A two-step extraction method to measure fecal steroid hormones in female cynomolgus monkeys (Macaca fascicularis).

We developed a two-step extraction method for measuring fecal steroid concentrations. In the first step, distilled water was used to extract steroids from fecal samples. In the second step, a mixture of organic solvents (hexane and ether) was used to re-extract water extracts that had been transferred to a glass tube. A portion of the upper layer of the organic solvents was transferred to separate assay-tubes for measurement of estradiol (E2) or progesterone (P), and the organic solvents were evaporated in vacuo. After phosphate-buffered saline was added to each tube, commercially supplied radioimmunoassay (RIA) kits were used to determine the steroids. We demonstrated the advantages and reliability of this method by using it to assay the steroid hormone concentrations in fecal samples and serum samples collected on the same day from female cynomolgus monkeys who showed normal menstrual cycles and from monkeys who had induced hyperfunction of ovarian steroidgenesis. Different fecal samples from each monkey were used to determine the recovery rate of each steroid in water extraction from the fecal samples and the reproductivity of hormone concentrations in the fecal samples. The results demonstrate that this two-step method is simple and effective for measuring fecal steroids for monitoring the reproductive status of cynomolgus monkeys, without having to collect serum samples.