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 conce ntrations. In the first step, distilled water was used to extract steroids from fecal samples. In the second step, a mixture of organic solvents (hexa ne and ether) was used to re-extract water extracts that had been transferr ed to a glass tube. A portion of the upper layer of the organic solvents wa s 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 suppli ed radioimmunoassay (RIA) kits were used to determine the steroids. We demo nstrated the advantages and reliability of this method by using it to assay the steroid hormone concentrations in fecal samples and serum samples coll ected on the same day from female cynomolgus monkeys who showed normal mens trual cycles and from monkeys who had induced hyperfunction of ovarian ster oidgenesis. Different fecal samples from each monkey were used to determine the recovery rate of each steroid in water extraction from the fecal sampl es and the reproductivity of hormone concentrations in the fecal samples. T he results demonstrate that this two-step method is simple and effective fo r measuring fecal steroids for monitoring the reproductive status of cynomo lgus monkeys, without having to collect serum samples. Am. J. Primatol. 48: 291-298, 1999. (C) 1999 Wiley-Liss, Inc.