“Are my Laboratory Results Normal?” Considerations to be Made Concerning Reference Intervals and Decision Limits

This paper looks at the topic of reference intervals from the point of view of the patient or the clinician. The differences between the concepts of reference intervals (biological characteristic of a well defined population) and the various types of decision limits are illustrated and discussed. Decision limits can be defined in different ways: based on a Bayesian approach, on epidemiological studies or on clinical experience, but differ from reference intervals because, while the latter deals with physiology, decision limits are related to some kind of disease or risk of developing it.