Interpreting common paediatric laboratory reference ranges

These three thresholds answer different questions and must not be collapsed into one red flag. [1] [8] [20]

Quote the source of the interval before you argue with a parent or an examiner. Local laboratory ranges on the report are the operational default after verification; large projects such as CALIPER and continuous multi-analyte work explain why those ranges move with age. [1] [9] [25]

Overview & Definition

You open a result and see a red flag. The first job is not to order five more tests. The first job is to ask: what question was this test answering, for which child, on which assay, and is this number even usable? [8]

A laboratory reference interval describes the distribution of results expected in a defined population under stated conditions. In children that population must respect developmental biology. Neonates are not toddlers; pubertal adolescents are not prepubertal schoolchildren. Establishing those intervals is hard because healthy children are difficult to sample at scale, ethics and phlebotomy limits bite hard, and many analytes change continuously with age rather than in neat bins. [8] [27] [28]

CALIPER (Canadian Laboratory Initiative on Pediatric Reference Intervals) was built to close that gap with healthy community children and multiethnic sampling for many biochemical markers. Continuous and big-data approaches later filled finer age resolution for haematology and chemistry where classical partitioning was too coarse. [1] [9] [11] [25]

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