What causes iron deficiency in middle-aged women?

Causes of Iron Deficiency in Middle-Aged Women

The primary causes of iron deficiency in middle-aged women are menstrual blood loss, pregnancy, poor dietary iron intake, and gastrointestinal conditions that cause blood loss or impair iron absorption. 1

Major Causes of Iron Deficiency

Menstrual Factors

• Heavy menstrual bleeding (≥80 mL/month) affects approximately 10% of women of childbearing age and is a leading cause of iron deficiency 1
• Regular monthly blood loss through normal menstruation contributes to ongoing iron depletion 1

Pregnancy and Reproductive Factors

• Pregnancy significantly increases iron requirements due to:
  • Expansion of blood volume by approximately 35% 1
  • Growth of the fetus, placenta, and maternal tissues 1
  • Increased iron demand (approximately 5.0 mg iron/day) in second and third trimesters 1
• High parity (multiple pregnancies) increases risk of iron deficiency 1
• Use of intrauterine devices can increase menstrual blood loss 1
• Conversely, oral contraceptive use is associated with decreased risk for iron deficiency 1

Dietary Factors

• Inadequate dietary iron intake is common among women of childbearing age 1
• Only about 25% of women aged 12-49 years meet the recommended dietary allowance for iron through diet alone 1
• Poor absorption of dietary iron due to dietary choices 1

Gastrointestinal Causes

• Occult or overt gastrointestinal bleeding 1, 2
• Malabsorption conditions:
  • Celiac disease (found in up to 4% of women with iron deficiency) 1
  • Atrophic gastritis 2
  • Post-bariatric surgery 2
  • Inflammatory bowel disease 2

Risk Assessment and Investigation

When to Suspect Underlying GI Pathology

Endoscopic investigation should be considered in middle-aged women with IDA if:

• Age over 50 years 1
• Non-menstruating status (e.g., post-hysterectomy) 1
• Presence of gastrointestinal symptoms or "red flag" symptoms 1
• Family history of gastrointestinal cancers 1
• Recurrent or persistent IDA disproportionate to other potential causes 1

Other Contributing Factors

• Chronic inflammatory conditions increase risk 2
• Medication use, particularly NSAIDs which can cause gastrointestinal bleeding 2
• Limited access to food (socioeconomic factors) 1

Diagnostic Approach

The minimum workup for suspected iron deficiency should include:

• Complete blood count with MCV
• Serum ferritin (primary diagnostic test)
• Transferrin saturation
• C-reactive protein (to assess for inflammation) 3

Common Pitfalls

• Failing to identify the underlying cause of iron deficiency
• Using inappropriate ferritin cutoffs in patients with inflammation
• Relying solely on hemoglobin for diagnosis 3
• Premature discontinuation of iron therapy before replenishing stores 3

Iron deficiency in middle-aged women is often multifactorial, with menstrual blood loss being the predominant cause in premenopausal women, while gastrointestinal blood loss becomes a more significant concern in older women and requires thorough investigation to rule out serious underlying conditions.