Causes of Menorrhagia

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Menorrhagia, the clinical term used to describe regular heavy menstrual bleeding, affects up to 30% of women between the ages of 12 - 51. Menorrhagia is defined as excessive blood loss during a woman’s period that interferes with her physical, emotional, social and material quality of life.

The average blood loss during a normal menstrual period is between 35-40 milliliters (mL) of blood; however, patients with menorrhagia will regularly experience menstrual blood loss that exceeds 80 mL. Despite this approximation, it is often difficult for clinicians to accurately quantify menstrual blood loss aside from estimating based on the number of tampons or pads used by the patient during their cycle.

While some women may have the condition from the onset of menses, others may develop heavier menstrual periods as they progress into the reproductive period. In some cases, women may continue to experience heavy bleeding after menopause.

Heavy Periods: Causes, Symptoms and Treatment

Causes of Menorrhagia

Dysfunctional Uterine Bleeding (DUB)

In approximately 40-60% of cases, the cause of menorrhagia is unknown, thereby terming this type of menorrhagia as dysfunctional uterine bleeding (DUB).  These patients have normal ovaries, uterus and hormone levels that allow for regular ovulation and menstrual cycles to occur each month.

DUB is commonly observed at the beginning of menses in adolescence and continues until the woman nears menopause. Some researchers believe DUB arises as a result of an imbalance in prostaglandin levels. The endometrium is more sensitive to certain prostaglandins, which are a class of inflammatory mediators that dilate the blood vessels of the uterus and cause excessive bleeding to occur.

Iatrogenic Causes

The term iatrogenic describes a condition that results from a medical examination or treatment. Common iatrogenic causes of menorrhagia include the use of systemic corticosteroid drugs, some chemotherapy agents and intrauterine contraceptive devices. The use of anticoagulant medications can also cause menorrhagia by altering natural blood clotting mechanisms.

Gynecological Diseases

The presence of polyps within the endometrial cavity, while benign, have been associated with causing an increase in blood loss during the menstrual cycle. Although this causal relationship is not fully understood, researchers have proposed that the combination of the abnormal microvasculature of endometrial polyps with a thickened endometrial lining can contribute to excessive blood loss. The presence of endometrial polyps may also prevent the endometrial lining from shedding completely during menstruation and ultimately contribute to menorrhagia. Other noncancerous growths within the female reproductive system that can also cause an increase in menstrual blood loss include leiomyomas, which are commonly referred to as uterine fibroids, and myomas.

Endometriosis, which is a disorder that causes the endometrium to grow outside of the uterus, has also been attributed with causing heavier and more painful periods.

Bleeding Disorders

Patients with underlying bleeding disorders, such as von Willebrand disease (VWD), are common in women suffering from menorrhagia. VWD occurs as a result of a deficient von Willebrand factor (VWF) that prevents the localization of platelets to the site of bleeding. As the most common bleeding disorder that affects approximately 1% of the global population, it has been estimated that up to 24% of women with menorrhagia have also been previously diagnosed with VWD. Several other types of platelet function disorders and coagulation deficiencies have also been associated with menorrhagia in women.

Endocrinological Diseases

An underactive thyroid, which is clinically referred to as hypothyroidism, is a condition that results from an inability of the thyroid gland to produce certain hormones. A causative association between hypothyroidism and menorrhagia has been supported in several research studies; however, the relationship between these two conditions remains controversial.

Other conditions that cause a hormone imbalance, such as polycystic ovary syndrome, obesity and insulin resistance, may also play a role in promoting menorrhagia. These types of hormone imbalance disorders can cause the endometrium to develop in excess prior to menstruation and therefore cause heavy blood loss when menstruation occurs.


  1. Hapangama, D. K., & Bulmer, J. N. (2016). Pathophysiology of Heavy Menstrual Bleeding. Women’s Health 12(1); 3-13.
  2. “Menstrual Disturbances”- African Journals Online
  3. “Hypothyroidism (underactive thyroid)” – Mayo Clinic
  4. Weeks, A. D. (2000). Menorrhagia and hypothyroidism. BMJ 320(7235). 649.
  5. “Menorrhagia (heavy menstrual bleeding” – Mayo Clinic
  6. “Endometriosis” – Mayo Clinic
  7. Byams, V. R., Anderson, B. L., Grant, A. M., Atrash, H., & Schulkin, J. (2012). Evaluation of bleeding disorders in women with menorrhagia: a survey of obstetrician-gynecologists. General Gynecology 207(4). DOI: 10.1016/j.ajog.2012.07.010.

Further Reading

Last Updated: Jan 21, 2019

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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