Table 1.

Differences between reference intervals and decision limits

	Reference intervals	Decision limits
Brief definition	The interval between, and including, two reference limits, which are values derived from the distribution of the results obtained from a sample of the reference population.	The best dividing lines between the diseased and the not diseased or between “those who need not be investigated further” and “those who do”.
Conditions influencing them	Type of population Age group Gender	Clinical question Patient category
Information gathered	Whether or not the patient is part of the reference population	Whether or not the patient is eligible for a certain procedure ("treatment")
Statistics	95% central range of the distribution curve	None (consensus values) ROC curves Predictive values
Data number	Two (lower and upper limits) each one with an associated 90% confidence interval	One, without any confidence interval There can be several, but according to the likelihood of various clinical situations or different clinical questions