Differential Diagnosis for Elevated Testosterone in Female Patients
The differential diagnosis for hyperandrogenemia in women should be systematically approached by first measuring total testosterone and DHEAS, then stratifying based on testosterone levels: markedly elevated testosterone (>2× upper limit normal) suggests androgen-secreting tumors or ovarian hyperthecosis, while mild-to-moderate elevations typically indicate PCOS, non-classical congenital adrenal hyperplasia (NCCAH), or adrenal hyperandrogenism 1, 2.
Diagnostic Algorithm Based on Testosterone Levels
Markedly Elevated Testosterone (>2× Upper Limit Normal)
When testosterone exceeds twice the upper limit of normal, immediately measure DHEAS to localize the source 1:
- DHEAS >600 μg/dL: Indicates adrenal cortical adenoma or adrenal tumor
- Normal DHEAS with very high testosterone: Suggests either:
Critical threshold by LC-MS/MS: Testosterone ≥5.1 nmol/L (147 ng/dL) has 90% sensitivity and 81% specificity for androgen-producing tumors in women with severe hyperandrogenemia 3.
Mild-to-Moderate Testosterone Elevation
The most common causes in this category include:
1. Polycystic Ovary Syndrome (PCOS)
- Most common cause, affecting 5-10% of reproductive-age women 2
- Characterized by perimenarchal onset, chronic anovulation, and gradual progression
- Associated with insulin resistance, low SHBG, and elevated free testosterone 4
- In adolescents with obesity: phenotype shows lower SHBG and higher free testosterone despite lower total testosterone 5
- In lean patients: phenotype shows higher LH, total testosterone, and androstenedione, suggesting neuroendocrine-mediated ovarian androgen production 5
2. Non-Classical Congenital Adrenal Hyperplasia (NCCAH)
- Diagnosed by elevated basal or ACTH-stimulated 17-hydroxyprogesterone (17-OHP) 4
- Alternative diagnostic approach: Significant decrease in testosterone and DHEAS after 2-day dexamethasone suppression test 4
- Presents with oligomenorrhea and hyperandrogenism starting after menarche 4
3. Glucocorticoid-Suppressible Adrenal Hyperandrogenism
- Responds to low-dose glucocorticoids (5-7.5 mg prednisone or 0.25-0.5 mg dexamethasone) 2
- DHEAS levels remain suppressed indefinitely after treatment in most cases 2
4. Cushing's Syndrome
- Rare but must be excluded when hyperandrogenism has recent onset with accompanying signs of hypercortisolism 4
- Screen with overnight dexamethasone suppression test or 24-hour urinary free cortisol 4
5. Hyperprolactinemia
- Consider in women with recent-onset oligomenorrhea and mild hyperandrogenism 4
- Simple screening with serum prolactin level
Special Populations
Postmenopausal Women
In postmenopausal women, the diagnostic threshold is lower: testosterone ≥2.2 nmol/L (63 ng/dL) has 100% sensitivity and 86% specificity for pathologic hyperandrogenism 3.
Postmenopausal hyperandrogenism results from:
- Rapid estrogen decline with slow androgen decline
- Physiological decrease in SHBG
- Worsening of previously undiagnosed conditions (PCOS, CAH, ovarian hyperthecosis) 6
Abrupt onset with virilization in postmenopausal women mandates immediate tumor evaluation 7.
Adolescents
Diagnosis is challenging due to overlap between PCOS symptoms and normal puberty 8. Key distinguishing features:
- Elevation of free or total testosterone above adult female normative values is diagnostic 8
- Obesity-associated hyperandrogenemia: Girls with obesity show 2-3× higher free testosterone across all age groups (6-18 years) compared to healthy-weight girls 9
Important Caveats
False Elevations of Total Testosterone
Elevated SHBG can falsely elevate total testosterone while free testosterone remains normal 1. This occurs with:
- Medications with estrogenic effects (tamoxifen, raloxifene, Op'DDD)
- Hyperthyroidism
- Liver disease
Normal Testosterone with Clinical Hyperandrogenism
When clinical signs (hirsutism, acne) are present but testosterone is normal, consider:
- Low SHBG states (obesity, metabolic syndrome, family history of diabetes) increase free testosterone despite normal total testosterone 1
- Measure free testosterone or calculate free androgen index
Red Flags Requiring Urgent Evaluation
Immediate imaging (MRI of adrenals/ovaries) is indicated when 2, 6:
- Rapid onset of severe hyperandrogenism or virilization
- Testosterone in male range
- Testosterone >5.1 nmol/L by LC-MS/MS (or >2× upper limit normal)
- DHEAS >600 μg/dL
Laboratory Considerations
Total testosterone by radioimmunological assay following extraction or LC-MS/MS is the recommended first-line test 1. Standard immunoassays without extraction are unreliable at low female testosterone levels and show high inter-assay variability 1.