Laboratory Workup for Hirsutism with Menstrual Irregularities
For a patient presenting with abnormal hair growth and irregular menses, obtain early morning (before 8-10 AM) total testosterone, TSH, prolactin, and 17-hydroxyprogesterone levels as your initial laboratory workup 1, 2.
Initial Essential Tests
The following labs should be drawn in all patients with hirsutism and menstrual irregularities to exclude disorders that mimic polycystic ovary syndrome (PCOS), which is the most common cause (80-90% of cases) 1, 2:
- Total testosterone (early morning, ideally days 4-10 of menstrual cycle if cycling regularly)
- TSH - thyroid disease presents with irregular cycles
- Prolactin - hyperprolactinemia can cause amenorrhea or hirsutism
- 17-hydroxyprogesterone (17-OHP) (early morning, follicular phase) - screens for non-classic congenital adrenal hyperplasia, found in 1.5-6.8% of hyperandrogenic patients 1
Additional Testing Based on Initial Results
If Total Testosterone is Normal but Clinical Suspicion Remains High:
Recheck with both total AND free testosterone in a specialty laboratory 2. This is particularly important if:
- Risk factors are present (central obesity, acanthosis nigricans, family history of diabetes)
- Hirsutism progresses despite therapy
- Patient is from high-risk ethnic group
If Total Testosterone is Elevated:
Proceed with expanded workup 2:
- Pregnancy test (if amenorrheic)
- DHEAS (dehydroepiandrosterone sulfate) - evaluates adrenal androgen production
- Pelvic ultrasonography - detects ovarian neoplasm or polycystic ovary morphology
- Sex hormone-binding globulin (SHBG) with calculation of free androgen index
Red Flag Scenarios Requiring Urgent Additional Workup:
If any of the following are present, consider androgen-secreting tumor (0.2% of cases, >50% malignant) 2:
- Sudden onset or rapid progression of hirsutism
- Virilization signs (clitoromegaly, increased muscularity, deepening voice)
- Abdominal or pelvic mass
- Very high testosterone levels
In these cases, add:
- CT imaging of adrenals
- Detailed pelvic imaging
Selective Testing for Other Endocrinopathies:
Only order if clinical features suggest these diagnoses 1, 2:
- 24-hour urinary free cortisol or overnight dexamethasone suppression test - if Cushing's features (proximal muscle weakness, easy bruising, striae)
- IGF-1 - if acromegaly features (frontal bossing, enlarged hands/feet)
High-Risk Populations Requiring 17-OHP Testing
Always measure 17-OHP in early morning follicular phase if patient is 2:
- Ashkenazi Jewish (prevalence 1 in 27)
- Hispanic (1 in 40)
- Slavic (1 in 50)
- Positive family history of congenital adrenal hyperplasia
Metabolic Screening for PCOS Patients
Once PCOS is diagnosed (after exclusion of other causes), assess cardiovascular and metabolic risk 2:
- Oral glucose tolerance test or fasting glucose and HbA1c
- Complete lipid profile
These are critical because PCOS carries significant long-term morbidity from metabolic syndrome, type 2 diabetes, and cardiovascular disease.
Common Pitfalls to Avoid
Timing matters: Testosterone should be drawn early morning (before 8-10 AM) when levels peak, ideally on cycle days 4-10 in regularly cycling women 2
Don't skip the exclusion tests: PCOS is a diagnosis of exclusion. Missing thyroid disease, hyperprolactinemia, or non-classic CAH can lead to inappropriate treatment 1
Medication history is essential: Ask specifically about anabolic steroids (athletes, bodybuilders), danazol (endometriosis patients), and valproic acid (seizure patients) - these cause iatrogenic hirsutism 2
Ethnic considerations: Even mild hirsutism in Asian women may indicate hyperandrogenism, whereas Mediterranean or Middle Eastern women may have more terminal hair normally 2
Don't rely solely on hirsutism severity: The Ferriman-Gallwey score correlates poorly with androgen levels due to variable follicular sensitivity 2. A patient with mild hirsutism but menstrual irregularities still warrants full workup.