Dispersing the Myth of Absolute Certainty: How to Interpret the Results of Endocrine Tests

As clinicians, we are trained to look at a test result and then refer to a reference interval to determine "normal" vs. "abnormal".  However, this determination is often fraught with uncertainty because 1. The result itself is uncertain (because of biological variability and assay imprecision) 2. The cutoffs used to make this decision depend on the sensitivity and specificity of the test as well as the disease prevalence in the tested population.
In this lecture, we will discuss these challenges and give tools to deal with them in the clinic. Analytic imprecision and biological variability will be discussed by a clinical pathologist. Positive and negative predictive values will be discussed by an internist. These concepts will be simplified, clarified, and integrated, and tools will be given to assess and incorporate them into routine clinical work in a practical way.