A specimen has UREA ordered. What are potential interferences causing false results?

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A specimen has UREA ordered. What are potential interferences causing false results?

In a urea test that uses a urease-based enzymatic reaction, the measurement depends on the enzyme converting urea to ammonia, which then produces a detectable signal. Substances in the specimen or its container can alter this reaction. Sodium fluoride, the additive in gray-top tubes, can inhibit urease. If fluoride blocks the enzyme, less ammonia is formed from the same amount of urea, so the assay underestimates urea and yields a falsely low result. Ammonia contamination would push results the other way, giving a falsely high reading, while bilirubin and hemolysis can cause readout or matrix effects but do not directly suppress the urease reaction like fluoride does.

In a urea test that uses a urease-based enzymatic reaction, the measurement depends on the enzyme converting urea to ammonia, which then produces a detectable signal. Substances in the specimen or its container can alter this reaction. Sodium fluoride, the additive in gray-top tubes, can inhibit urease. If fluoride blocks the enzyme, less ammonia is formed from the same amount of urea, so the assay underestimates urea and yields a falsely low result. Ammonia contamination would push results the other way, giving a falsely high reading, while bilirubin and hemolysis can cause readout or matrix effects but do not directly suppress the urease reaction like fluoride does.

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