A CBC on a 45-year-old female shows low RBC, low Hgb, low Hct, high MCV, and high MCHC; what is the most likely cause and how should the specimen be resolved?

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Multiple Choice

A CBC on a 45-year-old female shows low RBC, low Hgb, low Hct, high MCV, and high MCHC; what is the most likely cause and how should the specimen be resolved?

When a CBC shows a pattern that doesn't fit a true patient condition, look for preanalytic issues with the specimen. Hemolysis before analysis causes red cells to rupture, which lowers the intact RBC count, the measured hemoglobin, and the hematocrit. At the same time, the analyzer can compute an apparently higher MCV and MCHC because of the altered relationship between the measured hemoglobin and hematocrit and because free hemoglobin in plasma and damaged cells can interfere with the measurements. This combination—low RBC, low Hgb, low Hct with elevated MCV and elevated MCHC—is a classic sign that the specimen is hemolyzed rather than reflecting the patient’s true physiology. To resolve this, the specimen should be processed with the aim of removing the interference and obtaining a reliable measurement, which in practice means correcting for the hemolysis and re-running after ensuring a clean sample. This often involves clarifying or preserving steps (such as centrifuging to separate components and adjusting or diluting as needed) and, if necessary, collecting a new specimen to ensure accurate results. If the pattern persists after attempting salvage, recollecting a new blood sample is indicated. This approach contrasts with iron-deficiency anemia, which would typically present with a low MCV (microcytosis) and would not usually produce a high MCHC.

When a CBC shows a pattern that doesn't fit a true patient condition, look for preanalytic issues with the specimen. Hemolysis before analysis causes red cells to rupture, which lowers the intact RBC count, the measured hemoglobin, and the hematocrit. At the same time, the analyzer can compute an apparently higher MCV and MCHC because of the altered relationship between the measured hemoglobin and hematocrit and because free hemoglobin in plasma and damaged cells can interfere with the measurements. This combination—low RBC, low Hgb, low Hct with elevated MCV and elevated MCHC—is a classic sign that the specimen is hemolyzed rather than reflecting the patient’s true physiology.

To resolve this, the specimen should be processed with the aim of removing the interference and obtaining a reliable measurement, which in practice means correcting for the hemolysis and re-running after ensuring a clean sample. This often involves clarifying or preserving steps (such as centrifuging to separate components and adjusting or diluting as needed) and, if necessary, collecting a new specimen to ensure accurate results. If the pattern persists after attempting salvage, recollecting a new blood sample is indicated. This approach contrasts with iron-deficiency anemia, which would typically present with a low MCV (microcytosis) and would not usually produce a high MCHC.

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