What are the current Lexicomp guidelines for diagnosing and treating iron deficiency anemia?

Management of Iron Deficiency Anemia in Adults

Start with oral ferrous sulfate 200 mg twice daily as first-line treatment for iron deficiency anemia, continuing for 3 months after correction to replenish stores 1.

Diagnosis

Laboratory Criteria

• Low hemoglobin with microcytosis and hypochromia on peripheral smear
• Serum ferritin is the key diagnostic test:
  • Absolute iron deficiency: ferritin <30 μg/L in general population
  • In inflammatory states (CHF, IBD, CKD): ferritin <100 μg/L may still indicate iron deficiency 2
  • Transferrin saturation <20% supports diagnosis, especially when inflammation present 2

Critical Point on Screening

Faecal occult blood testing has no role in investigating IDA—it is insensitive and non-specific 1. Do not waste time or resources on this test.

Investigation Algorithm for Underlying Cause

All patients require:

1. Coeliac serology (tissue transglutaminase antibodies) - mandatory screening 1
2. Upper GI endoscopy (OGD) - to exclude gastric/duodenal pathology
3. Colonoscopy or CT colonography - to exclude colorectal pathology

Special populations:

• Premenopausal women <50 years: Only investigate GI tract if:

  • Age ≥50 years
  • Strong family history of colorectal cancer (two first-degree relatives OR one first-degree relative <50 years)
  • Upper GI symptoms warranting investigation
  • Persistent IDA despite iron supplementation and correction of menstrual losses 1

• Post-GI surgery patients: History of gastric/bariatric surgery does NOT preclude searching for other causes 2

If initial investigations normal and IDA persists/recurs:

• Test for Helicobacter pylori and eradicate if present 1
• Consider small bowel evaluation if indicated

Treatment

Oral Iron Therapy (First-Line)

Ferrous sulfate 200 mg twice daily is the standard, most cost-effective option 1.

Key treatment principles:

• Lower doses may be equally effective and better tolerated - consider dose reduction if side effects occur 1
• Alternative formulations (ferrous fumarate, ferrous gluconate) or suspensions may improve tolerance 1
• Continue for 3 months AFTER normalization to replenish iron stores 1
• Ascorbic acid 250-500 mg twice daily may enhance absorption, though evidence for clinical benefit is limited 1

Intravenous Iron Therapy

Indications for IV iron:

• Intolerance to oral iron
• Non-response to oral iron
• Clinical need for rapid correction
• Malabsorption (e.g., IBD with small bowel involvement)
• Chronic kidney disease on dialysis 2
• Chronic heart failure with iron deficiency (ferritin <100 μg/L OR transferrin saturation <20%) 2

IV Iron Options:

Preparation	Maximum Single Dose	Infusion Duration	Key Considerations
Ferric carboxymaltose	1000 mg	15 min	No anaphylaxis reported; preferred for convenience [1]
Iron sucrose	200 mg	10 min	Safe profile; multiple doses needed [1]
Iron dextran	20 mg/kg	6 hours	Single-dose correction possible BUT serious reactions 0.6-0.7%; fatalities reported [1]

Critical Safety Point: Anaphylaxis can occur with any IV iron preparation. Resuscitation facilities must be immediately available 1.

Special Population Considerations

Inflammatory Bowel Disease:

• Oral iron ≤100 mg elemental iron daily 2
• IV iron indicated for intolerance OR moderate-severe IDA (Hb <100 g/L) 2
• Monitor every 3 months for at least 1 year after correction, then periodically 2
• Recurrent IDA may indicate persistent intestinal inflammation despite clinical remission 2

Chronic Heart Failure:

• Screen all CHF patients: ferritin and transferrin saturation 2
• IV iron has prognostic benefit in CHF patients with iron deficiency (ferritin <100 μg/L and/or transferrin saturation <20%) 2
• Avoid oral iron in CHF - poorly absorbed due to gut edema, no prognostic benefit demonstrated 2

Chronic Kidney Disease:

• Oral iron for predialysis patients if tolerated 2
• IV iron required if oral not tolerated/ineffective OR dialysis commenced 2
• Coordinate with nephrology for erythropoietin management 2

Follow-Up Strategy

Once normalized:

• Monitor Hb and red cell indices at 3-month intervals for 1 year
• Recheck after 1 additional year
• Subsequently only if symptoms develop 1

If Hb/indices fall below normal:

• Resume oral iron supplementation
• Further investigation only needed if unable to maintain normal values with iron therapy 1

Reassuring data: Iron deficiency does not recur in most patients with negative initial investigations (normal OGD, coeliac serology, and colonoscopy) 1.

Common Pitfalls to Avoid

1. Do not rely on faecal occult blood testing - it adds no diagnostic value 1
2. Do not under-investigate elderly patients - anaemia of chronic disease can mimic IDA; confirm true iron deficiency before attributing to age/comorbidities 2
3. Do not stop oral iron too early - continue 3 months after correction to replenish stores 1
4. Do not use oral iron in CHF - use IV iron for prognostic benefit 2
5. Do not give IV iron without resuscitation facilities available - anaphylaxis risk exists with all preparations 1
6. Do not over-investigate premenopausal women <50 years without specific risk factors or persistent IDA 1