Relationship of the menstrual cycle and thyroid hormones to whole-body protein turnover in women.
Whole-body protein turnover was measured in eight women, using a single oral dose of 15N-glycine and urinary ammonia as the end product analysed. Energy and protein intakes were carefully controlled on the day of the measurement. Each subject was tested five or six times at weekly intervals. Four of the subjects were taking oral contraceptives, the other four were non-pill users. Values of whole-body protein turnover (flux) were within the range of previously reported data: 2.9-4.7 g/kg/d. Inter-individual variation was significantly greater than intra-individual variation. The latter ranged between 10 and 23 per cent. Protein turnover was significantly correlated with the serum T3/rT3 ratio (r = 0.845, P less than 0.01). No difference was found between pill users and non-pill users, nor between the luteal and the follicular phase of the menstrual cycle among non-pill users. These data suggest that the single-dose method with ammonia as the end product is suitable for human studies in clinical situations and that the phase of the menstrual cycle does not seem to be of critical importance when investigating menstruating women.
D000328:Adult; D000641:Ammonia / Q000652:urine; D005260:Female; D006801:Humans; D008597:Menstrual Cycle; D008875:Middle Aged; D009584:Nitrogen / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D013963:Thyroid Hormones / Q000097:blood*
D011506:Proteins; D013963:Thyroid Hormones; D000641:Ammonia; D009584:Nitrogen