Abstract
CONTEXT: Menstrual cycle is considered the fifth vital sign among women. This study aimed to summarize the menstrual disturbances in different endocrine disorders. EVIDENCE ACQUISITION: In this narrative review, relevant studies (up to December 2019) were searched based on the MeSH keywords diabetes, polycystic ovary syndrome, Cushing's syndrome, thyroid dysfunction, hyperprolactinemia, menstrual cycle, uterine bleeding, and menstruation. Databases used for searching articles included Google Scholar, Scopus, PubMed, and Web of science for observational, experimental, and review studies. RESULTS: Endocrine disorders trigger the onset of menstrual disturbance across the reproductive lifespan of women. Endocrine glands (pituitary, thyroid, pancreas, adrenal, and ovaries) have a functional role in endocrine regulation of the menstrual cycle. According to available evidence, oligomenorrhea (cycles longer than 35 days) is the most common menstrual disturbance among endocrine disorders (thyrotoxicosis, hypothyroidism, polycystic ovary syndrome, Cushing's syndrome, and diabetes). Complex endocrine pathways play an essential role in a women's menstrual calendar. CONCLUSIONS: The menstrual cycle length and amount of bleeding can be indicative of endocrine disorders. Further studies are needed to identify the unknowns about the association between endocrine disorders and the menstrual cycle.