Cholesterol Levels Fluctuate With Menstrual Cycle

Women's cholesterol levels vary throughout their menstrual cycle as their levels of estrogen rise and fall, a new study reveals. This means that to get a clear picture of a woman's cholesterol levels, doctors may need to take readings over several months before deciding whether the patient needs to have her levels lowered, the researchers noted. "Doctors who are looking at women high cholesterol have to take into account the phase of the menstrual cycle they are at when they take the measurement," said study co-author Enrique F. Schisterman, chief of the Epidemiology Branch at the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

"Practically, it's easier to recognize the beginning of a cycle," he said. "So if you do it consistently at the beginning of the cycle then you will get consistent measures over time." The report is published in the current online edition of the Journal of Clinical Endocrinology and Metabolism.For the study, Schisterman's group compared levels of estrogen with cholesterol and triglyceride levels in 259 healthy women, aged 18 to 44. Most of the women, had 14 or more measurements taken over two menstrual cycles. The women also charted the phases of their cycles using at-home fertility monitors that detect hormone levels indicating ovulation. Most of the women were physically active and did not smoke.

Only 5 percent had cholesterol levels higher than 200 mg/dL, which is borderline high-risk for heart disease. But, cholesterol levels among 19.7 percent of the women reached 200 mg/dL at least once. To make cholesterol readings more consistent and reliable, measurements should be taken at the same time each month for a couple of cycles, Schisterman added. "Practically, it's easier to recognize the beginning of a cycle," he said. "So if you do it consistently at the beginning of the cycle then you will get consistent measures over time."The report is published in the current online edition of the Journal of Clinical Endocrinology and Metabolism.