Lipid and biochemical changes after low-dose oral contraception

Abstract

A randomized double-blind study of the metabolic effects of 2 low-dose combined oral contraceptives was carried out in Singaporean women. The subjects comprised 58 women randomly allocated to two treatment groups (29 each): norethisterone 1 mg/ethinyl estradiol 35 μg (NET/EE) or levonorgestrel 150 μg/ethinyl estradiol 30 μg (LNG/EE) and a control group of 23 women using intra-uterine devices (IUD). Blood samples were taken on admission and at 3 and 12 months after pills or insertion of IUDs.

This randomized double-blind study of the metabolic effects of two low-dose oral contraceptives was conducted in 58 randomly selected Singaporean women. Study subjects were divided into two treatment groups: 1) norethisterone 1 mg/ethinyl estradiol 35 mcg (NET/EE) or levonorgestrel 150 mcg/ethinyl estradiol 30 mcg (LNG/EE) were given to 35 women; 2) a control group of 23 women using IUDs. Blood samples were taken on admission and at 3 and 12 months after pills or insertion of IUDs. Findings demonstrate a significant decrease in mean fasting glucose and in 2-hour glucose loading, while triglycerides were increased throughout the treatment period in the NET/EE group. The LNG/EE group only showed significant suppression of the 2-hour glucose loading at 12 months and low-density lipoprotein/high-density lipoprotein (LDL/HDL) cholesterol was significantly reduced by 12 months. Both groups had no change in hemoglobin, hematocrit and total protein levels, but alkaline phosphatase, bilirubin and aspartate transaminase (SGOT) were decreased. Decreased albumin was observed in the NET/EE group, but not in the LNG/EE group. Changes in total HDL and LDL cholesterol and SGOT were not significantly different in the treatment group compared to the IUD group, except for the 2-hour glucose loading. There was no increase in the number of abnormal parameters after treatment. On the contrary, there was a reduction of abnormal values in most liver function parameters. Thus, except for glucose intolerance, the observed changes in metabolic parameters may not be of any clinical significance.