THE EFFECT OF PERCUTANEOUS ESTROGEN REPLACEMENT THERAPY ON LP(A) AND OTHER LIPOPROTEINS

Objectives: To determine the effect of percutaneous oestrogen replacem ent therapy on lipoprotein (a) and other plasma lipoproteins. Methods: Open longitudinal prospective study conducted at the hormone replacem ent clinic of the Prince of Wales Hospital, New Territories, Hong Kong . Thirty women who had undergone a total abdominal hysterectomy and bi lateral salpingo-oophorectomy for benign gynaecological conditions wer e treated with 1.5 mg of percutaneous 17 beta-oestradiol gel applied d aily for a period of 12 consecutive months. Measurements of plasma lip oproteins were made before the commencement of treatment and repeated at 6- and 12-month intervals. Results: There was a significant reducti on in the concentrations of Lp(a) during the first 6 months of treatme nt, with median values falling from 7.87 mg dL(-1) to 6.16 mg dL(-1) ( P = 0.004, 0-6 months). During the second 6 months, the median concent ration increased to 9.38 mg dL(-1), (P=0.072, 6-12 months), which did not significantly differ from the baseline level (P = 0.545, 0-12 mont hs). Significant reductions in the concentrations of apoprotein A-I (a pe A-I), apoprotein B (apo B), high density lipoprotein cholesterol (H DL-C), and HDL(3)-C were also present after 6 months (P = 0.043, 0.049 , 0.028, 0.013, respectively), but there were no differences between t he baseline values of these lipoproteins and those at the completion o f the study (P = 0.948, 0.244, 0.839, 0.117 respectively). Drug compli ance was maintained throughout the study, with similar mean oestradiol concentrations at 6 and 12 months. Conclusions: The percutaneous admi nistration of 17 beta-oestradiol has variable short term effects on pl asma lipoproteins which are not maintained over a longer duration of t reatment, By avoiding the 'first pass' effect on the liver, this metho d of delivery does not appear to produce the sustained changes in lipo proteins seen with oral treatment.