Diagnosis: Mild Hypochromic Anemia with Likely Iron Deficiency
The isolated low MCH (26.2 pg) and MCHC (29.6 g/dL) with otherwise normal CBC parameters most likely represents early or mild iron deficiency anemia, even though hemoglobin remains within normal range. 1, 2
Key Laboratory Findings
Your CBC shows:
- Normal hemoglobin (13.4 g/dL) and hematocrit (45.3%) 1
- Low MCH (26.2 pg; reference 27.0-34.0 pg) indicating reduced hemoglobin content per red cell 3, 4
- Low MCHC (29.6 g/dL; reference 31.0-37.0 g/dL) indicating reduced hemoglobin concentration within red cells 3, 4
- Normal MCV (88.6 fL) suggesting normocytic red cells 1
- Normal RBC count, platelets, and white cell parameters 1
Clinical Interpretation
This pattern represents hypochromia (reduced hemoglobin concentration) without microcytosis, which is characteristic of early iron deficiency before MCV drops. 3, 4
Why Iron Deficiency is Most Likely:
- MCH and MCHC typically decrease before MCV falls in progressive iron deficiency 3, 4
- The combination of low MCH and MCHC with normal MCV has 68-93% diagnostic accuracy for iron deficiency in young adults 4
- MCHC values below 31 g/dL are significantly associated with iron deficiency 3, 5
Important Caveat:
Normal MCH and MCHC do NOT exclude iron deficiency - these parameters have only 50% specificity even when optimized for 90% sensitivity 4. Therefore, serum ferritin measurement is essential for definitive diagnosis. 1
Recommended Diagnostic Workup
Obtain serum ferritin immediately - this is the most powerful test for iron deficiency: 1
- Ferritin <12 μg/dL is diagnostic of iron deficiency 1
- Ferritin <15 μg/dL strongly suggests iron deficiency 4
- Ferritin 12-100 μg/dL requires additional evaluation 1
If ferritin is equivocal (12-100 μg/dL), measure: 1, 2
- Transferrin saturation (TSAT) - values <30% support iron deficiency 1
- C-reactive protein (CRP) - elevated CRP can falsely elevate ferritin in inflammatory states 2
Consider reticulocyte count: 2
- Normal/low reticulocyte count with iron deficiency indicates inadequate bone marrow response 2
- Elevated reticulocyte count would suggest hemolysis or recent blood loss 2
Differential Diagnosis to Consider
While iron deficiency is most likely, also evaluate for: 2
Thalassemia trait: 2
- Typically shows microcytosis (MCV <80 fL) disproportionate to anemia
- Your normal MCV makes this less likely
- Consider hemoglobin electrophoresis if family history or ethnicity suggests risk
Anemia of chronic disease: 2
- Can present with low MCHC
- Usually shows normal or elevated ferritin with low TSAT
- Requires evaluation for underlying inflammatory conditions, infections, or malignancy
Sideroblastic anemia: 2
- Rare hereditary disorder
- Shows normal or elevated iron stores despite hypochromia
- Requires bone marrow examination for ringed sideroblasts
Clinical Pitfalls to Avoid
Do not assume normal hemoglobin excludes clinically significant iron deficiency - mild anemia (Hb 12-13 g/dL in women, 13-14 g/dL in men) warrants investigation if MCH/MCHC are low 1, 2
Beware of spurious MCHC elevation from cold agglutinins or lipemia, though your MCHC is low, not elevated 6
In inflammatory states, ferritin may be falsely elevated - use TSAT and CRP to identify "masked" iron deficiency when ferritin is 12-100 μg/dL 2
Next Steps Based on Ferritin Results
If ferritin <15 μg/dL (confirmed iron deficiency): 1
- Initiate oral iron supplementation
- Investigate source of iron loss (GI blood loss in men/postmenopausal women, menstrual losses in premenopausal women, dietary insufficiency, malabsorption)
- Consider upper endoscopy and colonoscopy if no obvious source identified 1
If ferritin 15-100 μg/dL with TSAT <30%: 1, 2
- Consider trial of iron supplementation for 3 weeks
- Good response confirms functional iron deficiency
- Poor response warrants bone marrow examination
- Iron deficiency is unlikely
- Evaluate for anemia of chronic disease, thalassemia trait, or other causes
- Consider peripheral blood smear and hemoglobin electrophoresis