In this study involving 100 women, the metabolic changes seen with Norplant use were evaluated. Besides a significant increase in serum bilirubin, there were no other changes in liver function to suggest possible hepatocellular dysfunction at the end of five years. Even the raised mean levels of bilirubin remained within the normal clinical range for the local population. As regards lipid metabolism, total triglycerides, cholesterol and LDL-cholesterol were decreased through the five years of Norplant use. The HDL-cholesterol showed a significant increase in the first year; it then decreased over the years to its preinsertion level at the end of five years. As a result, the HDL-cholesterol/Total cholesterol - HDL-cholesterol showed a significant increase in the first year and then decreased to almost its preinsertion value at the end of five years. The findings appear to indicate Norplant use not to be contributory to cardiovascular risk. The use of Norplant was not associated with any significant effect on carbohydrate metabolism.
PIP: Health workers at the National University Hospital in Singapore drew blood samples from 100 women prior to insertion of Norplant and at month 6, 12, 24, 36, 48, and 60 to study the effects of Norplant on metabolic function. After 5 years of use, the bilirubin level was significantly higher (50%) than preinsertion levels (p.001). This was the only significant change in liver function. Further the mean level of bilirubin and other parameters of liver function were within the clinical range for all 100 women. High density lipoprotein (HDL) cholesterol level rose considerably the 1st year (p.001), but within 2 years it fell significantly below the mean preinsertion level (p.01). At the end of the study, however, it increased to almost its preinsertion level. The HDL cholesterol/total cholesterol - HDL cholesterol increased considerably the 1st year (p.001), but decreased over the remaining years to almost the preinsertion level (p.05). In fact, it always remained above 0.200--a level below this indicated an increased risk of acquiring coronary heart disease or progression of existing disease. No significant changes in carbohydrate metabolism occurred during the 5 years of the study. The results of the lipid and carbohydrate metabolic tests indicated that Norplant does not increase cardiovascular risk and may indeed protect against cardiovascular conditions. The researchers concluded that the evidence shows that Norplant can be used more often in the future.