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Afternoon urine osmolality is equivalent to 24 h for hydration assessment in healthy children.
Eur J Clin Nutr ; 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31624367


While daily hydration is best assessed in 24-h urine sample, spot sample is often used by health care professionals and researchers due to its practicality. However, urine output is subject to circadian variation, with urine being more concentrated in the morning. It has been demonstrated that afternoon spot urine samples are most likely to provide equivalent urine concentration to 24-h urine samples in adults. The aim of the present study was to examine whether urine osmolality (UOsm) assessed from a spot urine sample in specific time-windows was equivalent to 24-h UOsm in free-living healthy children. SUBJECTS/


Among 541 healthy children (age 3-13 years, female 45%, 77% non-Hispanic white, BMI17.7 ± 4.0 kg m-2), UOsm at specific time-windows [morning (0600-1159), early afternoon (1200-1559), late afternoon (1600-1959), evening (2000-2359), overnight (2400-0559), and first morning] was compared with UOsm from the corresponding pooled 24-h urine sample using an equivalence test.


Late afternoon (1600-1959) spot urine sample UOsm value was equivalent to the 24-h UOsm value in children (P < 0.05; mean difference 62 mmol kg-1; 95% CI 45-78 mmol kg-1). The overall diagnostic ability of urine osmolality assessed at late afternoon (1600-1959) to diagnose elevated urine osmolality on the 24-h sample was good for both cutoffs of 800 mmol kg-1 [area under the curve (AUC) 87.4%; sensitivity 72.6%; specificity 90.5%; threshold 814 mmol kg-1] and 500 mmol kg-1 (AUC 83.5%; sensitivity 75.0%; specificity 80.0%; threshold 633 mmol kg-1).


These data suggest that in free-living healthy children, 24-h urine concentration may be approximated from a late afternoon spot urine sample. This data will have practical implication for health care professionals and researchers.





Texto completo: Disponível Coleções: Bases de dados internacionais Base de dados: MEDLINE Aspecto clínico: Diagnóstico Idioma: Inglês Assunto da revista: Ciências da Nutrição Ano de publicação: 2019 Tipo de documento: Artigo País de afiliação: Estados Unidos