It depends on the value and as always, the physician’s clinical judgment and documentation as well as the condition guidelines.

Most of the time, laboratory tests are repeated after a few months to ensure the value was not an aberration or lab error. The rule of thumb is to wait for the second positive lab value to diagnose a condition. However, lab values that show a trend, such as the HbA1C, can be used to diagnose diabetes after the first elevated result.

We never recommend that you question a clinician on a clinical judgment issue like this unless you have specific guidelines from a health plan, for example, that requires a certain number of positive lab values before making a diagnosis.