Overview
Why a Technically Successful Draw Can Still Produce a Dangerous Result
A laboratory value is only useful if the specimen truly represents the patient at the moment it was collected.
A laboratory value is only useful if the specimen truly represents the patient at the moment it was collected. Preanalytic errors occur before analysis: wrong-patient labeling, poor collection technique, additive carryover, hemolysis, dilution from IV fluids, delayed transport, or incorrect temperature and light exposure. These errors can look like disease. A hemolyzed specimen may report a dangerously high potassium level even when the patient’s circulating potassium is normal. Blood drawn from a line infusing dextrose may show pseudo-hyperglycemia; saline contamination can produce pseudo-hyponatremia. The experienced nurse notices when a result does not fit the patient, the medication record, or the collection circumstances. Do not dismiss an unexpected result solely because it may be artifactual. Assess the patient and act on immediate threats. For example, a patient with a reported potassium of 6.8 mEq/L plus weakness, bradycardia, or ECG changes needs urgent evaluation and treatment for hyperkalemia while a repeat specimen is obtained. In a stable patient with a hemolysis flag and no clinical evidence of hyperkalemia, notify the appropriate clinician or laboratory and recollect promptly using a technique that reduces...