VARIATIONS IN PLASMA-VOLUME AFFECT TOTAL AND LOW-DENSITY-LIPOPROTEIN CHOLESTEROL CONCENTRATIONS DURING THE MENSTRUAL-CYCLE

Serum lipids are known to vary during the menstrual cycle. To del:ermi ne if changes in plasma volume contribute to this effect, we determine d serum lipids, lipoproteins, and estimated changes in plasma volume i n 18 premenopausal women at the start of and at 5-day intervals after menstruation. Eleven men served as a comparison group. Changes in plas ma volume were estimated from changes in hemoglobin and hematocrit. To tal and low-density lipoprotein (LDL) cholesterol (mean +/- SD) increa sed 15 +/- 14 mg/dL (9% +/- 10%) and 11 +/- 13 (11% +/- 14%) within 10 days after the start of menstruation (P < .05) and then decreased tow ard baseline during the rest of the cycle. High density lipoprotein (H DL) cholesterol increased 3 mg/dL, or 5%, (P < .05) on days 10 and 15 after menstruation. Plasma volume decreased 4% +/- 9% (P < .06) 10 day s after the start of menstruation, and this maximum decrease in plasma volume coincided with peak increases in total, LDL, and HDL cholester ol. Except for an 8-mg/dL increase in LDL cholesterol at day 5, lipid changes were no longer significant after adjusting for changes in plas ma volume. We conclude that alterations in plasma volume account for a pproximately half of the increase in total and LDL cholesterol during the menstrual cycle. Copyright (C) 1995 by W.B. Saunders Company