Lipoprotein and apolipoprotein levels in postmenopausal women on continuous oestrogen/ progestogen therapy

Levels of serum lipoproteins and apolipoproteins were monitored for 48 weeks in two groups of women taking part in a double-blind trial of continuous oestrogen/progestogen with and without oestriol. There were no differences between the effects of the two treatments on the substances measured. Triglycerides did not change and there was a transient fall in very low density lipoprotein cholesterol. Low density lipoprotein cholesterol fell over the first 24 weeks but rose thereafter to pretreatment levels. There was a decrease in high density lipoprotein (HDL) cholesterol due to a transient fall in HDL2 cholesterol and a gradual decrease in HDL3 cholesterol. Consequently, the only change in lipid levels present after 48 weeks was a decrease in HDL3 cholesterol, the clinical significance of which is uncertain. There was, however, an increase in apoprotein B levels and decreases in apoprotein AI and AII levels. These alterations in apoprotein levels may be unfavourable, since apoprotein B levels have been positively correlated and apoprotein AI and AII levels negatively correlated with coronary heart disease.