What is the appropriate management for a patient with slightly elevated RDW (Red Cell Distribution Width) values, ranging from 14.00 to 16.10, over a period of five months, with the latest result being 14.00, and considering the patient's medical history and potential risk for anemia?

Management of Mildly Elevated RDW Trending Toward Normal

Your RDW values show a downward trend from 16.10 to 14.00 over five months, with the most recent value at the upper limit of normal (14.00), which suggests either resolving iron deficiency or a transient process that has corrected itself. 1, 2

Immediate Diagnostic Workup Required

You need iron studies now to determine if this represents resolving iron deficiency or another process:

• Serum ferritin is the single most powerful test for iron deficiency, with levels <30 μg/L confirming deficiency in the absence of inflammation, and <100 μg/L suggesting deficiency when inflammation is present 3, 1, 4
• Transferrin saturation <30% supports iron deficiency and is less affected by inflammation than ferritin 1, 4
• C-reactive protein (CRP) must be measured simultaneously because ferritin can be falsely elevated with inflammation, chronic disease, malignancy, or liver disease 1, 4
• Complete blood count with MCV and reticulocyte count to assess red cell size and bone marrow response 1, 4

Understanding Your RDW Pattern

Elevated RDW (>14.0%) indicates heterogeneous red blood cell populations, which strongly suggests iron deficiency rather than thalassemia or chronic disease. 2 Your peak value of 16.10 is consistent with iron deficiency, where both older normal-sized cells and newer microcytic cells coexist in circulation 2. The declining trend suggests either:

• Iron deficiency that is spontaneously improving (dietary changes, cessation of blood loss)
• Early stage of iron deficiency that was caught and is resolving
• Combined nutritional deficiencies that are correcting 1, 4

Critical Pitfall to Avoid

Never assume the problem has resolved simply because RDW is normalizing—you must confirm iron status with laboratory testing. 1 Iron deficiency in adult men and post-menopausal women typically indicates gastrointestinal blood loss or malignancy, which requires investigation regardless of whether the anemia appears to be improving 3, 1.

If Iron Deficiency Is Confirmed

Investigation for Blood Loss Source

All adult men and post-menopausal women with confirmed iron deficiency require both upper endoscopy with small bowel biopsy AND colonoscopy to exclude gastrointestinal malignancy, even with mild anemia. 3, 1 The severity of anemia does not correlate with the likelihood of serious underlying disease 1.

Specific sources to investigate:

• NSAID use (most common cause of occult GI bleeding) 3
• Colonic cancer or polyps 3
• Gastric cancer 3
• Angiodysplasia 3
• Coeliac disease (obtain small bowel biopsy during upper endoscopy) 3

Treatment Approach

• Initiate oral iron supplementation (ferrous sulfate 325 mg daily or equivalent elemental iron 65 mg daily) if iron deficiency is confirmed 2
• Recheck CBC in 4-6 weeks to confirm reticulocyte response and declining RDW 2
• Monitor iron status during treatment to assess response and detect potential iron overload 4

If Iron Studies Are Normal

Consider alternative diagnoses:

• Hemoglobinopathies such as thalassemia trait require hemoglobin electrophoresis, particularly in patients of Mediterranean, African, or Asian descent 3, 4
• Anemia of chronic disease requires assessment for underlying inflammatory conditions 1, 4
• Combined vitamin deficiencies (B12 or folate) can cause elevated RDW, though this is less common 5

Do not give iron supplementation to patients with thalassemia trait unless concurrent iron deficiency is documented by ferritin testing, as this can cause iron overload. 1

Special Considerations for Your Trending Values

The fact that your RDW peaked at 16.10 and has now normalized to 14.00 over five months suggests:

• If you made dietary changes or stopped taking NSAIDs, this could explain spontaneous improvement 3
• If you are a pre-menopausal woman, menstrual blood loss may have temporarily increased and then normalized 3
• If you have chronic kidney disease or inflammatory conditions, RDW can fluctuate with disease activity 6

However, you still require the full diagnostic workup outlined above because the initial elevation to 16.10 indicates that iron deficiency or another significant process was present. 1, 2