Oligomenorrhea
Less frequent menstruation
From Wikipedia, the free encyclopedia
Oligomenorrhea is an abnormal bleeding pattern where menstrual bleeding occurs at intervals of greater than 35 days, with fewer than 9 periods in a year.[1] The period may be light in flow, short in duration or occur at irregular intervals.[1] Oligomenorrhea is common in adolescent females in the first few years following menarche.[2]
| Oligomenorrhea | |
|---|---|
| Other names | Oligomenorrhoea |
 | |
| Specialty | Gynecology |
Causes of oligomenorrhea range from chromosomal abnormalities to hypothalamic-pituitary conditions to hormonal imbalances. A common cause of oligomenorrhea is polycystic ovary syndrome (PCOS), a hormonal imbalance that results in menstrual irregularity.[3]
Menarche
Menarche is the first menstrual bleed in a female that has reached reproductive age. The median age at menarche is "12-13 years old across well-nourished populations in developed countries".[2] While the timing of pubertal development may vary among individuals, the order in which it occurs is fairly standard. Puberty in females begins with thelarche (breast development) followed by pubarche (growth of pubic and axillary hair) then followed, typically within 2-3 years of thelarche, by menarche. During adolescence, menstrual cycle intervals and durations may vary while the hypothalamic-pituitary-ovarian axis begins to mature.[2] Anovulation during the first few years of menstruation after menarche can cause variation in cycle intervals. A normal menstrual cycle typically lasts between 21-35 days.[3]
Causes
Premature ovarian insufficiency (POI), also known as primary ovarian insufficiency, is defined as "menopause before the age of 40" and presents as a "spectrum of declining ovarian function" resulting in reduced fertility due to a decrease in ovarian follicle number.[4][5] While majority of cases of POI are idiopathic, chromosomal abnormalities that result in the damage or loss of the X chromosome (i.e. Turner Syndrome, FMR1 pre-mutation carriers) have been described to reduce ovarian functionality and lead to premature ovarian insufficiency.[5] Other causes of POI include autoimmune disorders, chemotherapy, and pelvic radiation which cause rapid ovarian destruction and follicular depletion.[6] In those experiencing oligomenorrhea or menstrual irregularity, a diagnosis of POI can be confirmed with two elevated follicle-stimulating hormone levels (greater than 30-40 mIU/mL) at least 1 month apart.[6]
While primary amenorrhea is most common among those with Turner Syndrome, oligomenorrhea can be a symptom that these individuals experience.[7] Turner Syndrome is a chromosomal disorder where individuals have complete or partial loss of a single X chromosome, with the most common karyotype being 45,XO. Typical physical characteristics of Turner Syndrome include a webbed neck, low hairline, short stature, broad chest, and congenital heart defects. Irregular or absent menstrual cycles can occur with this condition as a result of streak ovaries or gonadal dysgenesis. It has been found that in individuals with Turner Syndrome "oocyte apoptosis is markedly accelerated in the early stage of fetal life," leading to low ovarian reserve and menstrual abnormalities.[8] Many of these individuals are often first diagnosed when evaluated for menstrual irregularities.[9]
Pituitary adenoma
Thyroid disease
PCOS
Functional hypothalamic amenorrhea
Medications
Oligomenorrhea can be a result of prolactinomas (adenomas of the anterior pituitary). It may be caused by thyrotoxicosis, hormonal changes in perimenopause, Prader–Willi syndrome, and Graves' disease.
Endurance exercises such as running or swimming can affect the reproductive physiology of female athletes. Female runners,[10][11] swimmers[12] and ballet dancers[13] either menstruate infrequently in comparison to non-athletic females of comparable age or exhibit amenorrhea. A more recent study shows that athletes competing in sports that emphasize thinness or a specific weight exhibit a higher rate of menstrual dysfunction than either athletes competing in sports with less focus on these or control subjects.[14]
Breastfeeding has been linked to irregularity of menstrual cycles due to hormones that delay ovulation.
People with polycystic ovary syndrome (PCOS) are also likely to have oligomenorrhea. PCOS is a condition in which excessive androgens (male sex hormones) are released by the ovaries. People with PCOS show menstrual irregularities that range from oligomenorrhea and amenorrhea, to very heavy, irregular periods. The condition affects about 6% of premenopausal females.
Eating disorders can result in oligomenorrhea. Although menstrual disorders are most strongly associated with anorexia nervosa, bulimia nervosa may also result in oligomenorrhea or amenorrhea. There is some controversy regarding the mechanism for the menstrual dysregulation, since amenorrhea may sometimes precede substantial weight loss in some anorexics.
Amenorrhea
Amenorrhea can be defined as a complete absence of menses. Amenorrhea can be divided into two categories: primary and secondary amenorrhea. Primary amenorrhea occurs when no menses occurs by the age of 15 with or without evidence of secondary sexual characteristics, or if no menses occur within three years of thelarche.[3] The causes of amenorrhea overlap with the causes of oligomenorrhea, with oligomenorrhea being a potential prodrome of amenorrhea.
See also
- Amenorrhea: absence of the menstrual period
- Menorrhagia: unusually heavy periods