Amenorrhea causes are indeed multiple. Pregnancy is the most frequent cause of amenorrhea but not the only one.
In fact when a woman does not have her regular periods and the pregnancy test are negative, both the woman and the doctor get prompted to seek for an explanation.The identification of the likely cause requires medical evaluation.
This page seeks to present the common amenorrhea causes for informational purposes only. It is not a replacement of medical evaluation.
It is obvious that the normal should be known before seeking to know the abnormal. If you are not yet familiar with the normal menstrual cycle, I suggest you get the ovulation cycle basics before reading ahead.
Two Types Of Amenorrhea
The absence of menstruation or amenorrhea is generally classified in two categories- primary and secondary, depending on the age of occurrence and clinical setting. These are primary and secondary amenorrhea. Primary amenorrhea concerns teenagers who have not had their menses by age 16.
Secondary amenorrhea is for women who have been having their periods before. Though pregnancy is the first cause, there are many other causes of secondary amenorrhea you should know. Some of these are also discussed below together with the causes of primary amenorrhea.
Understanding Amenorrhea Causes
The normal menstrual cycle requires normal hormonal levels and normal genital organs. If you are not yet familiar with the basics of the normal menstrual cycle,
Normal hormonal levels require the normal functioning of three structures: Hypothalamus, pituitary gland and the ovaries.
- Hypothalamus. This is a small structure in the brain. It controls other processes like hunger and body temperature. It produces the hormone Gonadotrophin releasing hormone (GnRH) which causes the pituitary gland to produce other menstruation hormones.
- Pituitary gland.
This is another small structure below the hypothalamus in the brain. In response to GnRH, it produces two hormones collectively called the gonadotrophins i.e. Follicle stimulating hormone (FSH) and Luteinizing hormone (LH). These two hormones act on the ovaries and amongst other effects cause them to produce other hormones.
- The ovaries. They produce estrogen and progesterone in response to FSH and LH, which affect the uterus and other organs.
- The hormonal axis.
For normal hormonal levels, all these three structures must be working normally. The hypothalamus sends chemical messages to the pituitary which sends messages to the ovaries which in its turn sends messages to uterus and other organs. This chain of structures producing hormones has been called the hypothalamus-pituitary-ovarian axis or HPO axis or simply the hormonal axis.
The Genital tract must be normal in the presence of normal hormones for menstrual flow. These structures include
- Uterus: The menstrual flow comes from the uterus. No uterus, no flow, even in the presence of normal hormones.
- The outflow tract.
When menstrual blood leaves the uterus, there must be a patent tract for it to flow out. The cervix, vagina and vaginal entry must be normal.
Any abnormality touching the three structures of the hormonal axis or the genital tract can lead to the absence of the menstrual flow. This will aid the understanding of the common causes of amenorrhea.
Common Amenorrhea Causes
Before medically evaluating amenorrhea, remember that there are these 3 physiologic and 1 drug-induced amenorrhea causes which should not raise any alarm. Physiologic means they are a part of the normal body functioning. These include
- Pregnancy. The usual first sign is absence of menses.
The process of breast feeding usually arrests menstrual flow. The breasts tell the uterus that there is still a young baby so no conception now! This is called lactational amenorrhea (lactational means breastfeeding).
- Menopause. This is the normal period of cessation of menses. No worries of amenorrhea after menopause!
- Birth control medications. They may be pills or injections containing the hormones which affect the menstrual cycle. Some may lead to an absence of menstruation.
As described above, the amenorrhea causes can be easily grouped under the body structure responsible for the abnormality. Both primary and secondary amenorrhea may result from any of these structures.For causes specific to secondary amenorrhea, please visit secondary amenorrhea.
Amongst these causes of amenorrhea are those collectively called functional causes. They are functional because they are due to functional perturbations without any organic abnormality in any of the structures.
- Excessive exercise especially amongst high level athletes
- Excessive stress. The cycle is sensitive to stress.
- Excessive weight gain or weight loss
- Malnutrition: Feeding habits could therefore have a bearing on the menstrual cycle.
- Eating disorders: Anorexia nervosa or bulimia
- Chronic diseases like tuberculosis and HIV.
- Psychiatric disorders like depression.
- Recreational drug use
- Drugs used in the treatment of psychiatric drugs. They are called psychotropic drugs.
common causes of amenorrhea, whether primary or secondary are given below by structure involved. The list is not comprehensive.
- Teratoma. An embryonic tumor made up of different tissues like nails, hairs etc
- Sarcoidosis. A chronic inflammatory disease whose cause is unknown. Often affects the lungs also.
- Kallmann syndrome. Deficiency of the gonadotrophins
- Craniopharyngioma (a brain tumor near the pituitary gland)
- Low body weight
- Pituitary tumors. Most common is Prolactinoma, a hormone that involved in breast milk secretion.
- Post-Partum Pituitary necrosis. Excessive bleeding after delivery causes death of pituitary gland cells.
- Autoimmune inflammation
- Ionizing radiation such as X-rays.
- Hemachromatoses. Excess iron in the body.
- Congenital genetic abnormalities. Eg Turner’s syndrome, pure gonadal dysgenesis and galatosemia. Often cause primary amenorrhea.
- Polycystic ovarian syndrome. Multiple cysts occur in the ovaries with metabolic abnormalities.
- Autoimmune diseases
- Chemotherapy or radiation toxicity
- Anovulation. Menstrual cycle without ovulation or release of the egg.
- Hyperandrogenism. Excess male hormones called androgens.
Genital tract abnormalities
- Imperforate hymen. A hymen with no passage of menstruall flow. Primary amenorrhea only.
- Vaginal septum. A membrane-like division closing the vaginal passage.
- Intrauterine adhesions. Opposite surfaces of the uterine walls attach to each other.
- Endometrial scarring( Asherman’s syndrome). Loss of endometrium and replacement with scar tissue. Excessive scrapping could cause this.
- Failed development of the vagina, cervix or the uterus( aplasia). Such women therefore are born without a uterus, cervix or vagina.
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