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Urinary aquaporin-2 excretion in nocturnal enuresis
G Radetti1, C Paganini, F Rigon
1Department of Paediatrics, Regional Hospital of Bolzano, Italy. G.Radetti@ntt.it
Insights
Lower urinary aquaporin-2 (AQP-2) excretion is linked to childhood nocturnal enuresis. This finding may explain why some children respond to desmopressin (DDAVP) treatment for bedwetting.
Area of Science:
- Pediatric Nephrology
- Endocrinology
- Urology
Background:
- Nocturnal enuresis affects many children, impacting quality of life.
- The arginine vasopressin (AVP)-aquaporin-2 (AQP-2) axis is crucial for water balance.
Purpose of the Study:
- To investigate the role of the AVP-AQP-2 axis in the development of primary monosymptomatic nocturnal enuresis.
- To differentiate AVP-AQP-2 levels between enuretic children and healthy controls, and between treatment responders and non-responders.
Main Methods:
- Compared 12 children with nocturnal enuresis to 12 healthy controls.
- Measured serum AVP, plasma and urine osmolality, and nocturnal urinary AQP-2 excretion.
- Assessed AVP pituitary storage using MRI.
Main Results:
- No significant differences in mean AVP serum concentrations or urinary AQP-2 between enuretic children and controls.
- Enuretic children had higher plasma osmolality than controls.
- Children who responded to desmopressin (DDAVP) treatment showed significantly lower urinary AQP-2 levels than non-responders.
Conclusions:
- Decreased urinary AQP-2 excretion is associated with nocturnal enuresis in some children.
- This reduced AQP-2 excretion may contribute to the pathogenesis of enuresis.
- It may also predict response to DDAVP treatment in children with nocturnal enuresis.
Objective:
To evaluate the role of the arginine vasopressin (AVP)-aquaporin-2 (AQP-2) axis in the pathogenesis of nocturnal enuresis.
Study Participants:
Twelve children (seven male and five female), aged 11.6+/-4.3 (6.7-15.6) years, suffering from primary monosymptomatic nocturnal enuresis and 12 healthy children, matched for sex and age. Enuretic children were further subdivided into responders and non-responders to treatment with 1-desamino-8-d-AVP (DDAVP).
Methods:
Serum concentrations of AVP, and plasma and urine osmolality were measured at night (0100, 0400 and 0700 h), together with nocturnal urinary excretion of AQP-2 (2000-0800 h). Magnetic resonance imaging (MRI) of the pituitary gland was carried out to evaluate the amount of AVP stored in the posthypophysis.
Results:
Mean AVP serum concentrations were similar in patients and controls. Urinary AQP-2 was also similar in patients and controls, but responders had a significantly lower level of AQP-2 than non-responders (P<0.005). Plasma osmolality was greater in patients than in controls (P<0.001), whereas urinary osmolality was similar in both groups. No difference in the ratio of the signal intensity of the posterior lobe of the hypophysis to that of the pons (AVP content) was found between patients and controls or between responders and non-responders.
Conclusion:
A decreased urinary excretion of AQP-2 is associated with, and seems to have a role in, nocturnal enuresis, at least in some children, and this could also explain why only some of them respond to DDAVP treatment.