What is the recommended management for a patient with anemia found on preoperative labs?

Management of Preoperative Anemia

No, you should not simply "resume iron" when anemia is found on preoperative labs—you must first perform laboratory testing to determine the cause of anemia, then treat based on the specific etiology and timing before surgery. 1

Immediate Actions Required

Order comprehensive laboratory evaluation to identify the underlying cause before initiating any treatment 1:

• Assess iron status: serum ferritin and transferrin saturation (TSAT) 1, 2
• Screen for nutritional deficiencies: vitamin B12 and folate levels 1
• Evaluate renal function: serum creatinine and glomerular filtration rate (GFR) to identify chronic kidney disease 1
• Look for chronic inflammatory disease: ferritin is an acute-phase reactant and may be falsely elevated with inflammation 1

Interpreting Iron Studies

The interpretation of iron studies differs based on inflammatory status 1, 2:

Without inflammation:

• Iron deficiency: ferritin <30 μg/L and/or TSAT <20% 2
• Adequate iron stores: ferritin >100 μg/L 1

With inflammation present:

• Iron deficiency: ferritin <100 μg/L with TSAT <20% 2
• Traditional ferritin threshold of 12 μg/L is inadequate in inflammatory states 1

Treatment Algorithm Based on Etiology and Timing

For Confirmed Iron Deficiency Anemia

Timing is critical for treatment selection 1, 2:

Surgery >6-8 weeks away:

• Oral iron therapy: 40-60 mg elemental iron daily in divided doses 1, 2
• Monitor response with repeat hemoglobin testing 1

Surgery within 2-3 weeks:

• Intravenous iron is preferred for moderate-to-severe anemia 2, 3
• Administer IV iron at least 10 days before surgery for optimal effect 2, 4
• Maximum hemoglobin increase typically occurs 2 weeks after IV iron administration 2, 4
• Hemoglobin increases steadily starting from 6 days post-administration, with optimal increases when given 10+ days before surgery 4

Specific IV iron dosing (ferric carboxymaltose) 5:

• Patients ≥50 kg: 750 mg IV in two doses separated by at least 7 days (total 1,500 mg per course) 5
• Patients <50 kg: 15 mg/kg IV in two doses separated by at least 7 days 5
• Alternative: single dose of 15 mg/kg (maximum 1,000 mg) in adults 5

For Non-Iron Deficiency Anemia

If iron deficiency is ruled out or corrected but anemia persists 1:

• Consider erythropoiesis-stimulating agents (ESAs) with concurrent IV iron 1
• This is a Grade 2A recommendation (moderate-quality evidence) 1

If vitamin B12 or folate deficiency identified:

• Treat with appropriate vitamin supplementation 1
• Grade 1C recommendation: nutritional deficiencies must be treated 1

If chronic kidney disease identified:

• Refer to nephrology for management 1
• May require ESA therapy in addition to iron 1

Critical Timing Considerations

Ideally, check hemoglobin 28 days (4 weeks) before scheduled surgery to allow sufficient time for evaluation and treatment 1, 2, 3:

• This timeframe permits erythropoiesis to occur after iron/vitamin supplementation 1
• Allows time for specialist referral if needed (gastroenterology for GI blood loss, nephrology for CKD) 1

Consider delaying elective surgery if newly diagnosed anemia is detected close to the surgical date 1:

• Target hemoglobin should be within normal WHO range before surgery 1
• Delay benefits patients by reducing transfusion exposure and improving outcomes 1

Special Clinical Scenarios

Absolute iron deficiency with GI source:

• Refer to gastroenterology to rule out gastrointestinal malignancy as source of chronic blood loss 1

Inflammatory bowel disease patients:

• IV iron is particularly indicated due to hepcidin-mediated inhibition of oral iron absorption 2

Functional iron deficiency (inflammation present):

• Consider IV iron therapy, especially with concomitant inflammation 2
• Oral iron may be ineffective due to iron sequestration 1

Common Pitfalls to Avoid

Do not assume all anemia is iron deficiency without laboratory confirmation 1:

• 33% of preoperative anemia is due to iron deficiency, but other causes include vitamin B12 deficiency (12.3%), folate deficiency (3%), chronic kidney disease, and chronic inflammatory disease 1

Do not rely on oral iron alone when:

• Surgery is scheduled within 2-3 weeks 2, 3
• Patient has inflammatory conditions affecting iron absorption 1, 2
• Patient has demonstrated intolerance or non-compliance with oral iron 1
• Ongoing blood losses exceed oral iron absorption capacity 1

Do not start treatment without identifying the cause:

• Unexplained anemia should be considered secondary to another process 1
• Failure to identify underlying pathology (malignancy, CKD) can lead to worse outcomes 1

Clinical Benefits of Proper Management

Treating preoperative anemia appropriately reduces 1, 2, 6:

• Perioperative morbidity and mortality 1
• Red blood cell transfusion requirements 6
• Hospital length of stay (reduced by 2.8 days in iron-supplemented IDA patients) 6
• Postoperative complications 2

Additionally, treatment improves 2:

• Postoperative physical rehabilitation 2
• Quality of life 7