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Published by Floriva · Updated 2026-04-29 · How Floriva checks its guides

Menorrhagia (Heavy Periods): Causes, Diagnosis, and What to Track

Menorrhagia means clinically heavy periods. It affects up to 1 in 3 people who menstruate at some point. Here is how it is defined, what causes it, and what cycle tracking reveals.

Menorrhagia is defined as blood loss exceeding 80mL per cycle, or bleeding lasting more than 7 days with functional impairment. In practice that means soaking a pad or tampon every hour for several consecutive hours, passing clots larger than a quarter, or needing doubled protection. Common causes include uterine fibroids, adenomyosis, polyps, coagulation disorders, and thyroid dysfunction. Heavy periods have identifiable, treatable causes. 'That's just how my periods are' is not a complete evaluation.

Heavy periods are one of the most undertreated gynecological conditions. Period severity is often normalized as "just how it is," and heavy bleeding is difficult to measure objectively, which makes the experience easy to dismiss.

The clinical reality is that menorrhagia has identifiable causes in the majority of cases, and those causes are treatable. "It's just your heavy flow" is not a complete evaluation.

How to Define and Measure Heavy Bleeding

Clinical definition: Blood loss exceeding 80mL per cycle, or bleeding lasting more than 7 days with functional impairment (missing work, restricting activities).

The measurement problem: Most people can't measure 80mL directly. Here are practical proxies:

Volume indicators suggesting menorrhagia:

• Soaking a full-size pad or regular tampon completely in under an hour for 2 or more consecutive hours

• Filling a 30mL menstrual cup more than twice in a day on your heaviest days

• Passing clots larger than a quarter (25mm), indicating blood pooling faster than it can clot normally

• Needing to double up (pad + tampon simultaneously)

• Bleeding through clothing or bedding

• Waking in the night to change protection on multiple nights

A menstrual cup is the only consumer product that lets you measure volume directly. If you are unsure whether your flow is heavy, two cycles with a cup can give you actual volume data.

Common Causes

Uterine Fibroids (Leiomyomas)

Fibroids are benign smooth-muscle tumors of the uterine wall. Reports suggest they affect up to 70% of people with uteruses by age 50, though most cause no symptoms. Submucosal fibroids (projecting into the uterine cavity) cause the heaviest bleeding by increasing the surface area of endometrium and disrupting normal clotting.

Associated symptoms: Heavy periods, prolonged periods, pelvic pressure or fullness, frequent urination (from pressure on the bladder), and in large fibroids, visible abdominal enlargement.

Diagnosis: Pelvic ultrasound is the first-line imaging. Sonohysterography (saline infusion into the uterine cavity) provides better visualization of submucosal fibroids.

Adenomyosis

Endometrial tissue embedded in the uterine muscle. The uterus typically becomes enlarged, boggy (soft with a characteristic texture on examination), and tender. Each menstrual cycle causes this ectopic endometrial tissue to bleed into the uterine muscle, producing inflammation, enlargement, and heavier periods.

Associated symptoms: Very heavy, often painful periods; uterine tenderness on examination; possibly enlarged uterus; dysmenorrhea that's worsening over years.

Diagnosis: MRI is more accurate than ultrasound; definitive diagnosis historically required hysterectomy, but MRI has significantly improved non-invasive detection.

Endometrial Polyps

Benign outgrowths of endometrial tissue attached to the uterine lining by a stalk. Common (found in 10-24% of people with abnormal uterine bleeding), and most often benign, though rare malignant transformation occurs. Polyps cause irregular spotting between periods as well as heavy periods.

Diagnosis: Saline infusion sonography or hysteroscopy (direct visualization).

Coagulation Disorders

Von Willebrand disease (VWD) is found in approximately 13% of people with heavy menstrual bleeding, a higher rate than in the general population (approximately 1%). VWD is often missed because it is not included in standard heavy period workup at many practices.

Type 1 VWD (partial VWF deficiency, most common) typically presents as easy bruising, prolonged bleeding from cuts, and heavy periods. Type 2 and Type 3 are more severe.

Screening: PT, aPTT, von Willebrand factor antigen, and VWF activity should be part of the initial evaluation for heavy periods, especially in adolescents (first-onset heavy periods at menarche) and people with family history of bleeding disorders.

Thyroid Dysfunction

Both hypothyroidism (most common) and hyperthyroidism can cause heavy periods. Hypothyroidism affects coagulation, slows uterine contractility, and increases endometrial buildup. TSH should be checked in the initial heavy period evaluation.

Ovulatory Dysfunction

Anovulatory cycles (where no ovulation occurs) produce no progesterone, and without progesterone to stabilize the endometrium, the lining can build up excessively and shed heavily and irregularly. Common in PCOS, perimenopause, and the first few years of menstrual life.

Pattern: Heavy, often irregular bleeding rather than consistently heavy bleeding on schedule.

Endometrial Hyperplasia and Cancer

Endometrial hyperplasia (overgrowth of the uterine lining) causes heavy, irregular bleeding and can progress to endometrial cancer without treatment. Risk factors: prolonged exposure to estrogen without progesterone opposition (PCOS, obesity, perimenopausal anovulation), age over 40.

Endometrial biopsy is recommended for people over 45 with heavy bleeding and for those with risk factors at any age.

What Heavy Period Tracking Reveals

Documenting flow using a consistent scale creates the clinical data that makes evaluation easier:

For providers:

• Days with heaviest flow (day 1, 2, 3)

• Products used per day and how full/soaked

• Clot size and frequency

• Associated symptoms (cramps, pelvic pressure)

• Cycle length and predictability

Patterns that suggest specific causes:

• Very heavy + painful + worsening over years → adenomyosis or endometriosis

• Heavy + irregular + no predictable timing → ovulatory dysfunction, PCOS, perimenopause

• Heavy + feeling of pelvic fullness + frequent urination → fibroids

• Heavy from first period ever + easy bruising/prolonged wound bleeding → coagulation disorder

• Heavy + fatigue + weight gain + cold intolerance → hypothyroidism

Iron-Deficiency Anemia: The Hidden Consequence

Iron-deficiency anemia from menorrhagia is common and often unrecognized because its symptoms (fatigue, brain fog, exercise intolerance) are frequently attributed to other causes.

Testing: Ask for serum ferritin, not just hemoglobin. You can be significantly iron-depleted before becoming anemic. A ferritin level above 30 ng/mL is a common treatment target. Below 12 is clinically anemic.

Treatment: Oral iron (ferrous sulfate or ferrous bisglycinate; the latter tends to have fewer GI side effects) typically requires 3 to 6 months to replenish stores. Iron-rich foods alone are usually not enough when heavy bleeding is ongoing.

What This Means for Floriva Users

Log flow heaviness by cycle day using a 5-point scale or product count across multiple cycles. This creates documentation that helps providers evaluate severity and pattern. Noting when clots appear, which days are heaviest, and how flow has changed over time gives providers more to work with than a vague description of "really heavy." If flow is significantly affecting your daily life, this data supports getting a thorough evaluation.