Laboratory Values: Critical Results, CBC and Electrolytes

Critical Values and Safe Communication Protocols

Critical laboratory values represent measurements falling significantly outside defined safety limits. Because these profound physiological disturbances can signal an immediate life-threatening condition, they demand prompt clinical assessment and rapid escalation. The nurse serves as the primary defense against clinical deterioration when these results are reported, requiring an organized, reliable approach from the moment the laboratory calls.

When receiving a verbal or telephone report of a critical value, the nurse must write down the complete result immediately and read it back to the caller to verify absolute accuracy. Once confirmed, the nurse must promptly notify the healthcare provider in accordance with institutional policy. Waiting for a routine rounding window or delaying escalation for a 30- to 60-minute period is unsafe, as immediate orders are often required to avert catastrophic patient outcomes. Complete documentation must promptly follow, detailing the specific test result, the exact healthcare provider notified, the date, the time, and any resulting clinical orders.

Clinical assessment must always anchor the interpretation of any laboratory result. If a reported value is incongruent with the patient's actual clinical presentation, the nurse must assess the patient first before requesting a laboratory redraw. For example, a hemolyzed blood sample can falsely elevate serum potassium levels. When faced with suspected hemolysis, the nurse assesses the patient and reviews the electrocardiogram, notifies the healthcare provider, and obtains a repeat blood specimen as indicated. However, if hyperkalemia is clinically suspected, urgent treatment must never be delayed while waiting for specimen clarification.