Combination-type oral contraceptives are potent systemic steroids that may cause many detectable alterations in metabolic function, such as increases in binding globulins, bromsulphalein retention, triglycerides and total phospholipids, and a decrease in glucose tolerance. Thus, the benefits of birth control pills must be weighed carefully against the added risks in patients with diabetes, cardiovascular disease, or liver disease. The pill modestly increases HDL cholesterol levels, but should have no direct effect on hemoglobin concentration. In fact, since bleeding volume is generally diminished in birth control pill users, hemoglobin concentration often increases in these patients.