In a 70-year-old female with hirsutism, which laboratory tests should be ordered?

Laboratory Evaluation for Hirsutism in a 70-Year-Old Woman

In a 70-year-old postmenopausal woman with hirsutism, you should immediately check total testosterone (early morning), free testosterone, and DHEAS to rule out an androgen-secreting tumor, which is the most critical concern in this age group given the high risk of malignancy. 1

Critical Age-Related Considerations

At age 70, hirsutism is never normal and demands aggressive workup. Unlike premenopausal women where PCOS dominates, postmenopausal onset or worsening hirsutism raises immediate concern for:

• Androgen-secreting ovarian tumors (0.2% of hyperandrogenic women, but >50% are malignant) 1
• Adrenal neoplasms
• Ovarian hyperthecosis

The sudden appearance or rapid progression at this age is a red flag that cannot be ignored 2.

Essential Initial Laboratory Panel

Primary Tests (Order These First)

1. Total testosterone - Draw early morning (ideally 8 AM)

   • Use LC/MS assay if available (gold standard) 3
   • Critical threshold: >150 ng/dL (5.2 nmol/L) strongly suggests tumor 4
   • Even moderately elevated levels warrant imaging 1

2. Free testosterone

   • More sensitive than total testosterone for detecting hyperandrogenism 3
   • Can be calculated if you measure SHBG alongside total testosterone 3
   • Direct immunoassays are notoriously inaccurate; use equilibrium dialysis or calculate from total T + SHBG 3

3. DHEAS (dehydroepiandrosterone sulfate)

   • Screens for adrenal source of androgens 1
   • Elevated levels point to adrenal pathology

Secondary Tests Based on Clinical Context

1. 17-hydroxyprogesterone (early morning)

   • Only if suspicion for late-onset congenital adrenal hyperplasia
   • Less likely at age 70 but consider if family history present 1

2. Prolactin

   • Check if any menstrual history of irregularity or galactorrhea
   • Hyperprolactinemia can cause androgen excess 1

3. 24-hour urinary free cortisol OR overnight dexamethasone suppression test

   • Only if clinical features suggest Cushing's syndrome (central obesity, striae, easy bruising, proximal muscle weakness) 1

What NOT to Test

• Do NOT check androstenedione, DHEA, or other androgen metabolites - they add minimal diagnostic value 3
• Thyroid function and ferritin are not causative of hirsutism but may be checked as comorbid conditions affecting hair growth 3

Common Pitfalls to Avoid

1. Timing matters: Testosterone must be drawn in early morning (before 10 AM) for accurate interpretation 1

2. Assay quality: Many commercial testosterone assays are unreliable, especially at low levels. Insist on LC/MS or a validated immunoassay 3

3. Don't dismiss "normal" testosterone: If testosterone is normal but clinical suspicion remains high (rapid progression, virilization signs), recheck with free testosterone in a specialty laboratory 1

4. Age-appropriate interpretation: Postmenopausal women have lower baseline androgens, so even "mildly elevated" levels may be significant 2

Immediate Next Steps Based on Results

If Testosterone >150 ng/dL (5.2 nmol/L):

• Urgent pelvic ultrasound to evaluate for ovarian mass 1
• Consider CT or MRI of adrenals if DHEAS markedly elevated
• Refer to gynecologic oncology or endocrinology immediately 2

If Testosterone 70-150 ng/dL:

• Pelvic ultrasound to look for ovarian pathology (tumor vs. hyperthecosis) 1
• Consider trial of GnRH antagonist (degarelix) - if testosterone drops, suggests benign ovarian source 2

If Testosterone <70 ng/dL but elevated:

• Evaluate for other endocrinopathies based on clinical features
• Consider idiopathic hyperandrogenism (rare at this age)

Additional Diagnostic Maneuvers

Pelvic imaging is mandatory if any testosterone elevation is found, regardless of degree, given the tumor risk in this age group 1, 2. Transvaginal ultrasound is first-line, but MRI may be needed if ultrasound is non-diagnostic.

The evidence strongly supports an aggressive diagnostic approach in postmenopausal hirsutism because the stakes (potential malignancy) are high and the common benign causes (PCOS, idiopathic hirsutism) are unlikely at age 70 1, 2.