What is the next step in evaluating a 55-year-old woman with normal CBC, thrombocytosis (platelet count 421 ×10⁹/L), normal vitamin B12, normal urinalysis, mildly elevated alanine aminotransferase (ALT 39 U/L), dyslipidemia with low HDL, normal follicle‑stimulating hormone (FSH) and luteinizing hormone (LH), elevated testosterone, and normal thyroid‑stimulating hormone (TSH)?

Next Step: Measure DHEAS and Free Testosterone

The next step is to measure DHEAS (dehydroepiandrosterone sulfate) and free testosterone to further evaluate this patient's hyperandrogenism and determine its source 1, 2.

Rationale for This Approach

This 55-year-old woman presents with elevated testosterone (1.6, which appears high) in the context of dyslipidemia and mild thrombocytosis. The key priority is determining whether this represents a serious androgen-secreting tumor versus a more benign condition like PCOS or metabolic syndrome.

Why DHEAS is Critical

• If DHEAS is >600 µg/dL (16,000 nmol/L), this strongly suggests an androgen-secreting adrenal cortical adenoma, which requires urgent abdominal imaging 2
• If DHEAS is normal with elevated testosterone, the differential shifts to ovarian sources: either ovarian hyperthecosis (often with insulin resistance) or an androgen-secreting ovarian tumor 2
• DHEAS is primarily of adrenal origin and helps localize the source of androgen excess 1, 2

Why Free Testosterone Matters

• Free testosterone may detect subtle hyperandrogenemia even when total testosterone appears only mildly elevated 1
• In the context of dyslipidemia and low HDL, this patient likely has metabolic syndrome with reduced SHBG (sex hormone-binding globulin), which increases free testosterone 1, 2
• Obese women with hyperinsulinemia commonly have elevated free testosterone due to reduced SHBG 1

Additional Considerations

The Thrombocytosis (421 × 10⁹/L)

This mild elevation (normal upper limit ~450 × 10⁹/L) is most likely reactive/secondary thrombocytosis given the clinical context 3, 4. The most common causes are tissue damage, infection, malignancy, and chronic inflammation 4.

• No immediate action needed for this platelet count unless it persists or rises further
• Secondary thrombocytosis rarely causes thrombotic complications unless other risk factors are present 4
• If platelets remain elevated after addressing the hyperandrogenism workup, consider repeat CBC in 2-3 months

The Mildly Elevated ALT (39 U/L)

This minimal elevation in the context of dyslipidemia and likely metabolic syndrome suggests nonalcoholic fatty liver disease (NAFLD) 5. This is consistent with the overall metabolic picture and hyperandrogenism.

Laboratory Timing and Quality

Critical caveat: Ensure testosterone was measured in a reliable laboratory using appropriate methodology 1. Many commercial labs have inaccurate reference ranges for female testosterone levels, potentially leading to false-positive or false-negative results 1. Ideally, samples should be obtained during the first 7 days of the menstrual cycle (though this patient may be perimenopausal given her age) 1.

If Initial Testing Shows Concerning Results

If testosterone is ≥2× the upper limit of normal:

• Immediately measure DHEAS 2
• If DHEAS >600 µg/dL → urgent abdominal CT/MRI for adrenal tumor
• If DHEAS normal → pelvic ultrasound for ovarian masses and consider ovarian hyperthecosis

If free testosterone is elevated with normal total testosterone:

• Measure SHBG to confirm the mechanism 2
• Assess for metabolic syndrome components (already evident with dyslipidemia)
• Consider 17-hydroxyprogesterone to rule out nonclassic congenital adrenal hyperplasia 1

Common Pitfalls to Avoid

1. Don't dismiss mildly elevated testosterone in a postmenopausal/perimenopausal woman—tumors can present with modest elevations
2. Don't assume PCOS without excluding more serious causes first
3. Don't rely on a single testosterone measurement from an unvalidated commercial lab
4. Don't order pelvic ultrasound first—biochemical localization with DHEAS is more specific 2