What is the most likely cause of Iron Deficiency Anemia (IDA) in a 48-year-old woman with hypomenorrhea (light menstrual periods)?

Causes of Iron Deficiency Anemia in a 48-Year-Old Woman with Light Menstrual Periods

In a 48-year-old woman with iron deficiency anemia (IDA) and light menstrual periods, gastrointestinal pathology is the most likely cause and warrants prompt bidirectional endoscopy (upper and lower GI evaluation).

Diagnostic Approach

Initial Assessment

• Confirm IDA with laboratory tests:
  • Low serum ferritin (<30 μg/L is indicative of low iron stores)
  • Low hemoglobin
  • Low MCV (microcytosis)
  • Elevated RDW (red cell distribution width)

Key Considerations for This Patient

1. Age and Menstrual Status:

   • At 48 years old, this patient is approaching menopause
   • Light menstrual periods (hypomenorrhea) make menstrual blood loss an unlikely cause of IDA 1
   • This combination significantly increases the likelihood of GI pathology

2. Risk of GI Pathology:

   • Age, sex, hemoglobin concentration, and MCV are all independent predictors of GI cancer risk in IDA 2
   • Gastrointestinal blood loss is the most common cause of IDA in perimenopausal and postmenopausal women 3, 4

Most Likely Causes (In Order of Probability)

1. Gastrointestinal Pathology:

   • Colorectal cancer (higher risk with advancing age)
   • Gastric cancer
   • Peptic ulcer disease
   • Angiodysplasia
   • Inflammatory bowel disease
   • NSAID-induced mucosal damage 2, 1

2. Malabsorption Syndromes:

   • Celiac disease (found in 3-5% of IDA cases) 2, 4
   • Atrophic gastritis with or without H. pylori infection 2

3. Other Causes to Consider:

   • Chronic inflammatory conditions (may contribute to iron deficiency)
   • Medication effects (e.g., long-term PPI therapy)
   • Nutritional deficiencies (less likely as sole cause in this age group) 1

Recommended Investigation

1. First-Line Investigations:

   • Bidirectional endoscopy (upper GI endoscopy and colonoscopy) 2
   • Screening for celiac disease (serology or duodenal biopsy during endoscopy) 2
   • Urinalysis to exclude hematuria 2

2. If First-Line Investigations Are Negative:

   • Consider CT colonography if colonoscopy is contraindicated 2
   • Test for H. pylori and eradicate if present 2
   • Consider small bowel evaluation if symptoms suggest small bowel disease 1

Important Clinical Pearls

• Do not assume menstrual loss is the cause: Light menstrual periods make this an unlikely explanation for IDA in this patient 1

• Multiple causes may coexist: Even if one potential cause is identified, complete evaluation is still warranted 1

• Diagnostic pitfalls to avoid:

  • Accepting oesophagitis, erosions, or peptic ulcer disease as the sole cause of IDA without completing lower GI investigation 2
  • Assuming a dietary cause in the absence of a thorough GI evaluation 1
  • Dismissing mild anemia as insignificant 1

• Follow-up: Once the underlying cause is addressed and hemoglobin normalizes, monitor hemoglobin and red cell indices at 3-month intervals for the first year 1

The American Gastroenterological Association and British Society of Gastroenterology both emphasize that in perimenopausal women with IDA and light menstrual periods, gastrointestinal causes should be thoroughly investigated, as the risk of significant pathology including malignancy is substantially increased 2.