A plea for intra-laboratory reference limits. Part 2. A bimodal retrospective concept for determining reference limits from intra-laboratory databases demonstrated by catalytic activity concentrations of enzymes

BACKGROUND: The current recommendations for establishing intra-laboratory reference limits (RLs) cannot be fulfilled by most laboratories because of the expense involved. In the current study, a bimodal method was developed to derive RLs from data stored in a laboratory information system without any assumption concerning the distribution of the diseased subgroup. METHODS: A smoothed kernel density function (D(mix)) was estimated for the …