What is the clinical significance of low Mean Corpuscular Hemoglobin Concentration (MCHC) and high Basophil (BASOS) percentage in a Complete Blood Count (CBC) with Differential?

Clinical Significance of Low MCHC and High Basophil Percentage in CBC

The low Mean Corpuscular Hemoglobin Concentration (MCHC) of 31.6 g/dL and elevated basophil percentage of 1.1% in this CBC suggest possible iron deficiency in early stages, and should be further evaluated with iron studies and clinical correlation.

Analysis of CBC Results

Normal Parameters

The CBC shows many normal values:

• WBC (5.55 x10³/μL), RBC (5.37 x10⁶/μL), and hemoglobin (15.0 g/dL) are within reference ranges
• Hematocrit, MCV, MCH, RDW are normal
• Differential counts for neutrophils, lymphocytes, monocytes, and eosinophils are normal
• Platelet count and MPV are normal

Abnormal Findings

1. Low MCHC (31.6 g/dL) - Below reference range of 31.7-35.3 g/dL
2. Elevated basophil percentage (1.1%) - Above reference range of 0.0-1.0%
3. Normal basophil absolute count (0.06 x10³/μL) - Within reference range

Clinical Significance of Low MCHC

Low MCHC indicates decreased hemoglobin concentration within red blood cells and is commonly associated with:

• Iron deficiency in early stages - MCHC can decrease before other red cell indices become abnormal 1, 2
• The American College of Physicians recognizes that MCHC may be reduced in early iron deficiency even when hemoglobin and hematocrit remain normal 1
• Studies show that low MCHC can be a reliable marker for screening iron deficiency, with a sensitivity of 38.8% when used alone 3

Since the patient's hemoglobin (15.0 g/dL) is normal, this likely represents early-stage iron depletion rather than established iron deficiency anemia.

Clinical Significance of Elevated Basophil Percentage

Elevated basophil percentage (basophilia) with normal absolute count can be associated with:

1. Chronic myeloid leukemia (CML) - Basophilia is a diagnostic criterion for CML according to European LeukemiaNet guidelines 4
2. Other myeloproliferative disorders - Basophilia can be seen in various myeloproliferative neoplasms 4
3. Inflammatory conditions - Less commonly, basophilia may be seen in allergic reactions or parasitic infections

The European LeukemiaNet guidelines specifically mention that basophils ≥20% in peripheral blood is a criterion for accelerated phase CML 4. However, this patient's basophil percentage of 1.1% is only marginally elevated.

Diagnostic Approach

For Low MCHC:

1. Iron studies - Serum iron, ferritin, total iron binding capacity (TIBC), and transferrin saturation
2. Consider hemoglobin electrophoresis if iron studies are normal
3. Evaluate for potential causes of iron deficiency (gastrointestinal blood loss, menstrual blood loss, poor dietary intake)

For Elevated Basophil Percentage:

1. Repeat CBC to confirm persistent basophilia
2. Peripheral blood smear review to assess cell morphology
3. Consider bone marrow examination if clinically indicated or if other abnormalities develop

Clinical Correlation

The combination of low MCHC and slightly elevated basophil percentage requires clinical correlation:

• If the patient has symptoms of fatigue, weakness, or pallor, iron deficiency is more likely
• If the patient has constitutional symptoms (weight loss, night sweats), splenomegaly, or other concerning features, further evaluation for myeloproliferative disorders should be considered

Monitoring Recommendations

1. Repeat CBC in 2-3 months to monitor for progression of abnormalities
2. Complete iron studies to evaluate for iron deficiency
3. Clinical follow-up to assess for development of new symptoms

Pitfalls and Caveats

1. Pre-analytical factors can affect MCHC, including lipemia and sample storage conditions 5, 6
2. Collection tube type may affect CBC results, though studies show minimal clinically significant differences between standard and microsample tubes 7
3. Isolated mild basophilia is often a nonspecific finding and may be transient
4. Normal CBC parameters do not completely rule out early hematologic disorders 1

The American Society of Hematology recommends that abnormalities in CBC parameters be interpreted in clinical context, as values can be affected by numerous factors including age, sex, and other patient-specific variables 1.