Lipoprotein and apoprotein levels in postmenopausal women during treatment with norethisterone.

Lipoprotein and apolipoprotein levels were monitored in 21 postmenopausal women during 6 months' treatment with norethisterone. There was no significant change in low density lipoprotein (LDL) cholesterol but apoprotein B levels rose significantly (p less than 0.001) thus increasing the apoprotein:cholesterol ratio in LDL. High density lipoprotein (HDL) cholesterol levels decreased significantly (p less than 0.001) in the first two months and did not change significantly thereafter. The HDL2 subfraction was reduced to a greater extent than the HDL3 subfraction. Apoprotein AI and AII levels were both reduced as was the apoprotein AI:AII ratio. The ratios of apoproteins AI and AII to HDL cholesterol were increased. We conclude that norethisterone has an adverse effect on the important risk factors for cardiovascular disease.