Management of Iron‑Deficiency Anemia in Premenopausal Women with Light Menstrual Bleeding

Diagnostic Approach

The British Society of Gastroenterology (BSG) recommends that light menstrual bleeding does not exclude gastrointestinal (GI) pathology; therefore, bidirectional endoscopy together with coeliac disease screening is essential in all such patients. 1
GI blood loss and malabsorption remain critical differential diagnoses even when menstrual flow is light; GI malignancy can present solely as iron‑deficiency anemia (IDA) without other symptoms, making urgent investigation mandatory. 1
BSG guidelines advise bidirectional endoscopy for every adult with unexplained IDA, irrespective of menstrual status, because dual pathology is found in 10–15 % of cases and upper‑GI endoscopy identifies a cause in 30–50 % of patients. 1

Immediate coeliac disease screening with tissue transglutaminase IgA antibody and total IgA level is recommended, as coeliac disease accounts for 3–5 % of IDA cases. 1
Urinalysis or urine microscopy should be performed to rule out renal‑tract bleeding as a source of iron loss. 1
In the absence of inflammation, a serum ferritin <30 ng/mL combined with a transferrin saturation <20 % confirms absolute iron deficiency. (American Journal of Hematology, 2024) 2

Gastroscopy and colonoscopy are required as first‑line investigations even when menstrual bleeding is light, because GI malignancies may present only as IDA. 1
If bidirectional endoscopy is negative and IDA recurs or fails to respond to iron therapy, capsule endoscopy is the preferred test for evaluating the small bowel. 1

Iron therapy should not be delayed while awaiting investigations unless colonoscopy can be performed within days; early treatment improves symptoms and does not compromise diagnostic accuracy. 1
A hemoglobin rise of ≥10 g/L within 2 weeks after starting therapy strongly suggests absolute iron deficiency, even when baseline iron studies are equivocal. 1
When oral iron is intolerable or ineffective after 4 weeks, transition to intravenous (IV) iron is advised; IV iron demonstrates superior efficacy in patients with malabsorption, ongoing blood loss, or oral‑iron intolerance. (American Journal of Hematology, 2024) 2

Complete blood count and iron studies (ferritin, transferrin saturation) should be repeated 4–8 weeks after completing iron replacement; testing within 4 weeks of IV iron is avoided because circulating iron interferes with assays. (American Journal of Hematology, 2024) 2
Target a ferritin level ≥50 ng/mL (in the absence of inflammation) to confirm adequate repletion. (American Journal of Hematology, 2024) 2
If hemoglobin does not rise after 4 weeks of oral iron, evaluate for ongoing blood loss, malabsorption, or functional iron deficiency (ferritin <100 ng/mL and transferrin saturation <20 %). (American Journal of Hematology, 2024; NCCN Guidelines 2012) [2][3]

Do not assume that light menstrual bleeding alone explains IDA without first excluding GI pathology; this can delay diagnosis of serious conditions such as malignancy. 1
Do not dismiss the need for GI investigation based on age or sex; both GI malignancy and coeliac disease occur in premenopausal women. 1
Do not stop iron therapy prematurely; continue until iron stores are repleted (ferritin ≥50 ng/mL), not merely until hemoglobin normalizes. (American Journal of Hematology, 2024) 2

A 30-year-old male with confirmed iron deficiency anemia requires urgent bidirectional endoscopy to exclude gastrointestinal malignancy and other pathology, along with coeliac disease screening and urinalysis, as recommended by the British Society of Gastroenterology 4, 5
Take a comprehensive history focusing on dietary patterns, medication use, gastrointestinal symptoms, family history, and blood loss, as suggested by the European Society of Gastrointestinal Endoscopy 6, 7, 8, 9
Perform urinalysis or urine microscopy to exclude renal tract bleeding as a source, as recommended by the American Gastroenterological Association 4, 5
Conduct coeliac disease screening, found in 3-5% of IDA cases, using serological testing with tissue transglutaminase antibody (IgA type) plus total IgA level, as suggested by the European Society of Gastrointestinal Endoscopy 4, 5, 6, 10
Review complete blood count, evaluating MCV, red cell distribution width (RDW), and blood film, as recommended by the British Society of Haematology 10, 11

Perform bidirectional endoscopy, including gastroscopy and colonoscopy, as first-line investigations in men with newly diagnosed IDA, as recommended by the American College of Gastroenterology 4, 5, 7
Upper GI endoscopy reveals a cause in 30-50% of patients, and dual pathology occurs in 10-15% of cases, as reported by the European Society of Gastrointestinal Endoscopy 9, 7
GI malignancy risk necessitates urgent investigation, as emphasized by the National Institute for Health and Care Excellence 4, 7

Capsule endoscopy is the preferred test for examining the small bowel, as recommended by the European Society of Gastrointestinal Endoscopy 4, 5, 7, 8
CT/MR enterography may be considered in those not suitable for capsule endoscopy, as suggested by the American Gastroenterological Association 4, 5, 8

Iron replacement therapy should not be deferred while awaiting investigations, unless colonoscopy is imminent, as recommended by the British Society of Gastroenterology 4, 5
Start with one tablet daily of ferrous sulphate, fumarate, or gluconate, and monitor for Hb response within 4 weeks, as suggested by the European Society of Gastrointestinal Endoscopy 4, 5, 7, 8