Treatment of Abnormal MCHC
Low MCHC Management
The primary treatment for low MCHC is oral iron supplementation for 3-6 months after hemoglobin normalization, with mandatory investigation for the underlying cause of iron deficiency. 1
Diagnostic Workup
- Obtain complete blood count with RBC indices, serum ferritin, and C-reactive protein as the minimum initial workup 2
- Measure serum iron and transferrin saturation to confirm iron deficiency 1
- Without inflammation: serum ferritin <30 μg/L confirms iron deficiency 1
- With inflammation: serum ferritin up to 100 μg/L may still indicate iron deficiency 1
- Transferrin saturation <20% with ferritin >100 μg/L suggests anemia of chronic disease rather than pure iron deficiency 1
Investigation of Underlying Cause
In adult men and post-menopausal women, perform both upper endoscopy and colonoscopy to exclude gastrointestinal malignancy, as GI blood loss is the most common cause 1
- Obtain small bowel biopsy during endoscopy to rule out celiac disease 1
- In pre-menopausal women, assess menstrual blood loss patterns 1
- Screen for NSAID use causing occult GI bleeding 1
- Evaluate for malabsorption in patients with gastrointestinal symptoms 1
- Consider chronic kidney disease as a contributing factor 1
Treatment Protocol
Start oral iron therapy as first-line treatment for most patients with confirmed iron deficiency 1
- Continue oral iron for 3-6 months after hemoglobin normalization to replenish iron stores 1
- Use intravenous iron in patients with malabsorption, inflammatory bowel disease, or when rapid repletion is needed 1
- Calculate total iron requirement based on hemoglobin level and body weight 1
Monitoring Strategy
- Repeat CBC after 4-8 weeks of treatment to assess response 1
- Monitor serum ferritin to ensure adequate iron store repletion 1
- For persistent or recurrent iron deficiency: reassess medication compliance, perform repeat endoscopic evaluation, and evaluate for occult blood loss sources 1
Special Clinical Scenarios
In cyanotic congenital heart disease patients, low MCHC indicates iron deficiency superimposed on polycythemia, creating a particularly dangerous situation that increases risk of cerebrovascular accidents 2, 3
- Iron deficiency in cyanotic heart disease produces rigid, less deformable microcytic hypochromic red cells in microcirculation 2
- MCHC <31% in cyanotic patients warrants aggressive iron replacement 3
- In chronic kidney disease, follow disease-specific anemia management guidelines 1
Important Caveats
- Low MCHC with normal MCV may represent early iron deficiency before microcytosis develops 1
- Serum ferritin can be falsely elevated in inflammatory states, making diagnosis challenging 1
- Combined deficiency states (iron with concurrent B12 or folate deficiency) can present with low MCHC 1
- Consider hemoglobinopathies (thalassemia, sickle cell disease) in the differential diagnosis 1
High MCHC Management
High MCHC is often a laboratory artifact requiring verification before pursuing extensive workup 4, 5
Initial Approach
- Review complete blood count results, examining MCV, MCH, and RDW alongside MCHC to identify true hematological disorders 4
- Check for cold agglutination interference by warming sample to 37°C 5
- Evaluate for lipemia interference and consider plasma exchange if present 5
True High MCHC Evaluation
- Assess reticulocyte count to evaluate bone marrow response 4
- Consider methemoglobinemia in patients with cyanosis and normal oxygen saturation readings 4
- Measure methemoglobin levels using blood gas co-oximetry 4
- Treat symptomatic methemoglobinemia with methylene blue 1-2 mg/kg 4
- Measure CRP to assess for underlying inflammation affecting iron parameters 4