Critical Thinking Exercise- Spurious Results
Erroneous hemoglobin values are detected by checking Hemoglobin (Hgb) and Hematocrit (HCT)
agreement (rule of three) and the MCHC value. The following are conditions that cause turbidity or
cloudiness that may falsely elevate the hemoglobin measurement performed utilizing photometric
devices:
1.
2.
3.
4.
5.
6.
Hyperbilirubinemia
Hyperlipemia
WBC over linearity
Unlysed RBCs
Hyperproteinemia
Cold Agglutinin
INITIAL RESULTS-36- year old male
Analyte
WBC
RBC
HGB
HCT
MCV
MCH
MCHC
RDW
PLT
Bilirubin, total
Total Protein
Triglyceride
Result
8.4 x 10 / uL
2.45 x106/ uL
9.2 g/dL
21.4 %
87.0 fL
37.5 pg
43.1 %
13.0 %
200 x 103/ uL
0.8 mg/dL
6.7 g/dL
126 mg/dL
3
Reference Range
4.5-11.0 x 103/ uL
4.5-5.5 x106/ uL
14.0-17.4 g/dL
42-52 %
80-100 fL
28-34 pg
32-36 %
12.0-14.6 %
150-450 x 103/ uL
0.2-1.0 mg/dL
6.4-8.3 g/dL
<150 mg/dL
Questions
1.
2.
3.
4.
Do the Hgb and HCT correlate?
Are the MCH and MCHC correct?
If the MCH and MCHC are inaccurate, why?
What can we do to identify the reason for the spurious results?
After the specimen was found to have a cold agglutinin, the sample was warmed and the following
results were obtained.
CORRECTED RESULTS
Analyte
WBC
RBC
HGB
HCT
MCV
MCH
MCHC
RDW
PLT
Result
8.4 x 103/ uL
2.45 x106/ uL
7.4 g/dL
21.1 %
87.0 fL
30.1 pg
35.1 %
13.0 %
210 x 103/ uL
Questions
1. Does the rule of three now correlate?
2. What causes cold agglutinins?