An irregular period, or menstrual irregularity, is a collective term for any one of many potential abnormal variations in a woman's menstrual cycle. A woman's blood levels of the waxy substance called cholesterol naturally vary throughout the course of monthly menstruation. However, high cholesterol is not a known cause of an irregular period.
Menstrual Variations
Most women menstruate every 21 to 35 days and have a menstrual flow that lasts anywhere from four to seven days. If your menstruation or menstrual flow fall outside these ranges, you may have a menstrual irregularity. There is considerable variation, however, in the timing of both menstruation and menstrual flow, and some women naturally menstruate less than every 35 days or more frequently than every 21 days. In addition to these timing deviations, potential symptoms of an irregular period include not menstruating for more than 90 days, developing significant irregularities in comparison to your normal cycle and lack of menstruation past the age of 15.
Irregular Period Causes
The most common cause of irregular menstrual cycles is a condition called polycystic ovary syndrome, or PCOS, according to a study published in January 2011 in "The Journal of Clinical Endocrinology & Metabolism." Women with this syndrome have imbalances in their normal levels of sex hormones. MedlinePlus lists additional potential causes that include uterine fibroids, a thickening of the uterine lining called endometrial hyperplasia, use of an intrauterine device, use of medications such as anti-coagulants or steroids, pregnancy complications, changes in your use of birth control pills or estrogen, pelvic inflammatory disease, lupus, diabetes, cirrhosis, pituitary or thyroid disorders, stress, losing or gaining weight, and changes in your normal patterns of diet or exercise.
Cholesterol Variations
During the menstrual cycle, a woman's estrogen levels naturally rise as her egg cell approaches maturity and reach a peak just prior to the onset of ovulation. According to a study published in September 2010 in "The Journal of Clinical Endocrinology & Metabolism," blood levels of harmful low-density lipoprotein cholesterol and a blood-borne fat called triglyceride fall as estrogen levels rise. At the same time, blood levels of beneficial high-density lipoprotein cholesterol increase. Typically, LDL and triglyceride levels, along with a woman's total cholesterol levels, reach their lowest point just prior to menstruation. The average variation in the overall cholesterol levels of study participants over the course of menstruation was 19 percent.
Considerations
People with high cholesterol levels have increased chances of developing heart disease and experiencing a heart attack or stroke. Women with irregular menstrual cycles do appear to have some elevation in their risks for dying from heart disease, the authors of the 2011 study in "The Journal of Clinical Endocrinology & Metabolism" note. However, when a woman's body fat levels are taken into account, the added risk appears to be minimal. Doctors may need to consider natural variations in women's cholesterol levels when diagnosing high cholesterol, the authors of the 2010 study in "The Journal of Clinical Endocrinology & Metabolism" explain. Consult your doctor for more information on the causes of an irregular period and the potential consequences of high cholesterol levels.
References
- MedlinePlus: Menstrual Periods -- Heavy, Prolonged or Irregular
- U.S. Department of Health and Human Services - Office on Women's Health: Menstruation and the Menstrual Cycle Fact Sheet
- "The Journal of Clinical Endocrinology & Metabolism"; A Longitudinal Study of Serum Lipoproteins in Relation to Endogenous Reproductive Hormones During the Menstrual Cycle: Findings From the BioCycle Study; S. Mumford, et al.; September 2010
- National Institutes of Health - NIH News; Women's Cholesterol Levels Vary With Phase of Menstrual Cycle; August 2010
- "The Journal of Clinical Endocrinology & Metabolism"; Menstrual Irregularity and Cardiovascular Mortality; E. Wang, et al.; January 2011
- American Academy of Family Physicians - FamilyDoctor.org: Cholesterol; What Your Level Means
