What is the next step for a patient with mild anemia and no other abnormal indices?

Workup for Hemoglobin 12.4 g/dL with Normal Indices

The next step is to obtain a complete iron panel including serum ferritin, transferrin saturation, and consider checking vitamin B12 and folate levels to identify the underlying cause of anemia before initiating treatment. 1

Initial Laboratory Evaluation

For a patient with mild anemia (Hb 12.4 g/dL) and normal red cell indices, a systematic workup is essential:

• Check serum ferritin and transferrin saturation - These are the most efficient tests for diagnosing iron deficiency, even when MCV appears normal initially 2
• Obtain vitamin B12 and folate levels - Nutritional deficiencies account for approximately one-third of anemia cases and should be checked at least annually or when evaluating new anemia 1, 3
• Assess inflammatory markers - In the presence of inflammation, ferritin interpretation changes significantly; ferritin <100 μg/L with transferrin saturation <16% suggests iron deficiency in inflammatory states 1
• Review medication history - NSAIDs and other medications can contribute to occult blood loss 1

Clinical Context Matters

The approach differs based on patient demographics:

• Pre-menopausal women: Menstrual loss, menorrhagia, pregnancy, and breastfeeding are common causes, occurring in 5-10% of this population 1. However, women over age 45 should be investigated more thoroughly due to increasing incidence of gastrointestinal pathology 1
• Men and post-menopausal women: Any anemia warrants investigation for gastrointestinal blood loss as the primary concern 1

Avoid Common Pitfalls

Do not order faecal occult blood testing - This test is insensitive and non-specific, providing no diagnostic benefit 1

Do not routinely check liver function, renal function, or clotting studies unless the history suggests systemic disease 1

Do not assume normal indices exclude iron deficiency - Iron deficiency occurs in sequential stages, and hemoglobin/hematocrit decrease before MCV becomes abnormal 4

When to Proceed with Further Investigation

If iron studies confirm iron deficiency (ferritin <15 μg/L or <100 μg/L in inflammatory states with transferrin saturation <16%), proceed with:

• Upper GI endoscopy with small bowel biopsy for celiac disease screening 1
• Colonoscopy to evaluate for colonic sources of blood loss 1
• Gynecological evaluation in pre-menopausal women with suspected menorrhagia 1

Further invasive evaluation (enteroscopy, small bowel imaging) is not necessary unless the anemia becomes transfusion-dependent or there is visible blood loss 1

Monitoring Strategy

Once the workup is complete and treatment initiated:

• Monitor hemoglobin every 3 months if GFR <30 mL/min/1.73 m² or if chronic kidney disease is present 1
• Expect hemoglobin to rise by 2 g/dL after 3-4 weeks of appropriate iron therapy 1
• Continue iron supplementation for 3 months after correction to replenish body stores 1