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Questions and Answers
What is one potential cause of artifactual hyperkalemia when blood is taken from patients with thrombocytosis?
What is one potential cause of artifactual hyperkalemia when blood is taken from patients with thrombocytosis?
What practice can help prevent increased potassium levels due to thrombocytosis during blood collection?
What practice can help prevent increased potassium levels due to thrombocytosis during blood collection?
How does clenching the fist excessively before venipuncture affect potassium levels?
How does clenching the fist excessively before venipuncture affect potassium levels?
What is the recommended temperature to store whole blood samples for K+ determinations?
What is the recommended temperature to store whole blood samples for K+ determinations?
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What can result from hemolysis of blood samples after collection?
What can result from hemolysis of blood samples after collection?
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What approximate increase in potassium is associated with slight hemolysis of about 50 mg/dL of hemoglobin?
What approximate increase in potassium is associated with slight hemolysis of about 50 mg/dL of hemoglobin?
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What is the maximum estimated increase in potassium levels due to gross hemolysis of more than 500 mg/dL of hemoglobin?
What is the maximum estimated increase in potassium levels due to gross hemolysis of more than 500 mg/dL of hemoglobin?
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Which of the following practices should be avoided to prevent artifactual hyperkalemia during sample collection?
Which of the following practices should be avoided to prevent artifactual hyperkalemia during sample collection?
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Study Notes
Sample Collection for Potassium (K+) Analysis
- Proper sample collection crucial for accurate K+ analysis. Artifactual hyperkalemia (falsely high K+) has many causes.
- Coagulation and Platelets: Serum K+ may be 0.1–0.7 mmol/L higher than plasma K+ due to K+ release from platelets. High platelet counts (thrombocytosis) further elevate serum K+.
- Tourniquets and Muscle Contraction: Prolonged tourniquet use, muscle clenching, or exercise before venipuncture release K+ from cells into the plasma.
- Preventing Artifactual Hyperkalemia: Use heparinized tubes to prevent clotting, and handle patients gently before blood draw.
- Storage and Analysis: Storing blood on ice releases K+ from cells, so room temperature storage is preferred. Analyze samples promptly or centrifuge to separate cells before analyzing.
- Hemolysis: Hemolysis (rupturing of red blood cells) after blood draw is the most common cause of artifactual hyperkalemia. Slight hemolysis (≈50 mg/dL hemoglobin) increases K+ by about 3%. Gross hemolysis (>500 mg/dL hemoglobin) raises K+ by up to 30%.
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Description
Explore the critical procedures for proper sample collection in potassium (K+) analysis. Understand the potential impacts of artifacts such as hyperkalemia, methods for preventing them, and best practices for sample handling and storage.
