Biochemical Basis for the Selection of Oral Contraceptives

Abstract

Many specific plasma proteins show dose-related changes when oral estrogens are administered. Large increases in concentration are seen in many important binding proteins, such as the sex hormone-binding globulin, transcortin, the retinol-binding protein, ceruloplasmin, and transferrin. A smaller group of plasma proteins are reduced in amount. These changes are related to altered rates of hepatic synthesis and secretion. As the overall effect of estrogen is one of increased protein synthesis, there is a reduction in the amount of plasma-free amino acids and in the pattern of distribution. Oral contraceptive (OC) users frequently show significant alterations in biochemical tests of vitamin status, at least some of which are related to alterations in plasma proteins. Other biochemical changes associated with OC use include a fasting hyperlipidemia, due mainly to increases in triglycerides, although there is often also a small increase in cholesterol. These changes are due primarily to increases in several lipoprotein fractions and are related mainly to the estrogen component. A deterioration in glucose tolerance occurs in many OC users and is probably induced by both estrogens and progestogens. There is evidence that certain clinical side effects of OCs, such as depression, are associated with specific biochemical changes.