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

It has recently been proposed that the true upper normal limit of serum alanine aminotransferase (ALT) is much lower than that listed by the manufacturers of commercially available assays. The normal ...

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 ...

Urine tests measure specific substances in your urine, such as electrolytes, proteins, and bacteria. These tests can reveal a lot about your health, particularly when gradual changes or big jumps ...