How to manage a patient with low MCHC and high hematocrit?

Management of Low MCHC and High Hematocrit

The primary management approach for a patient with low MCHC (31.3 g/dL) and high hematocrit (46.7%) should focus on phlebotomy to reduce hematocrit while simultaneously addressing the underlying iron deficiency causing the hypochromic red cells.

Understanding the Clinical Picture

• Low MCHC (Mean Corpuscular Hemoglobin Concentration) suggests hypochromic anemia, indicating reduced hemoglobin content within red blood cells 1, 2
• High hematocrit indicates an increased proportion of red blood cells in the blood volume, which can be associated with dehydration or polycythemia 1
• This combination presents a paradoxical situation where the patient has both increased red cell mass (high hematocrit) but decreased hemoglobin concentration within those cells (low MCHC) 3, 2

Diagnostic Workup

Initial Laboratory Testing:

• Complete blood count with peripheral smear to confirm hypochromia and assess for other morphological abnormalities 1
• Iron studies including serum ferritin, transferrin saturation, and total iron binding capacity to assess iron status 1, 2
• Reticulocyte count to evaluate bone marrow response 1
• Hemolysis panel (LDH, haptoglobin, bilirubin) to rule out hemolytic processes 1

Additional Testing Based on Clinical Suspicion:

• Hemoglobin electrophoresis to rule out hemoglobinopathies 1
• Genetic testing for alpha-thalassemia if suspected (especially if iron studies are normal) 1, 2
• Serum erythropoietin level if polycythemia vera is suspected 1
• Assessment of hydration status through BUN/creatinine ratio 1

Management Algorithm

Step 1: Address High Hematocrit

• If hematocrit >46.6% with symptoms of hyperviscosity (headache, blurred vision, dizziness):
  • Perform therapeutic phlebotomy (400-500 ml) to reduce hematocrit to normal range 1
  • Monitor hemoglobin levels during phlebotomy; discontinue if hemoglobin drops below 11 g/dL 1

Step 2: Investigate and Treat Low MCHC

• If iron deficiency confirmed (low ferritin, low transferrin saturation):
  • Initiate oral iron supplementation after phlebotomy has reduced hematocrit 1
  • Avoid iron supplementation before addressing high hematocrit as it may worsen polycythemia 1
  • Consider investigation for sources of blood loss (GI workup, menstrual history) 1

Step 3: Monitor Response to Treatment

• Check hemoglobin, hematocrit, and MCHC weekly until stabilized, then monthly 1
• Target ferritin 50-100 μg/L and transferrin saturation <60% 1
• Adjust frequency of phlebotomy based on hematocrit levels during maintenance phase 1

Special Considerations

• If patient has both polycythemia vera and iron deficiency, phlebotomy remains the treatment of choice but must be balanced to avoid worsening anemia 1
• In cases where phlebotomy is not feasible or poorly tolerated, consider erythrocytapheresis which allows for more selective removal of red cells while returning valuable blood components 1
• Avoid vitamin C supplementation as it can enhance iron absorption and potentially worsen polycythemia 1
• Limit red meat consumption to reduce dietary iron intake 1

Potential Pitfalls

• Do not assume low MCHC is always due to iron deficiency; consider other causes such as alpha-thalassemia which may coexist with polycythemia 1, 2
• Be aware that electronic cell counters may inaccurately measure MCHC in dehydrated cells, potentially underestimating MCHC in patients with high hematocrit 4, 5
• Avoid aggressive phlebotomy in patients with cyanotic heart disease as it may precipitate cerebrovascular accidents despite high hematocrit 3
• Do not initiate iron therapy without first addressing high hematocrit, as this could worsen polycythemia 1

By following this approach, you can effectively manage the seemingly contradictory findings of low MCHC and high hematocrit, addressing both conditions while minimizing risks to the patient.