What does a high Mean Corpuscular Hemoglobin Concentration (MCHC) indicate and how is it treated?

High MCHC: Causes, Significance, and Management

A high Mean Corpuscular Hemoglobin Concentration (MCHC) is typically an artifact requiring laboratory investigation rather than a true pathological condition, though in some cases it may indicate underlying hematological disorders that require specific treatment.

Causes of High MCHC

Laboratory Artifacts (Most Common)

• RBC agglutination due to cold agglutinins can cause falsely elevated MCHC readings 1
• Optical interference from lipemia, hemolysis, or other substances in the blood sample 2
• Technical issues with blood cell analyzers that affect measurement accuracy 3

True Pathological Causes

• Hereditary spherocytosis and other RBC membrane disorders 1
• Sickle cell disease, particularly SC disease which can present with abnormally high intracellular hemoglobin concentration 4
• Severe dehydration causing cellular dehydration 3
• Hemoglobinopathies that alter hemoglobin structure and concentration 1

Diagnostic Approach

Initial Assessment

• Review complete blood count (CBC) results, particularly examining MCV, MCH, and RDW alongside MCHC 5
• Check for other abnormal parameters that might indicate a true hematological disorder 6
• Examine peripheral blood smear for morphological abnormalities like spherocytes, sickle cells, or agglutination 1

Laboratory Confirmation

• Request repeat testing after warming the sample to 37°C if cold agglutination is suspected 2
• Consider plasma exchange technique for samples with lipid interference 2
• Use advanced flow cytometric methods that can independently measure volume and hemoglobin concentration for accurate MCHC determination 3

Clinical Significance and Management

For Artifactual High MCHC

• No specific treatment required as this represents a laboratory issue rather than a patient condition 1
• Ensure proper sample collection and handling techniques to minimize interference 2
• Document the artifact to prevent unnecessary diagnostic workup 1

For True Pathological High MCHC

• In hereditary spherocytosis: consider splenectomy for severe cases with hemolysis 1
• In sickle cell disease: hydration therapy may help reduce MCHC to normal values, potentially improving oxygen affinity and reducing sickling 4
• In dehydration: appropriate fluid replacement therapy 3

Monitoring and Follow-up

• Regular monitoring of complete blood count in patients with confirmed hematological disorders 6
• Assessment of reticulocyte count to evaluate bone marrow response in cases with associated anemia 6
• Evaluation for iron deficiency, vitamin B12, or folate deficiency if mixed anemia is present 5

Special Considerations

Cyanotic Heart Disease

• Patients with cyanotic congenital heart disease may have normal or high hemoglobin but can still have iron deficiency, which may be better detected using MCHC than hemoglobin alone 7
• Iron deficiency in these patients (MCHC <31%) has been associated with increased risk of cerebrovascular accidents 7

Methemoglobinemia

• Consider methemoglobinemia in patients with cyanosis and normal oxygen saturation readings 6
• Diagnostic testing includes measurement of MetHb levels using blood gas measurement by co-oximetry 6
• Treatment with methylene blue (1-2 mg/kg) is indicated for symptomatic patients 6

Inflammatory Conditions

• Inflammatory states can affect iron parameters and mask true iron deficiency 6
• Consider measuring CRP to assess for underlying inflammation when evaluating abnormal blood counts 5

Remember that most cases of high MCHC are laboratory artifacts rather than true pathological conditions, but careful evaluation is necessary to distinguish between the two and identify any underlying disorders requiring treatment.