate that 76% of diagnoses are made from history alone, with physical examination and laboratory investigation serving primarily to confirm diagnoses and exclude alternatives 2. The history and physical examination should guide selective testing rather than ordering comprehensive panels 3, 4.

Do not overlook functional hypothalamic amenorrhea in women with low body weight or excessive exercise, as this can present with amenorrhea and may be misdiagnosed as PCOS if polycystic ovarian morphology is present on ultrasound 1. These patients typically have low LH:FSH ratio (<1 in 82% of cases) and signs of estrogen deficiency 1.

Remember that acanthosis nigricans warrants consideration of malignancy, not just insulin resistance, particularly gastric adenocarcinoma 1.