What are the next steps for an elderly male patient with mild anemia and a slightly elevated Prothrombin Time (PT), scheduled for a right knee replacement surgery?

Preoperative Management of Mild Anemia Before Knee Replacement

This patient requires comprehensive laboratory evaluation to identify the cause of anemia, with iron studies (serum ferritin and transferrin saturation), vitamin B12, folate, serum creatinine, and GFR as the immediate next steps. 1

Addressing the Slightly Elevated PT

The PT of 14.7 seconds (slightly elevated) with normal PTT and INR is not a contraindication to proceeding with surgery and does not require further workup in the absence of a bleeding history or active anticoagulation. 2 This isolated mild elevation rarely reflects clinically significant coagulopathy and should not delay the evaluation and management of the anemia, which is the more pressing concern. 2

Why This Anemia Matters

Preoperative anemia (Hb 11.9 g/dL in an elderly male, below the WHO threshold of 13 g/dL for men) is associated with increased perioperative morbidity, mortality, blood transfusion requirements, hospital length of stay, readmission rates, and postoperative complications. 1, 3, 4 The prevalence of preoperative anemia in patients awaiting total joint arthroplasty is approximately 22%, with iron deficiency being the most common and reversible cause (41% of anemic patients). 5, 4

Diagnostic Algorithm for Anemia Evaluation

Step 1: Assess Iron Status First

• Measure serum ferritin and transferrin saturation (TSAT) to distinguish between absolute iron deficiency, functional iron deficiency, and anemia of chronic disease. 1
• If ferritin <30 ng/mL and/or TSAT <20%: Absolute iron deficiency is present; consider gastroenterology referral to rule out gastrointestinal malignancy as a source of chronic blood loss. 1, 6
• If ferritin 30-100 ng/mL and/or TSAT <20%: Further evaluation needed to distinguish iron deficiency from inflammation/chronic disease. 1
• If ferritin >100 ng/mL and TSAT >20%: Iron deficiency is unlikely; proceed to evaluate other causes. 1

Step 2: Screen for Nutritional Deficiencies

• Measure vitamin B12 and folate levels to identify nutritional causes of anemia. 1, 6
• If deficient, initiate appropriate vitamin supplementation. 1

Step 3: Evaluate Renal Function

• Measure serum creatinine and calculate GFR to identify chronic kidney disease as a contributing factor. 1
• If creatinine is elevated or GFR is reduced, consider nephrology referral for management and potential erythropoiesis-stimulating agents (ESAs) with concurrent IV iron. 1, 6

Treatment Strategy Based on Findings

For Iron Deficiency Anemia

• If surgery is >6-8 weeks away: Oral iron therapy with 40-60 mg elemental iron daily in divided doses. 6, 7
• If surgery is within 2-3 weeks: Intravenous iron is preferred due to faster response and better absorption, particularly in the inflammatory perioperative setting. 6, 8
• Evidence shows preoperative iron treatment reduces transfusion risk by 39%, decreases transfusion units by 0.37 units, and shortens hospital stay by 2.08 days. 8

For Nutritional Deficiencies

• Treat vitamin B12 or folate deficiency with appropriate supplementation. 1, 6

For Anemia of Chronic Disease (Diagnosis of Exclusion)

• If no nutritional deficiencies or renal disease are identified, and chronic disease is present: Consider ESAs with concurrent iron supplementation. 1
• A therapeutic trial of iron confirms absolute iron deficiency; no response indicates anemia of chronic disease. 1

Timing Considerations

Ideally, hemoglobin should be checked 28 days before scheduled surgery to allow sufficient time for evaluation and treatment. 1, 6 Since this patient is already obtaining preoperative labs, the timeline for surgery should be assessed:

• If surgery is >4 weeks away: Complete diagnostic workup and initiate treatment to optimize hemoglobin to normal range (≥13 g/dL for men). 1, 6
• If surgery is <4 weeks away but >2 weeks: Expedite workup and consider IV iron if iron deficiency is confirmed. 6
• If surgery is imminent (<2 weeks): Consider delaying elective surgery if possible to allow time for anemia correction, as this will reduce perioperative complications. 1, 6

Critical Pitfalls to Avoid

• Do not proceed to surgery without investigating the cause of anemia, as this represents a missed opportunity to reduce perioperative morbidity and mortality. 1
• Do not delay surgery solely for isolated mild PT elevation without bleeding history or active anticoagulation, as this rarely reflects clinically significant coagulopathy. 2
• Do not assume anemia is "acceptable" at Hb 11.9 g/dL; the target should be within normal range (≥13 g/dL for men) to optimize outcomes. 1
• Do not use oral iron if surgery is within 2-3 weeks, as IV iron provides faster correction. 6

Expected Clinical Benefits of Treatment

Algorithm-led preoperative anemia screening and management reduces:

• Red blood cell transfusion rates (from 6% to 4.1%) 3
• Hospital readmission rates (from 4.5% to 2.3%) 3
• Critical care admission rates (from 1.3% to 0.5%) 3
• Length of stay (from 3.9 to 3.6 days) 3
• Overall costs (saving £263,000 per cohort) 3