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Questions and Answers
Which factor can lead to a falsely increased hematocrit result?
Which factor can lead to a falsely increased hematocrit result?
What is the expected hemoglobin value calculated using the Rule of Three for an RBC count of $5.4 \times 10^{12}/L$?
What is the expected hemoglobin value calculated using the Rule of Three for an RBC count of $5.4 \times 10^{12}/L$?
Which situation would likely cause a falsely decreased hematocrit?
Which situation would likely cause a falsely decreased hematocrit?
What discrepancy was identified in Case 2 regarding the Rule of Three?
What discrepancy was identified in Case 2 regarding the Rule of Three?
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What is a possible reason for inaccuracies in hematocrit results in Case 2?
What is a possible reason for inaccuracies in hematocrit results in Case 2?
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Study Notes
Potential Causes of Errors in Hematocrit
- Certain abnormal red blood cell (RBC) shapes (e.g., spherocytes, sickle cells) can prevent complete packing, leading to inaccurate hematocrit (Hct) readings.
- Immediately after blood loss, plasma volume is replenished more quickly than RBCs, resulting in a temporarily lower Hct.
Causes of Falsely Increased Hematocrit
- Dehydration
- Hemoconcentration
- Insufficient centrifugation
- Buffy coat inclusion
Causes of Falsely Decreased Hematocrit
- Hemolysis
- Improper sealing of cap in sample tube
- Introduction of excess fluid (interstitial fluid)
- Increased anticoagulant concentration
Rule of Three for Hematologic Tests
- Used to verify the validity of test results for normocytic, normochromic specimens.
- Formula: RBC x 3 = Hemoglobin (Hgb), and Hgb x 3 = Hct
Sample Cases
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Case 1 (Accurate Specimen): Male patient with RBC count of 5.4 x 1012/L, Hemoglobin (Hgb) of 16.4 g/dL, and Hematocrit (Hct) of 49%. Expected values calculated using the rule of three: 5.4 x 3 = 16.2(Exp. Hgb), and 16.4 x 3 = 49.2 (Exp Hct)
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Case 2 (Inaccurate Specimen): Male patient with RBC count of 4.0 x 1012/L, Hgb of 3.2 g/dL, and Hct of 37%. Calculated using the rule of three : 4.0 x 3 = 12 (Exp. Hgb), and 3.2 x 3 = 9.6 (Exp Hct). Errors may include machine malfunctions or non-normocytic/non-normochromic specimens.
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Description
Explore the various potential causes of errors in hematocrit readings, including both falsely increased and decreased values. Understand the significance of the Rule of Three in verifying test results. This quiz will assess your knowledge on hematologic tests and the factors influencing hematocrit accuracy.
