Amenorrhea, the absence of menstruation, can happen for many different reasons. Firstly, there’s primary amenorrhea, in which a female has not had even her first cycle by age 16. Secondly, there’s secondary amenorrhea, where the female normally has a cycle, but then for some reason starts missing periods. It is important to remember that amenorrhea is not considered a disease; it is a symptom.
So what causes it?
In primary amenorrhea, the Mayo Clinic list five different causes as indicated below:
Chromosomal abnormalities - Certain chromosomal abnormalities can cause a premature depletion of the eggs and follicles involved in ovulation and menstruation.
Problems with the hypothalamus - Functional hypothalamic amenorrhea is a disorder of the hypothalamus — an area at the base of your brain that acts as a control center for your body and regulates your menstrual cycle. Excessive exercise, eating disorders, such as anorexia, and physical or psychological stress can all contribute to a disruption in the normal function of the hypothalamus. Less commonly, a tumor may prevent your hypothalamus from functioning normally.
Pituitary disease - The pituitary is another gland in the brain that's involved in regulating the menstrual cycle. A tumor or other invasive growth may disrupt the pituitary gland's ability to perform this function.
Lack of reproductive organs - Sometimes problems arise during fetal development that lead to a girl being born without some major part of her reproductive system, such as her uterus, cervix or vagina. Because her reproductive system didn't develop normally, she won't have menstrual cycles.
Structural abnormality of the vagina - An obstruction of the vagina may prevent visible menstrual bleeding. A membrane or wall may be present in the vagina that blocks the outflow of blood from the uterus and cervix.
In regards to secondary amenorrhea, the Mayo Clinic lists 12 reasons why a woman may start to miss periods:
Pregnancy - In women of reproductive age, pregnancy is the most common cause of amenorrhea. When a fertilized egg is implanted in the lining of your uterus, the lining remains to nourish the fetus and isn't shed as menstruation.
Contraceptives - Some women who take birth control pills may not have periods. When oral contraceptives are stopped, it may take three to six months to resume regular ovulation and menstruation. Contraceptives that are injected or implanted, such as Depo-Provera or Implanon, also may cause amenorrhea as can progesterone-containing intrauterine devices, such as Mirena.
Breast-feeding - Mothers who breast-feed often experience amenorrhea. Although ovulation may occur, menstruation may not. Pregnancy can result despite the lack of menstruation.
Stress - Mental stress can temporarily alter the functioning of your hypothalamus — an area of your brain that controls the hormones that regulate your menstrual cycle. Ovulation and menstruation may stop as a result. Regular menstrual periods usually resume after your stress decreases.
Medication - Certain medications can cause menstrual periods to stop. For example, antidepressants, antipsychotics, some chemotherapy drugs and oral corticosteroids can cause amenorrhea.
Hormonal imbalance - A common cause of amenorrhea or irregular periods is polycystic ovary syndrome (PCOS). This condition causes relatively high and sustained levels of estrogen and androgen, a male hormone, rather than the fluctuating levels seen in the normal menstrual cycle. This results in a decrease in the pituitary hormones that lead to ovulation and menstruation. PCOS is associated with obesity; amenorrhea or abnormal, often heavy, uterine bleeding; acne; and sometimes excess facial hair.
Low body weight - Excessively low body weight interrupts many hormonal functions in your body, potentially halting ovulation. Women who have an eating disorder, such as anorexia or bulimia, often stop having periods because of these abnormal hormonal changes.
Excessive exercise - Women who participate in sports that require rigorous training, such as ballet, long-distance running or gymnastics, may find their menstrual cycle interrupted. Several factors combine to contribute to the loss of periods in athletes, including low body fat, stress and high energy expenditure.
Thyroid malfunction - An underactive thyroid gland (hypothyroidism) commonly causes menstrual irregularities, including amenorrhea. Thyroid disorders can also cause an increase or decrease in the production of prolactin — a reproductive hormone generated by your pituitary gland. An altered prolactin level can affect your hypothalamus and disrupt your menstrual cycle.
Pituitary tumor - A noncancerous (benign) tumor in your pituitary gland (adenoma or prolactinoma) can cause an overproduction of prolactin. Excess prolactin can interfere with the regulation of menstruation. This type of tumor is treatable with medication, but on rare occasions, it requires surgery.
Uterine scarring - Asherman's syndrome, a condition in which scar tissue builds up in the lining of the uterus, can sometimes occur after uterine procedures, such as a dilation and curettage (D and C), cesarean section or treatment for uterine fibroids. Uterine scarring prevents the normal buildup and shedding of the uterine lining, which can result in very light menstrual bleeding or no periods at all.
Primary ovarian insufficiency - Menopause usually occurs between ages 45 and 55. In some women, the ovarian supply of eggs diminishes before age 40, a condition known as primary ovarian insufficiency. The lack of ovarian function associated with this condition decreases the amount of circulating estrogen in your body, which in turn thins your uterine lining (endometrium) and brings an end to your menstrual periods. Primary ovarian insufficiency, also referred to as premature menopause, may result from genetic factors or autoimmune disease, but often no cause can be found.
What can be done?
Usually, this symptom doesn’t stem from a fatal disease. It can be nerve-wracking to find the real cause for absent cycles because, as the Mayo Clinic puts it, it may involve a rather intricate array of hormonal problems. So, there will be tests, and maybe for some women, a lot of them.
However, once the root cause is found, treatment can begin. Your doctor can recommend anything from lifestyle changes so as to decrease weight, stress and even extreme physical activity. But in the case of a condition like PCOS, contraceptives are used in treatment. Or as in the case of thyroid and pituitary disorders, specialized medications are prescribed.
Resource: Mayo Clinic
Dita Faulkner is a freelance writer that enjoys addressing any medical issues. She also writes for a medical newsletter, entitled Renewal (not online), for those with rare disorders.