Oral 17 beta-estradiol and medroxyprogesterone acetate therapy in postmenopausal women increases HDL particle size

Menopause is accompanied by changes in lipoprotein particles that include a n increase in density of low density lipoproteins (LDL) and high density li poproteins (HDL) particles. The effect of 3 months of oral hormone replacem ent therapy (HRT) on lipoprotein particle size in postmenopausal women who were randomized to (I)estrogen replacement therapy (ERT) alone (either 17 b eta -estradiol (1 mg) or conjugated equine estrogens (CEE) (0.625 mg); (2) combination therapy (17 beta -estradiol plus medroxyprogesterone acetate (M PA) or CEE plus MPA): and (3) placebo were examined. Lipoprotein subclass c oncentrations and particle size were quantified by nuclear magnetic resonan ce spectroscopy (NMR). Combination HRT resulted in significant (P = 0.002) increases in HDL particle size as compared with those on placebo Formulatio ns or ERT alone. Women assigned to combined HRT had lower concentrations of smaller HDL particles after 3 months (P = 0.005) and higher concentrations of larger HDL particles (P = 0.02), whereas women assigned to ERT or place bo experienced non-significant changes. in summary. combined HRT increases HDL particle size by altering concentrations of the smallest and largest HD L subspecies. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.