Is ordering iron panel studies and starting ferrous sulfate (iron supplement) 325mg daily appropriate for managing newly worsened normocytic anemia?

Management of Newly Worsened Normocytic Anemia in SNF Resident

Yes, ordering iron panel studies (ferritin, iron, TIBC/transferrin saturation) is appropriate before starting ferrous sulfate, but starting empiric ferrous sulfate 325 mg daily without confirming iron deficiency first is NOT recommended for normocytic anemia. 1

Why Iron Studies Must Come First

Your patient has normocytic anemia (MCV 82.1, stable from 80.5), not microcytic anemia. This is a critical distinction that changes the entire diagnostic approach:

• Normocytic anemia has multiple potential causes beyond iron deficiency, including anemia of chronic disease, early nutritional deficiencies (B12, folate), bone marrow disorders, chronic kidney disease, or occult blood loss 2
• Starting iron empirically without confirming deficiency can mask the true diagnosis and delay appropriate treatment 1
• The hemoglobin dropped significantly (from 12.9 to 10.6 g/dL) over a relatively short period, which warrants investigation rather than empiric treatment 1

The Correct Diagnostic Sequence

Step 1: Order comprehensive iron panel with next labs (not monthly routine labs—sooner if clinically indicated):

• Serum ferritin (most specific test for iron deficiency) 1
• Transferrin saturation (TSAT) 1, 3
• Total iron-binding capacity (TIBC) 1

Step 2: Add vitamin B12 and folate levels to your iron panel order, as these are common causes of normocytic anemia in elderly SNF residents 1

Step 3: Interpret results using these thresholds:

• Ferritin <30 μg/L indicates low iron stores 1
• Ferritin <45 μg/L provides optimal sensitivity/specificity for iron deficiency 1
• TSAT <20% indicates insufficient iron for red blood cell production 3
• However, ferritin can be falsely elevated by inflammation (common in SNF residents with chronic conditions), so TSAT becomes more important if ferritin is 30-150 μg/L 1

When to Start Ferrous Sulfate

Only start ferrous sulfate 325 mg daily (65 mg elemental iron) if: 4

• Ferritin is <45 μg/L, OR
• Ferritin is 45-150 μg/L with TSAT <20% 1, 3

Dosing considerations:

• Standard dose is ferrous sulfate 325 mg (65 mg elemental iron) once daily 4
• Taking on empty stomach improves absorption, but with food is acceptable if GI side effects occur 3
• Continue for at least 3 months after hemoglobin normalizes to replenish iron stores 1, 5

Expected Response and Monitoring

If iron deficiency is confirmed and treated:

• Hemoglobin should rise ≥1 g/dL (10 g/L) within 2-4 weeks 1, 3
• Recheck CBC at 3-4 weeks to confirm response 5
• If no response after 4 weeks, consider non-compliance, ongoing blood loss, malabsorption, or alternative diagnosis 1

Critical Pitfalls to Avoid

Do not assume normocytic anemia equals iron deficiency:

• Anemia of chronic disease is extremely common in SNF residents and can present with normocytic indices 2
• Early iron deficiency typically causes microcytosis (low MCV), not normocytic anemia 1
• Your patient's stable MCV (80.5 → 82.1) argues against progressive iron deficiency as the primary cause 1

Do not delay investigation of underlying cause:

• In elderly SNF residents, new anemia warrants evaluation for occult GI blood loss, especially with hemoglobin <10 g/dL 1
• Consider stool guaiac testing if not recently done 1
• Review medication list for drugs causing GI bleeding (NSAIDs, anticoagulants) or bone marrow suppression 2

Monitor for GI side effects that reduce adherence:

• Approximately 50% of patients experience constipation, nausea, or abdominal discomfort with oral iron 3
• Consider alternative formulations (ferrous gluconate, ferrous fumarate) if intolerance occurs 1, 5

Your Specific Plan Modification

Recommended approach:

1. Order iron panel (ferritin, iron, TIBC/TSAT), B12, and folate NOW rather than waiting for monthly routine labs 1
2. Hold ferrous sulfate until results confirm iron deficiency 1
3. Repeat CBC in 2-4 weeks to assess trend 1
4. If iron deficiency confirmed, start ferrous sulfate 325 mg daily and recheck hemoglobin at 3-4 weeks 5, 3, 4
5. Continue monitoring for occult blood loss or other causes 1

The patient's preserved renal function (eGFR 92) and stable electrolytes are reassuring, but the normocytic pattern demands proper workup before empiric iron therapy 6.