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Free and protein‐bound progesterone during normal and luteal phase defective cycles
Author(s) -
Minassian S.S.,
Wu C.H.
Publication year - 1993
Publication title -
international journal of gynecology and obstetrics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.895
H-Index - 97
eISSN - 1879-3479
pISSN - 0020-7292
DOI - 10.1016/0020-7292(93)90324-p
Subject(s) - luteal phase , follicular phase , endocrinology , medicine , menstrual cycle , transcortin , globulin , hormone
OBJECTIVES: New methods for the measurement of the percent free (%FreeP) and percent corticosteroid binding globulin‐bound (%CBG‐B) fractions of plasma progesterone (P) are described. METHODS: Modifications of previously reported equilibrium dialysis and charcoal adsorption assays were used. P binding was analyzed in single midluteal samples of 16 infertile women with endometrial biopsy proven luteal phase defect (LPD) and 10 infertile women with a normal luteal phase. RESULTS: %FreeP, %CBG‐B, percent nonspecific protein‐bound P (%NSP), total P and total plasma estradiol (E 2 ) were measured during the normal ovulatory cycles of 5 women. The mean follicular phase %FreeP was found to be lower than in the luteal phase due to a decline in the late follicular phase. This decline correlated with the preovulatory rise in E 2 . The mean absolute concentration of free P (FreeP) rose significantly in the luteal phase, positively correlating with total P in both phases. Mean %CBG‐B and %NSP were unchanged throughout the cycle. P was lower in LPD vs. normal cycles, but %FreeP and %CBG‐B were not different. E 2 highly correlated with P but not with %FreeP and %CBG‐B. CONCLUSIONS: In normal cycles a small but significant decrease in %FreeP occurs in the late follicular phase and is associated with increasing E 2 . Changes in total P during the ovulatory cycle reflect changes in the concentration of bioactive P. There were no data to support an association of LPD with changes in the bioactive fraction of P.