RESUMO
The effect on protein and amino acid metabolism of combined oral contraceptives (OC) containing 150 micrograms of laevonorgestrel and 30 micrograms of ethinyl oestradiol was studied in a group of 34 healthy non-lactating women. This was compared to an identical study conducted in another group of 19 subjects who used IUCDs for contraception, and also in two other groups of subjects who were given an additional multivitamin preparation on a daily basis (29 subjects) and on the days when OC was not taken (29 subjects). Assessments were made prior to, and during the third week of the 4th, 7th, and the 13th cycles of OC treatment. Results indicated that the ceruloplasmin and retinol binding protein underwent significant increases with OC usage, while sex hormone binding globulin concentration, on the other hand, remained unaffected. At the same time, a significant reduction of several of the plasma amino acid and plasma albumin concentrations was observed, suggesting that the increase in the visceral and other types of protein concentrations previously noted was due to increased hepatic protein synthesis rather than increased breakdown or excretion as result of OC intake. Interesting biochemical alterations and metabolic effects previously observed may well be related to this altered synthesis and release of proteins and/or protein binders as well as induction of certain metabolic enzymes from the liver.
PIP: To assess the effects of combined oral contraceptive (OC) use on protein and amino acid metabolism, measurements were obtained from four groups of women: Group 1 (29 women who took OCs for 21 days followed by 7 days of multivitamin administration); Group 2 (29 women who took OCs and multivitamins concurrently for 21 days); Group 3 (34 women who took OCs and a placebo for 21 days); and Group 4 (19 IUD users). The OC used in this study contained 30 mcg of ethinyl estradiol and 150 mcg of levonorgestrel; 13 cycles were evaluated in the one-year study period. The fasting concentrations of ceruloplasmin and retinol binding protein increased by an average of 155% and 178%, respectively, above baseline in OC users but not in IUD controls. Fasting plasma concentrations of sex hormone binding globulin showed no changes over baseline in any of the four groups. Free amino acid concentrations were depressed in OC users by 13-33%, with the largest decreases occurring for tyrosine, glycine, ornithine, and proline. Finally, mean concentrations of alpha-1 and beta-globulins increased in OC users, while albumin and total protein decreased significantly. Overall, there was a trend toward increased hepatic protein synthesis with a resultant reduction in concentrations of plasma amino acids and albumin. Multivitamin supplementation did not alter any of these patterns.