Causes and Consequences of Irregular Menses

Introduction to Irregular Menses

Irregular menses are primarily caused by polycystic ovary syndrome (PCOS), functional hypothalamic amenorrhea, hyperprolactinemia, thyroid dysfunction, and primary ovarian insufficiency, according to the American College of Obstetricians and Gynecologists 1, 2

PCOS is one of the most common causes of irregular menstrual cycles, affecting approximately 4-6% of women in the general population, as reported by the European Society of Human Reproduction and Embryology 3
The prevalence of PCOS increases to 10-25% in women with temporal lobe epilepsy, according to the International League Against Epilepsy 3
Characterized by hyperandrogenic chronic anovulation with acceleration of pulsatile gonadotropin-releasing hormone (GnRH) secretion, as stated by the Endocrine Society 1

Accounts for approximately 20-35% of secondary amenorrhea cases, according to the American College of Obstetricians and Gynecologists 1
Main contributing factors include stress and increased stress sensitivity, vigorous exercise patterns, weight loss and low BMI, psychological disorders, and caloric restriction or energy deficit, as reported by the Academy of Nutrition and Dietetics 1, 2
In athletes, FHA is part of the female athlete triad or Relative Energy Deficiency in Sport (RED-S), according to the International Olympic Committee 4, 2

Accounts for approximately 20% of secondary amenorrhea cases, as stated by the American College of Obstetricians and Gynecologists 1
Causes include pituitary adenomas, medications, hypothyroidism, and chronic renal failure, according to the Endocrine Society 1, 2

Both hypothyroidism and hyperthyroidism can cause menstrual irregularities, as reported by the American Thyroid Association 1, 2
Altered thyroid hormone levels affect the hypothalamic-pituitary-ovarian axis, according to the Endocrine Society 2

Advanced liver disease can cause menstrual irregularities in >25% of women, as stated by the American Association for the Study of Liver Diseases 5
Altered estrogen metabolism and disruption of the hypothalamic-pituitary axis lead to anovulation and amenorrhea, according to the European Association for the Study of the Liver 5

Decreased bone mineral density and increased risk of osteoporosis, as reported by the National Osteoporosis Foundation 4, 2