The menstrual cycle involves the maturation and release of an egg from the ovary, a thickening of the uterine lining, breast growth in preparation for pregnancy, then a shedding of the uterine lining during menstruation if pregnancy fails to occur. Phases of the menstrual cycle rely on several hormones throughout the body that signal to tissues in the female reproductive system. Abnormal menstrual cycles often occur as a result of hormone imbalances, and can develop as a result of an underlying disease or disorder.
Premature Ovarian Failure
Each month, an egg matures within a cyst in the ovaries, then matures and travels down the fallopian tube during ovulation. Premature ovarian failure, failure of the ovaries in women under the age of 40, prevents proper ovulation and subsequent menstruation. Patients suffering from ovarian failure begin to experience hormone imbalances, such as abnormally high levels of follicle-stimulating hormone and low levels of estrogen. In its early stages, ovarian failure leads to irregular menstruation, according to the Infertility Awareness Association of Canada. If left untreated, women with ovarian failure eventually stop menstruating and become infertile.
Tumor Growth
In some cases, irregular or absent menstruation may develop in response to tumor growth. Hormone levels play an essential role in regulating ovulation and menstruation, and hormone-secreting tumors can lead to hormone imbalances that throw off a normal menstrual cycle. One type of tumor that can lead to irregular menstruation is a prolactinoma, a tumor that secretes the hormone prolactin. Prolactinomas grow in the pituitary gland, a hormone-producing gland located at the base of the brain. In addition to irregular menstruation, patients with prolactinomas may experience a low sex drive or may begin producing breast milk, according to the National Endocrine and Metabolic Diseases Information Service. The tumor can be surgically removed to help restore normal hormone levels and allow for regular menstruation.
Endocrine Disorders
Irregular menstruation may reflect an underlying hormone imbalance due to an endocrine disorder. One of the most common endocrine disorder is polycystic ovarian syndrome, or PCOS, according to the University of Southern California. Along with irregular periods, women with PCOS are prone to obesity and diabetes, and typically have high testosterone levels leading to excess body hair growth. PCOS develops when eggs fail to properly mature and remain in a cyst on the ovary. Over time, the ovaries accumulate several cysts that disrupt ovarian functioning, leading to hormone imbalances. Following diagnosis, patients with PCOS can help control their disease with hormone therapy and by maintaining a healthy body weight.
