Urinary aquaporin-2 excretion in nocturnal enuresis

Abstract

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 ®ve female), aged 11X6^4X3 (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 signi®cantly lower level of AQP-2 than non-responders P , 0X005X Plasma osmolality was greater in patients than in controls P , 0X001Y 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.

Urinary aquaporin‐2 as a possible objective biomarker of nocturnal polyuria

“…In this study, we used the first morning void urine samples to measure urinary AQP2/Cr owing to the convenience of this method. The results were consistent with previous studies that used collection urine samples . This suggests that evaluation of urinary AQP2/Cr using first morning void urine might be useful as a screening method for the diagnosis of NP.…”

“…In previous studies, urinary AQP2 expression in NE patients decreased at night . Furthermore, urinary AQP2 expression during night‐time increased on treatment in NE patients who responded to DDAVP, although there was no significant difference in its expression at baseline between patients who responded and those who did not .…”

Excess diuresis and natriuresis during acute sleep deprivation in healthy adults

“…Enuresis in children and nocturia in elderly is in many cases the result of excess nocturnal urine production. Disturbances in the vasopressin-aquaporin (AQP) axis (38,37) have long been considered as the basis of the nocturnal polyuria seen in enuresis. However, during recent years, factors outside of this axis have also been implicated.…”

Molecular biology of water and salt regulation in the kidney

“…Treatment with the vasopressin analogue DDAVP (1-desamino-8-Darginine vasopressin) improves such symptoms in most cases. There have been studies in which a decrease in aquaporin-2 excretion has been detected in the urine of patients with nocturnal enuresis compared to controls [54]. After treatment with DDAVP normalization of excretion of aquaporin-2 was observed in most of these patients coinciding with the disappearance of the nocturnal enuresis [54].…”