Bonnet L, Marquant E, Fromonot J, et al. - Researchers aimed at determining the copeptin threshold that may aid in differentiating patients with central diabetes insipidus from those with primary polydipsia. Further, they investigated the normal range of copeptin concentrations in children.

• A single-center retrospective descriptive study of 278 children (aged 2 months to 18 years) who consulted for polyuria-polydipsia syndrome (PPS) (N = 40) or other reasons (control group, N = 238) and had a copeptin assay.

• Findings suggest copeptin assays as valuable in the differential diagnosis of PPS in children.

• Among the children with PPS, those with central diabetes insipidus (N = 21), nephrogenic diabetes insipidus (N = 3), and primary polydipsia (N = 16) had mean copeptin concentrations of 1.72, 55.2 and 15.7 pmol/l, respectively.

• For central diabetes insipidus, diagnostic was copeptin levels lower than 3.53 pmol/l with 100% sensitivity and 87.4% specificity.

• The control group had the 5th–95th copeptin percentile range of 2.53–21.03 pmol/L. Relative to girls, boys had significantly higher copeptin levels.