Differential diagnosis

Endocrinology

Polyuria

Vasopressin

Diabetes insipidus

Pediatrics

Polydipsia

Internal medicine

Medicine

Copeptin

Pathology

Diabetes mellitus

Clinical Endocrinology

Polyuria-polydipsia syndrome (PPS) is a common presentation in children but the differential diagnosis rests on burdensome water deprivation tests. The aims of this study were to determine a copeptin threshold to distinguish patients with central diabetes insipidus from those with primary polydipsia and to estimate the normal range of copeptin concentrations in children.Single-centre retrospective descriptive study.Two hundred and seventy-eight children aged 2 months to 18 years who consulted for PPS (N = 40) or other reasons (control group, N = 238) at La Timone University Hospital in Marseille, France, between April 2015 and September 2019 and had a copeptin assay.Ultrasensitive copeptin assays on blood samples.Among the children with PPS, the mean copeptin concentrations were 1.72, 55.2 and 15.7 pmol/l in those with central diabetes insipidus (N = 21), nephrogenic diabetes insipidus (N = 3), and primary polydipsia (N = 16), respectively. Copeptin levels lower than 3.53 pmol/l were diagnostic of central diabetes insipidus with 100% sensitivity and 87.4% specificity (p < .001). The 5th-95th copeptin percentile range in the control group was 2.53-21.03 pmol/L. Copeptin levels were significantly higher in boys than in girls but there was no association with age, pubertal stage, body mass index, or the reason for consulting.Our results indicate copeptin assays may be valuable in the differential diagnosis of PPS in children. Larger prospective studies are required to establish their accuracy in everyday clinical practice.

Copeptin assays in children for the differential diagnosis of polyuria‐polydipsia syndrome and reference levels in hospitalized children