What are the recommendations for a patient with mild iron deficiency, slightly elevated creatinine levels, and normal folate and vitamin B12 levels?

Laboratory Interpretation and Management Recommendations

Primary Assessment: No Iron Deficiency Present

This patient does not have iron deficiency and does not require iron supplementation. The iron panel shows normal iron stores with ferritin at 246.1 ng/mL (well above the 100 ng/mL threshold), iron saturation at 23% (above the 20% cutoff), and hemoglobin at 13.5 g/dL (at the lower limit of normal for males) 1.

Key Laboratory Findings

Iron Status - Normal

• Ferritin 246.1 ng/mL: Indicates adequate iron stores, well above the recommended minimum of ≥100 ng/mL for maintaining erythropoiesis 1, 2
• Transferrin saturation 23%: Above the 20% threshold that defines adequate iron availability 1
• Serum iron 64.9 μg/dL: Within normal reference range 1
• UIBC 217 μg/dL: Slightly low but not clinically significant given normal ferritin and transferrin saturation 1

Hemoglobin - Borderline Low Normal

• Hemoglobin 13.5 g/dL: At the lower limit of normal for adult males (normal range 13.5-16.5 g/dL) 1
• Hematocrit 41.8%: Within normal range (41-50%) 1
• MCV 90.1 fL: Normocytic, ruling out iron deficiency anemia or B12/folate deficiency 1

Vitamin Status - Requires Attention

• Vitamin B12 228 pg/mL: Low-normal range (200-600 pg/mL reference) 1
  • Critical consideration: 5-10% of patients with B12 levels between 200-400 pg/mL may experience neuropsychiatric and hematologic abnormalities due to occult B12 deficiency 1
• Folate 8.71 ng/mL: Normal (>5.4 ng/mL is considered normal) 1

Renal Function - Mild Impairment

• Creatinine 1.2 mg/dL: Upper limit of normal 1
• GFR 61-74 mL/min/1.73m²: Stage 2-3a chronic kidney disease 1

Other Notable Findings

• Low anion gap 7.3 mmol/L: May reflect hypoalbuminemia or laboratory artifact 1
• Lymphopenia: Absolute lymphocytes 0.60 × 10³/μL (low) - warrants clinical correlation for chronic disease or immunosuppression 3

Management Recommendations

1. Do NOT Supplement Iron

• Iron supplementation is contraindicated with normal ferritin and transferrin saturation 2, 4
• Treatment with iron when ferritin is normal is potentially harmful and can lead to iron overload 4
• The slightly low UIBC is not clinically significant in the context of adequate iron stores 1

2. Address Borderline Vitamin B12

Given the B12 level of 228 pg/mL (in the 200-400 pg/mL range where occult deficiency can occur), consider:

• Measuring methylmalonic acid (MMA) and homocysteine to assess for functional B12 deficiency 5
• If MMA or homocysteine are elevated, initiate B12 supplementation 5
• Age consideration: If patient is >60 years old, B12 deficiency is more likely and empiric supplementation may be warranted 5
• Monitor B12 levels in 3-6 months if not supplementing 5

3. Monitor Renal Function

• The borderline GFR (61-74 mL/min/1.73m²) places this patient in CKD stage 2-3a 1
• If hemoglobin drops below 13.5 g/dL with worsening renal function, reassess iron parameters as CKD patients may develop functional iron deficiency requiring different targets (ferritin ≥100 ng/mL and transferrin saturation ≥20%) 1, 2

4. Investigate Lymphopenia

• Absolute lymphocyte count of 0.60 × 10³/μL is significantly low 3
• Evaluate for chronic inflammatory conditions, immunosuppression, or nutritional deficiencies that could contribute to borderline anemia 3

5. Follow-Up Laboratory Testing

• Repeat CBC in 3-6 months to monitor hemoglobin trend 1
• Repeat B12 level in 3-6 months if not supplementing, or sooner if neuropsychiatric symptoms develop 1, 5
• Monitor renal function (creatinine, GFR) every 6-12 months given borderline values 1

Common Pitfalls to Avoid

• Do not treat isolated low transferrin saturation when other iron parameters are normal - this leads to unnecessary iron supplementation and potential toxicity 4
• Do not ignore B12 levels in the 200-400 pg/mL range - up to 10% of patients in this range have functional deficiency 1, 5
• Do not assume normal MCV rules out B12 deficiency - combined deficiencies or early stages may present with normocytic anemia 5
• Do not overlook the significance of lymphopenia - this may indicate an underlying chronic condition contributing to the borderline anemia 3

Summary of Action Items

1. No iron supplementation needed 2, 4
2. Consider B12 supplementation or further testing (MMA, homocysteine) given borderline level 1, 5
3. Monitor CBC, B12, and renal function in 3-6 months 1
4. Investigate lymphopenia with clinical correlation 3
5. Reassess if hemoglobin drops below 13.5 g/dL or symptoms of anemia develop 1