Hypercalciuria in children with monosymptomatic nocturnal enuresis

Differences in the urinary metabolome and proteome between wet and dry nights in children with monosymptomatic nocturnal enuresis and nocturnal polyuria

BACKGROUND

Nocturnal enuresis (NE) is a common disease with multiple pathogenic mechanisms. This study aimed to compare levels of metabolites and proteins between wet and dry nights in urine samples from children with monosymptomatic NE (MNE).

METHODS

Ten boys with MNE and nocturnal polyuria (age: 7.6 ± 1.3 years) collected their total nighttime urine production during a wet and a dry night. Untargeted metabolomics and proteomics were performed on the urine samples by liquid chromatography coupled with high-mass accuracy tandem mass spectrometry (LC-MS/MS).

RESULTS

On wet nights, we found reduced urine osmolality (P = 0.025) and increased excretion of urinary potassium and sodium by a factor of, respectively, 2.1 (P = 0.038) and 1.9 (P = 0.19) compared with dry nights. LC-MS identified 59 metabolites and 84 proteins with significantly different levels between wet and dry nights (fold change (FC) < 0.67 or > 1.5, P < 0.05). Some compounds were validated by different methodologies. During wet nights, levels of compounds related to oxidative stress and blood pressure, including adrenalin, were increased. We found reduced levels of aquaporin-2 on wet nights. The FCs in the 59 metabolites were positively correlated to the FCs in the same metabolites identified in urine samples obtained during the evening preceding wet and dry nights.

CONCLUSIONS

Oxidative stress, which in the literature has been associated with nocturia and disturbances in sleep, might be increased during wet nights in children with MNE. We further found evidence of increased sympathetic activity. The mechanisms related to having wet nights in children with MNE seem complex, and both free water and solute handling appear to be important. A higher resolution version of the Graphical abstract is available as Supplementary information.

Calciuria in children with primary mono-symptomatic nocturnal enuresis

Introduction: The prevalence of idiopathic hypercalciuria (IH) in healthy pediatric population ranges from 3.0% to 7.0%. There is insufficient data about IH in children with mono-symptomatic enuresis. The aim of this study was to examine calcium excretion in urine (UCa) in patients with primary mono-symptomatic nocturnal enuresis (PMNE). Methods: In patients with PMNE, aged 5 to 17 years, IH was determined in 24-h urine and from second morning spot urine. The completeness of the 24-h urine collections was estimated via measuring 24h-urine creatinine excretion (UCr) of 0.1-0.2 mmol/kg/24h. Results: Sixty patients with PMNE, 32 males and 28 girls, median age of 9 years were enrolled in the study. Only 41.7% patients successfully completed 24 h urine collection. IH, defined as 24-h UCa > 0.1 mmol/kg body weight, was diagnosed in 12% of the patients, while when defined as UCa/UCr > 0.8 mmol/mmol in children 5-7 years and > 0.6 mmol/mmol in those > 7 years, IH was 8.3% and 6.7% from 24hurine and spot urine, respectively. Conclusion: Children and adolescents with PMNE are in risk of hypercalciuria. Therefore, it is useful to examine 24 hours of urine calcium excretion in these patients.

Urinary calcium excretion in children with monosymptomatic enuresis

Background

Among many factors predisposing to monosymptomatic enuresis (MNE) disturbances in urinary electrolites excretion play an important role. Because of many controversies in this field there is a need to debate the role of hypercalciuria in MNE. The aim of our study was to determine the urinary calcium in children with MNE.

Methods

The investigation was conducted on 204 children (83 MNE children and 121 reference group). Urinary calcium excretion (in 24-h collection and per kg of body mass), Ca/creatinine ratio, Ca²⁺ in urine sample and in 24-h collection of urine were estimated.

Results

Hypercalciuria in MNE group was diagnosed in 18/83 (21.69 %) patients. We found statistically significant differences between children with MNE in Ca²⁺ in urine sample and 24-h collection and Ca/creat. ratio. Median urinary calcium excretion (mg/kg/24-h and mmol/24-h) was significantly higher in hypercalciuric enuretic patients. The urinary total calcium (mmol/24-h), urinary bound calcium and urinary calcium concentration (mmol/L) demonstrated a significant positive correlation with height, weight and age in reference group but not in MNE group.

Conclusion

Urinary calcium excretion was significantly disturbed and further studies are needed to assess the role of hypercalciuria in the pathogenesis of MNE.