Based on the CBC result shown, what could possibly be the cause of error? WBC: 9.21x10^9/L RBC: 4.17x10^12/L HGB: 14.9 g/dL HCT: 32.5% MCV: 77.9 fL MCH: 35.7 pg MCHC: 45.8 g/dL

Based on the CBC result shown, what could possibly be the cause of error? WBC: 9.21x10^9/L RBC: 4.17x10^12/L HGB: 14.9 g/dL HCT: 32.5% MCV: 77.9 fL MCH: 35.7 pg MCHC: 45.8 g/dL

• A. Presence of cold agglutinins
• B. Lipemic sample
• C. Old specimen
• D. Result is not erroneous, report

Answer: (B)

The main idea is that an extremely high MCHC value with otherwise normal hemoglobin and a discordant index pattern often points to an instrument interference rather than a true blood abnormality. MCHC is calculated from hemoglobin and hematocrit, and here it comes out as about 45.8 g/dL, which is far above the normal range. Such a spike typically signals an analytical artifact. Lipemic samples (milky/plasma turbidity from high lipid content) are a common cause of this kind of interference because the turbidity scatters light and disrupts the photometric measurements used to determine hemoglobin and hematocrit on many analyzers, yielding a spuriously high MCHC. The presence of microcytosis by MCV could be a real finding or another artifact, but the key point is that the unphysiologic MCHC suggests the sample quality issue—lipemia. If feasible, a repeat sample after lipids are cleared or using an alternate measurement method would help confirm the result. Cold agglutinins or an old specimen could cause other discordances, but they don’t typically produce such a marked and isolated MCHC elevation in this pattern.

The main idea is that an extremely high MCHC value with otherwise normal hemoglobin and a discordant index pattern often points to an instrument interference rather than a true blood abnormality. MCHC is calculated from hemoglobin and hematocrit, and here it comes out as about 45.8 g/dL, which is far above the normal range. Such a spike typically signals an analytical artifact. Lipemic samples (milky/plasma turbidity from high lipid content) are a common cause of this kind of interference because the turbidity scatters light and disrupts the photometric measurements used to determine hemoglobin and hematocrit on many analyzers, yielding a spuriously high MCHC. The presence of microcytosis by MCV could be a real finding or another artifact, but the key point is that the unphysiologic MCHC suggests the sample quality issue—lipemia. If feasible, a repeat sample after lipids are cleared or using an alternate measurement method would help confirm the result. Cold agglutinins or an old specimen could cause other discordances, but they don’t typically produce such a marked and isolated MCHC elevation in this pattern.