Biomarkers in Urine for Children With Monosymptomatic Nocturnal Enuresis and Nocturnal Polyuria

Involuntary voiding during sleep, nocturnal enuresis (NE), affects 7-10 % of all 7-year-olds, and 0.5-2 % of young adults. Night-time polyuria is one of the main pathogenic mechanisms. Today, the only method to diagnose nocturnal polyuria is home recordings involving diaper weight and registrations of first morning voids, which is very time-consuming. By using mass spectrometry (proteomics and metabolomics) on nocturnal urine samples from children with NE, the investigators aim to identify protein markers in relation to nocturnal polyuria. The perspective is to simplify an important part of the clinical characterization of NE patients.

This hypothesis-generating pilot project will be performed on 10 boys with NE. The children will have to collect:

• Urine at bedtime on a wet and a dry night.
• Urine during a wet night through a collecting device (non-invasive).
• First morning voided volume following both a wet and a dry night.

Furthermore, we will include 10 children without NE, who will collect urine during a dry night (first morning voided volume).

Endpoints are any biomarkers in urine found to be associated with nocturnal polyuria.

The proteomics and metabolomics methodologies are available at the proteomics core facility of Research Unit for Molecular Medicine, Dept. of Clinical Medicine, Aarhus University Hospital.

Based on the analytical uncertainty of the protein analysis methods, 10 samples are sufficient for detecting down to two-fold alterations in protein levels (p<0.05). By using state of the art mass spectrometry, the difference in any protein level between 1) the total urine amount on a wet and a dry night, and 2) first morning voided volume on a wet and a dry night, will be evaluated. Furthermore, difference in urine composition between children with NE and healthy children will be evaluated. Student's t-test with significance level at p<0.05 will be used.The amount of proteins in each urine sample will be correlated to the total amount of proteins in the respective sample.

Inclusion criteria

• Monosymptomatic nocturnal enuresis with at least one dry night per week.
• Nocturnal polyuria defined as nocturnal urine production on wet nights greater than 130 % of expected bladder capacity for age.
• Normal bladder capacity defined as maximum voided volume excluding first morning voided volume bigger than expected bladder capacity for age.

Exclusion criteria

• Recurrent urinary tract infections.
• Anamnestic, clinical or laboratory findings that can be related to diseases or conditions that might affect the parameters investigated.
• Neurological and/or known clinically significant anatomical abnormalities of the urinary tract.
• Former operations in the urinary tract.
• Ongoing medication that may interfere with the parameters tested.

If the child is receiving treatment for nocturnal enuresis (desmopressin, alarm or anticholinergics), the treatment has to be paused 1 week before urine collection.

Furthermore, we will include 10 children without nocturnal enuresis and otherwise healthy.