Effect of Norplant implants on the pituitary-adrenal axis function and reserve capacity.

ABSTRACT

PIP: To ensure that Norplant contraceptive implants are not associated with a risk of pituitary-adrenal suppression, a series of laboratory tests were conducted in 15 women both before and 6 months after Norplant insertion. Comparisons of hormonal profiles before and after Norplant insertion revealed a significant drop in morning serum cortisol levels (404.33 +or- 84.07 nmol/l vs. 353.67 +or- 56.65 nmol/l, p 0.05), but no significant change in evening readings. The observed changes in morning cortisol values were still within the normal range. Serum ACTH values and 24-hour urinary 17-hydroxy steroids, 17-ketogenic steroids, and 17-ketosteroids were not different after insertion compared to baseline. Before Norplant insertion, injection of synthetic ACTH resulted in a 259.59 +or- 169.53% increase in the mean level of serum cortisol 5 hours later; 6 months after Norplant insertion, the percent rise above baseline was 165.85 +or- 91.64%. The significantly lower adrenal response among Norplant users (although still within normal limits) is presumably due to a local inhibition of the adrenal itself and not of the hypothalamic-pituitary axis. Although these findings suggest a minimal suppressive effect of prolonged microdose release of levonorgestrel from Norplant implants, the suprarenal response to acute or prolonged stresses (e.g., surgical operations or shock) in Norplant users requires investigation.