Can a high testosterone-to-estrogen ratio establish androgen excess?

A high testosterone-to-estrogen relationship alone is not a validated diagnostic basis for androgen excess in women. This is especially important at age 50, when declining or fluctuating estradiol can increase the apparent ratio without an abnormal testosterone concentration.

Clinical and laboratory interpretation

• Biochemical hyperandrogenism should be assessed from actual androgen concentrations, units, laboratory reference intervals, symptoms, and menstrual history—not from a testosterone:estradiol ratio cutoff.
• A high ratio may reflect low or variable estradiol rather than increased testosterone. Thus, it cannot identify either the presence or cause of androgen excess.
• Recommended initial testing includes total testosterone, SHBG, and a reliable estimate of free testosterone. SHBG is essential because altered binding can substantially change bioavailable testosterone even when total testosterone is unchanged.
• Calculated free testosterone is generally more robust than the free androgen index; the latter can overestimate free testosterone when SHBG is <30 nmol/L.

Measurement and timing

• Total testosterone should be measured with a validated assay, preferably liquid chromatography–tandem mass spectrometry (LC–MS/MS). Routine direct immunoassays can be inaccurate at the low testosterone levels common in women; discordant or unexpected findings warrant LC–MS/MS confirmation.
• Morning, fasting sampling and, when feasible, early-follicular-phase collection improve comparability. Irregular cycles should not prevent evaluation, but cycle and menopausal status remain important for interpreting estradiol.
• Depending on clinical features, further testing may include DHEAS, androstenedione, and 17-hydroxyprogesterone.

Bottom line

• A reported high testosterone-to-estrogen relationship cannot establish androgen excess without the underlying values, assay method, timing, SHBG, and free-testosterone context; direct, validated androgen testing is required.