Copeptin and albumin in children with undernutrition

Anthropometric assessment remains the cornerstone of the identification and classification of pediatric undernutrition, whereas the role of laboratory biomarkers is less well established.

To evaluate serum copeptin in children with undernutrition and to compare its discriminatory performance with that of serum albumin.

This single-center cross-sectional case-control study included children aged 1 month to 18 years with undernutrition and healthy controls recruited from the same clinical setting. Serum copeptin concentrations were measured by enzyme-linked immunosorbent assay. Receiver operating characteristic analysis and multivariable logistic regression were performed. Age-stratified and sensitivity analyses were also conducted.

A total of 98 children were included: 44 with undernutrition and 54 healthy controls. Serum copeptin concentrations were significantly higher and serum albumin concentrations were significantly lower in children with undernutrition than in healthy controls (both p < 0.001). In ROC analysis, copeptin yielded an area under the curve of 0.729 (95% CI 0.622-0.835), whereas albumin yielded an area under the curve of 0.726 (95% CI 0.618-0.833), with no significant difference between the two ROC curves (DeLong p = 0.977). In multivariable analysis adjusted for age and sex, both copeptin and albumin remained independently associated with undernutrition. A combined copeptin-albumin model showed higher discrimination within the study sample.

Serum copeptin is elevated in children with undernutrition. Although it does not outperform albumin as a standalone biomarker, it may provide complementary information when interpreted alongside albumin.