Changes in urinary homocysteine following synthetic steroidal estrogen and progestogen administration to rats

The present work involved the administration of both ethynyl estradiol and levonorgestrel to groups of rats, followed by determination of the homocysteine excretion rate in urine. The results indicate that a statistically significant difference exists between the excreted levels of homocysteine in the urine of both control and levonorgestrel-treated rats and the levels shown by rats treated with ethynyl estradiol. The implications of these results are discussed, especially with respect to observations which indicate that homocysteine may be a precipitating factor in the development of thrombosis. Also included in this paper is a study which confirms the identity of the HPLC peak as being homocysteine by forming a radioactive derivative of this particular sulphydryl-containing amino acid, and then analysing the resulting mixture by TLC.