engleski

ePS4.09 Spot urine sodium/creatinine ratio in cystic fibrosis patients and its relation to nutritional status

Objectives: Infants and toddlers with CF are likely to develop sodium depletion, but data on sodium homeostasis in older age groups is scarce. Sodium creatinine ratio in spot urine (UNa/Cr) correlates well with fractional excretion of Na and can serve as a simple marker of normonatremic sodium depletion (NNaD). We investigated the UNa/Cr in children and adults in our CF centre to determine the frequency of Na depletion and its possible association with nutritional status. Methods: We collected basic demographic, anthropometric and laboratory data: plasma Na, spot urine Na and Cr from 55 paediatric and adult patients treated in 2019 in our CF centre. We defined optimal nutritional status as BMI ≥22 kg/m2 for women, ≥23 kg/m2 for men and ≥0 BMI-z-score in children. UNa/Cr ratio was considered pathological if <17 mmol/mmol. Descriptive statistics and Chi square test were performed using statistical package “R”. Results: 30 children (19F, 11M aged 1.3–17.4 yrs, median 9.2 yrs) and 25 adults (14F, 12M aged 18.4–35.1 yrs, median 22.8 yrs) entered the study. Suboptimal nutritional status was noted in 22/30 (73%) of children and 17/ 25 (68%) of adults. All subjects had plasma Na within the normal range and 2 had UNa <20 mmol/L, suggesting an attempt to conserve Na. However, low UNa/Cr was found in a substantially high proportion of both children and adults (15/25 and 14/30, resp. ; p = 0.32). There was no significant difference in the proportion of low UNa/Cr ratio in subgroups divided according to nutritional status, neither in paediatric (p = 0.29) nor adult cohort (p = 0.60). Conclusion: Almost half of subjects of all ages have low UNa/Cr, supporting the hypothesis that CF patients beyond toddlers’ age also suffer from sodium deprivation. The clinical significance of this finding is unclear. Sodium deprivation was described to contribute to poor weight gain, however, in this set of patients, no association of NNaD defined by UNa/Cr and suboptimal nutritional status was established.

cystic fibrosis, Spot urine sodium/creatinine ratio

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