Laboratory Anomalies in the Basic Metabolic Panel: Core Curriculum 2025.

Laboratory testing plays an integral part in medical decision making. However, laboratory results can sometimes vary significantly, leading to anomalous outcomes that are not consistent with the clinical picture. These anomalies can occur even in the best of laboratories simply because the total testing process includes elements that are not totally under the laboratory's control. For example, variations in patient preparation and sample collection procedures, as can happen at physician offices or patients receiving intravenous fluids, are major contributors to these anomalies. Therefore, physicians must remain aware of the causes of these anomalies so they can consider them when interpreting laboratory results and help implement solutions to mitigate them at their respective institutions. This Core Curriculum examines several instances where an understanding of preanalytical, analytical, and postanalytical variation is essential for detecting anomalies and providing proper patient care.