[Has oligomenorrhea a pathological meaning? The importance of this symptom in internal medicine]

Oligomenorrhea, defined as a menstrual cycle lasting 36 to 90 days, can be a normal condition in the first years after the menarche. When it persists or appears after a period of normal menstrual cycles, an underlying illness must be sought.

To assess ovulation and causes of anovulatory cycles in women with oligomenorrhea, compared with causes of secondary amenorrhea.

One hundred one women of less the 35 years old, presenting with oligomenorrhea persisting 5 years after menarche or lasting more than two years after a period of normal menstrual cycles, were studied. Ovulation was studied measuring serial plasma progesterone during normal or induced (with intramuscular progesterone) menstrual cycles.

Eighty nine percent of women had anovulatory oligomenorrhea. The main causes were polycystic ovarian disease in 51% and hypothalamic dysfunction in 31%. Thirty percent of women with secondary amenorrhea had polycystic ovarian disease and 14% had hyperprolactinemia. Women older than 20 years old or with more than 10 years of gynecological age had a higher frequency of polycystic ovarian disease and a lower prevalence of hypothalamic dysfunction.

There is a high frequency of anovulatory oligomenorrheas. Therefore, this symptom deserves a thorough endocrinological assessment to uncover underlying diseases. Special attention must be paid to polycystic ovary syndrome, due to its importance in internal medicine as a risk factor for myocardial infarction, high blood pressure, and type 2 diabetes mellitus.