EXCRETORY PROFILE OF INHIBIN-LIKE PEPTIDE (ILP) DURING HUMAN MENSTRUAL-CYCLE - A PROBABLE MARKER FOR DETERMINATION OF FERTILE PERIOD

The excretory profile of inhibin-like peptide (10.4 kDa) and its inter relationship with urinary LH, FSH, oestrone glucuronide (E(1)G) and pr egnanediol glucuronide (PdG) during the menstrual cycle were studied. These hormones/metabolites were estimated in daily early morning urine samples obtained from 20 regularly menstruating women. The data revea led that the excretory profile of inhibin-like peptide (ILP) follows a pattern similar to that of E(1)G. In 17 cycles, ILP peaked 3-4 days p rior to the urinary LH peak. A value of 70 ng/mg creatinine (95th cent ile of ILP levels obtained between 2 and 4 days prior to urinary LH pe ak and also 5th centile of peak ILP levels) was considered as an indic ator of the start of the fertile period. A value of PdG more than 2 mu g/mg creatinine on two consecutive days was considered as an end of t he fertile period. The entire fertile period could be determined in 18 out of 20 cycles when criteria based on ILP and PdG levels were appli ed (accuracy, 90%), whereas it could be determined in 13 out of 20 cyc les when criteria based on E(1)G and PdG levels were applied (accuracy , 65%). Thus, ILP levels in urine may prove to be one of the signals f or determining the start of fertile period.