Assessment of theca cell function prior to controlled ovarian stimulation: the predictive value of serum basal/stimulated steroid levels

BACKGROUND Serum androgen levels correlate with ovarian sensitivity to follicle-stimulating hormone (FSH) but in practice, standard baseline serum testosterone (T) levels prior to in-vitro fertilization (IVF) may not be the most appropriate marker for determination. METHODS Infertile women enrolled in an IVF programme were included in this study. Serum T and Δ4-androstenedione (A), and the androgen precursor 17-hydroxyprogesterone (17-OHP) were measured before and 24 h after a gonadotrophin-releasing hormone agonist stimulation test (GAST). An early follicular phase antral follicle count (AFC) was also performed. Patients were subsequently enrolled in a long gonadotrophin-releasing hormone agonist protocol with a standard FSH dose (150 IU) for 7 days to assess the association between androgen levels and ovarian responsiveness to FSH. RESULTS The GAST elicited a significant increase in serum androgen levels that was well correlated with AFC. 17-OHP showed the greatest response to GAST and strongest correlation with AFC. The 17-OHP response to GAST differentiated patients with high ovarian reserve (OR) from those with low or normal OR as assessed by AFC, whereas only the estradiol response could differentiate those with low AFC. GAST-stimulated serum levels of 17-OHP were also correlated with ovarian response to FSH. Using receiver operating characteristic curve analysis, stimulated 17-OHP levels were predictive of the ovarian response to controlled ovarian stimulation, with similar power to that observed with AFC but lower power than with anti-Müllerian hormone. CONCLUSIONS Serum androgen levels following GAST are correlated with AFC and ovarian response to FSH. Serum T is a less sensitive marker of theca cell function than 17-OHP.