engleski

P265 Normonatremic sodium depletion and pulmonary function in cystic fibrosis patients

Objectives: Spot-urine ratio of sodium and creatinine (UNa/Cr) <17 mmol/ L/mmol/L points to normonatremic sodium depletion (NNaD), a condition recognised in CF patients. NNaD could contribute to additional mucus thickening and therefore worsening of lung function. We investigated the UNa/Cr in paediatric and adult patients and looked for possible association with FEV1 measurements. Methods: We collected basic demographic, anthropometric and laboratory data (plasma Na, BUN, spot urine Na and Cr) and FEV1 measurements from 36 paediatric and adult patients seen during 2019 in our CF centre. Patients were divided in subgroups depending on percent predicted FEV1 values: group A (FEV1 < 60%), group B (FEV1 60–80%), and group C (FEV1 >80%). Descriptive statistics, Chi-square and Fisher’s exact test were performed (statistical package “R”). Results: Twenty adults and 16 children were included in the analysis, all normonatremic and with normal kidney function. Two subjects had UNa < 20 mmol/l, indicating kidney Na conservation. Pathological UNa/Cr ratio was found in 13 adults and 7 children, or 20/36 (55%) patients. 26/36 had suboptimal BMI ; 15 of them NNaD as well. Low UNa/Cr ratio across FEV1-subgroups was found in 8/17(47%), 4/6 (66%) and 8/13 (62%) patients in groups A, B and C, resp. There was no significant association between UNa/Cr ratio and FEV1 subgroups (chi:0.942, p = 0.3). Conclusion: The observed high proportion of pathological UNa/Cr in all ages speaks in favour of NNaD as a lasting problem in some CF patients. Although previously described in literature, poorer weight gain was not related with NNaD in our subjects (p = 0.7). We did not find a significant relation of UNa/Cr and FEV1 categories. However, lung function decline is connected to many factors (chronic infection, pulmonary exacerbation rate, nutrition, adherence to therapy etc.), that were not taken in consideration in our analysis. Further studies are justified in order to elucidate the clinical spectre of NNaD.

cystic fibrosis, Normonatremic sodium depletion

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