Management of Mild Anemia with Low MCHC
The best course of action is to immediately check serum ferritin and transferrin saturation to confirm iron deficiency, then initiate oral iron supplementation (ferrous sulfate 200 mg three times daily) while investigating the underlying cause of iron loss. 1
Initial Diagnostic Workup
Your patient has mild anemia (Hb 11.4 g/dL, below the 12.0 g/dL threshold for women) with a low MCHC (30.7 g/dL), which strongly suggests iron deficiency anemia. 1, 2
Essential immediate laboratory tests:
- Serum ferritin is the most specific test for iron deficiency, with levels <30 μg/L confirming absolute iron deficiency 3, 1
- Transferrin saturation (TSAT) <20% indicates inadequate iron availability for erythropoiesis 1
- Red cell distribution width (RDW): elevated RDW (>14.0%) with low MCV strongly suggests iron deficiency anemia rather than thalassemia trait 3
- C-reactive protein (CRP) to assess for inflammation 4
- Serum creatinine and GFR to exclude chronic kidney disease as a contributing factor 1
The low MCHC (30.7 g/dL) is particularly significant because MCHC values are significantly lower in iron deficiency compared to other causes of microcytic anemia. 5
Treatment Initiation
Start oral iron supplementation immediately:
- Ferrous sulfate 200 mg (65 mg elemental iron) three times daily for at least three months 3
- Add ascorbic acid (vitamin C) to enhance iron absorption 3
- Alternative formulations (ferrous gluconate or ferrous fumarate) if gastrointestinal side effects occur 3
A good response is defined as hemoglobin rise ≥1 g/dL within 2 weeks, confirming iron deficiency. 3
Mandatory Investigation for Underlying Cause
This patient requires gastroenterology referral to rule out gastrointestinal malignancy, particularly if postmenopausal. 1, 2 Men and postmenopausal women with iron deficiency anemia should be evaluated with gastrointestinal endoscopy. 2
Additional workup to identify iron loss:
- Obtain tissue transglutaminase (tTG) antibody to screen for celiac disease, as approximately 5% of patients with iron deficiency anemia have celiac disease 1
- Detailed history regarding NSAID use, aspirin, dietary intake, menstrual blood loss (if premenopausal), and blood donation 1
- Stool for occult blood 4
Monitoring Strategy
Follow-up laboratory assessment:
- Expect hemoglobin increase of at least 2 g/dL within 4 weeks of starting oral iron 3
- Monitor hemoglobin concentration and red cell indices at three-monthly intervals for one year, then after a further year 3
- Continue oral iron for at least three months after correction of anemia to replenish iron stores 3
Critical Pitfalls to Avoid
Do not assume all low MCHC is iron deficiency: If ferritin is normal or elevated (>100 μg/L) despite low MCHC and TSAT <20%, this suggests anemia of chronic inflammation with functional iron deficiency. 1 In this scenario, consider intravenous iron rather than oral supplementation. 1
Do not overlook combined deficiencies: Iron deficiency can coexist with B12 or folate deficiency, so check these if response to iron is suboptimal. 3
Do not delay gastroenterology referral: Dual pathology (upper and lower GI bleeding sources) occurs in 1-10% of patients with iron deficiency. 1
Do not order bone marrow biopsy as a next step in straightforward microcytic anemia—reserve this for refractory cases after failed iron therapy or when the diagnosis remains unclear. 3
Check thyroid-stimulating hormone (TSH) to exclude hypothyroidism as a contributing factor to anemia. 1