Your doctor says everything looks fine, but you still feel terrible. The problem might not be your health but how labs define “normal.” Understanding the difference between normal and optimal could ...

In this Journal feature, information about a real patient is presented in stages (boldface type) to an expert clinician, who responds to the information by sharing relevant background and reasoning ...

Laboratory reference ranges reflect methods, populations, and policies, and experienced clinicians interpret them in context rather than applying fixed cutoffs theoretically.

DEAR DR. ROACH: I am a 73-year-old female. A recent blood test returned an eGFR (estimated glomerular filtration rate) of 59. My physician’s nurse told me that the test was normal. When I asked her ...

A cystatin C–based blood test may provide a more reliable way to monitor kidney function in children and young adults with SCD, a study found.

Labs calculate normal by testing everyone who walks through the door, including patients with undiagnosed conditions and chronic diseases. The middle 95 percent becomes the reference range, whether ...