What causes irregular menses?

Causes of Irregular Menses

Irregular menses are primarily caused by polycystic ovary syndrome (PCOS), functional hypothalamic amenorrhea, hyperprolactinemia, thyroid dysfunction, and primary ovarian insufficiency. 1, 2

Polycystic Ovary Syndrome (PCOS)

• PCOS is one of the most common causes of irregular menstrual cycles, affecting approximately 4-6% of women in the general population 3
• The prevalence increases to 10-25% in women with temporal lobe epilepsy 3
• Characterized by hyperandrogenic chronic anovulation with:
  • Acceleration of pulsatile gonadotropin-releasing hormone (GnRH) secretion
  • Insulin resistance and hyperinsulinemia
  • Hypersecretion of luteinizing hormone (LH)
  • LH:FSH ratio >2 1
  • Polycystic ovarian morphology on ultrasound 1
• Laboratory findings typically show elevated testosterone levels and increased LH:FSH ratio 3, 1

Functional Hypothalamic Amenorrhea (FHA)

• Accounts for approximately 20-35% of secondary amenorrhea cases 1
• Characterized by chronic anovulation without identifiable organic causes 1
• Main contributing factors include:
  • Stress and increased stress sensitivity
  • Vigorous exercise patterns (common in athletes)
  • Weight loss and low BMI
  • Psychological disorders
  • Caloric restriction or energy deficit 1, 2
• Laboratory findings include low/normal FSH and LH levels 1
• In athletes, this is part of the female athlete triad or Relative Energy Deficiency in Sport (RED-S) 3, 2

Hyperprolactinemia

• Accounts for approximately 20% of secondary amenorrhea cases 1
• May present with galactorrhea and irregular menses 1
• Causes include:
  • Pituitary adenomas
  • Medications (antipsychotics, antidepressants)
  • Hypothyroidism
  • Chronic renal failure 1
• Laboratory findings include elevated serum prolactin levels 1

Thyroid Dysfunction

• Both hypothyroidism and hyperthyroidism can cause menstrual irregularities 1, 2
• Altered thyroid hormone levels affect the hypothalamic-pituitary-ovarian axis 2
• Laboratory findings include abnormal TSH levels 1

Primary Ovarian Insufficiency (POI)

• Characterized by elevated FSH and LH levels 1
• Can occur due to:
  • Genetic factors
  • Autoimmune disorders
  • Iatrogenic causes (chemotherapy, radiation)
  • Infections 1, 4

Chronic Liver Disease

• Advanced liver disease can cause menstrual irregularities in >25% of women 3
• Altered estrogen metabolism and disruption of the hypothalamic-pituitary axis lead to anovulation and amenorrhea 3
• Nearly 75% of premenopausal women awaiting liver transplant experience amenorrhea 3

Other Causes

• Autoimmune disorders may contribute to PCOS and irregular menses 5
• Epilepsy can directly affect the hypothalamic-pituitary axis 3
• Excessive alcohol intake affects the hypothalamic-pituitary axis or directly affects ovarian function 3
• Medications (e.g., antipsychotics, hormonal contraceptives) 4
• Structural abnormalities of the reproductive tract 4

Special Entity: FHA-PCOM

• Affects approximately 40-47% of women with FHA 1
• Features characteristics of both FHA and polycystic ovarian morphology 1
• Can be misdiagnosed as PCOS as they fulfill Rotterdam criteria 1
• Differentiation based on typical FHA triggers, negative progestin challenge, and lower LH levels 1

Health Implications of Irregular Menses

• Increased risk of endometrial hyperplasia and cancer due to unopposed estrogen 6
• Decreased bone mineral density and increased risk of osteoporosis 3, 2
• Associated with metabolic syndrome, coronary heart disease, and type 2 diabetes 7
• Fertility issues and potential pregnancy complications 7, 4
• Psychological impact affecting quality of life 7

Irregular menstruation should be considered an important health indicator requiring thorough evaluation and appropriate management to prevent long-term health consequences 7.