This book is for medical, nursing, and physician associate students, primary care physicians, and other health professionals who frequently encounter abnormal values on routine laboratory screening tests―such as: The complete blood count (CBC) Metabolic panel Coagulation studies Kidney and liver function tests Lipid profile Thyroid function tests Urinalysis When an abnormality appears unexpectedly, what does it mean? Routine screening tests are often ordered without a particular diagnosis in question, making it more challenging to interpret isolated abnormalities, which may arise from a wide range of possible causes. This book is organized by type of screening test. Each chapter includes tables listing potential causes of elevated or decreased values, along with the underlying pathophysiologic reasoning. It is our hope that this book serves as a useful reference for the day-to-day interpretation of standard screening tests.