Bladder Function Impairment in Aquaporin-2 Defective Nephrogenic Diabetes Insipidus
| Title: | Bladder Function Impairment in Aquaporin-2 Defective Nephrogenic Diabetes Insipidus |
|---|---|
| Authors: | Shalev, Hanna; Romanovsky, Igor; Knoers, Nine; Lupa, Salomon; Landau, MD, Daniel |
| Publisher: | Nephrology Dialysis Transplantation |
| Date Published: | March 01, 2004 |
| Reference Number: | 644 |
BACKGROUND: The aim of this study was to describe the urological complications associated with nephrogenic diabetes insipidus (NDI) due to a mutation in aquaporin-2 (AQP2), a collecting-duct protein activated by ADH signalling (sic). METHODS: We provide a case series description of a group of seven patients with autosomal recessive NDI due to AQP2 gene mutation, receiving routine medical management since diagnosis in the first months of life. RESULTS: Mean urine osmolarity at diagnosis and last follow-up was 89+/-25 and 83+/-18 mosm/l, respectively. Hydroureteronephrosis was observed in all children, beginning at age 3 years. Two children have daytime enuresis at ages 7 and 10 years and all children older than 6 years continue to have nocturnal enuresis. Markedly enlarged bladders were observed as early as age 4 years in all patients. Trabeculated bladder walls were found in three children. Urodynamic studies performed in two daytime incontinent children revealed a hypotonic-large-capacity type of neurogenic bladder. No impairment in kidney function is currently observed. CONCLUSIONS: The severe renal concentrating defect in this type of NDI is associated with the development of hydroureteronephrosis followed by bladder enlargement and dysfunction. Careful follow-up is needed in order to assure that no bladder outlet obstruction and/or renal insufficiency develop.
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This translation by the NDI Foundation is to assist the lay reader. To provide a clear, accessible interpretation of the original article, we eliminated or simplified some technical detail and complicated scientific language. We concentrated our translation on those aspects of the article dealing directly with NDI. The NDI Foundation thanks the researchers for their work toward understanding and more effectively treating this disorder.
© Copyright NDI Foundation 2007 (JC)
Shalev, et al., report their findings of the medical situation of 9 children in an extended Bedouin family who had NDI resulting from a mutation of the AQP2 gene that resulted in a mutant AQP2 protein. Since two of these children died, the researchers worked with the surviving children and their records.
Despite the fact that these children had been diagnosed with NDI in their infancy and had been following the standard NDI treatment regime (salt restriction, administration of thiazide and prostaglandin inhibitors), each of the children developed massive dilation of their urinary tract that extended beyond the bladder to the ureters (the fibromuscular tube extending from each kidney to the bladder) to portions of the kidney itself. Further, these children developed this distention early in life. This level of urinary tract obstruction can lead to further deterioration of kidney function, and the researchers suggest that these children be monitored closely over the course of their life.
The researchers note that this particular AQP2 mutation produces an AQP2 protein that is unable to function at all, unlike other AQP2 and V2R mutations that result in proteins with some functional ability.