Amenorrhea is the absence of menstrual bleeding. Amenorrhea is a normal feature in :
- postmenopausal females.
In females of reproductive age, diagnosing amenorrhea is a matter of first determining whether pregnancy is the etiology. In the absence of pregnancy, the challenge is to determine the exact cause of absent menses. This article reviews the physiologic aspects of menstruation and presents an approach for ascertaining the etiology of amenorrhea. Only the main components of amenorrhea are highlighted. Many minor components of physiology are important but are beyond the scope of this article.
The menstrual cycle can be divided into 3 physiologic phases: follicular, ovulatory, and luteal. Each phase has a distinct hormonal secretory milieu. When one diagnoses the disease processes responsible for amenorrhea, consideration of the target organs of these reproductive hormones (hypothalamus, pituitary, ovary, uterus) is helpful.
Primary and Secondary AmenorrheaPrimary amenorrhea is defined either as absence of menses by age 14 years with the absence of growth or development of secondary sexual characteristics (eg, breast development) or as absence of menses by age 16 years with normal development of secondary sexual characteristics.
Secondary amenorrhea is defined as the cessation of menstruation for at least 6 months or for at least 3 of the previous 3 cycle intervals. Because only 3 diagnoses are unique to primary amenorrhea and never cause secondary amenorrhea, differentiating primary from secondary amenorrhea does little to enhance the clinician's understanding of the etiology.
The causes of amenorrhea are listed below. Organize clinical evaluation on the basis of sexual development and basic developmental physiology. With such a vast differential diagnosis, one way to organize and memorize the causes of amenorrhea can be in its relationships with generalized pubertal delay, normal pubertal development, or abnormalities of the genital tract.
- Failure of the ovaries (female sex organs that hold eggs).
- Problems in the central nervous system (brain and spinal cord) or the pituitary gland (a gland in the brain that makes hormones involved in menstruation).
- Poorly formed reproductive organs.
- Breast feeding
- Stopping the use of birth control
- Some birth control methods, such as Depo-Provera
- Poor nutrition
- Certain drugs
- Extreme weight loss
- Ongoing illness
- Sudden weight gain or being very overweight (obesity)
- Hormonal imbalance due to polycystic ovarian syndrome (PCOS)
- Thyroid gland disorders
- Tumors on the ovaries or brain (rare)