Low-calcium diet in hypercalciuric enuretic children restores AQP2 excretion and improves clinical symptoms.
In this study, we analyzed the effect of a therapeutic intervention in 46 enuretic children, 26 (57%) of whom were hypercalciuric. All the patients (n = 46) were treated with DDAVP for 3-6 mo. The hypercalciuric patients (n = 26) received a low-calcium diet (approximately 500 mg/day) for the same period. After the therapy, the bed-wetting episodes stopped in 80% of the 46 patients tested. In those patients having low-AVP levels before the therapy, circulating AVP concentration returned to normal (>4 pg/ml), and the hypercalciuria was resolved in the hypercalciuric patients (calcium/creatinine ratio <0.2). Urinary aquaporin-2 (AQP2) levels were semiquantified by densitometric scanning and reported as a ratio between the intensity of the signal in the day vs. the night urine samples (day/night AQP2 ratio). In the hypercalciuric patients, the day/night AQP2 ratio returned to values close to those found in the healthy children (from 1.19 +/- 0.20 before to 0.69 +/- 0.10 after the treatment, n = 26, P = 0.03). In contrast, in the normocalciuric children we saw no significant modulation of AQP2 excretion (from 1.07 +/- 0.14 before to 0.99 +/- 0.14 after the treatment, n = 20). This study clearly demonstrates that urinary calcium levels modulate AQP2 excretion and is likely to be useful for treatment of children with enuresis.
Valenti
Giovanna
G
Department of General and Environmental Physiology, University of Bari, 70100 Bari, Italy. g.valenti@biologia.univa.it
Laera
Antonia
A
Gouraud
Sabine
S
Pace
Giuseppe
G
Aceto
Gabriella
G
Penza
Rosa
R
Selvaggi
Francesco P
FP
Svelto
Maria
M
D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins / Q000378:metabolism*; D002136:Calcium, Dietary / Q000008:administration & dosage* / Q000652:urine*; D002648:Child; D003404:Creatinine / Q000652:urine; D004032:Diet; D004231:Diuresis; D004775:Enuresis / Q000178:diet therapy* / Q000652:urine*; D006801:Humans; D044169:Receptors, Calcium-Sensing; D011956:Receptors, Cell Surface / Q000378:metabolism; D016896:Treatment Outcome; D014667:Vasopressins / Q000378:metabolism
C496023:AQP2 protein, human; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins; D002136:Calcium, Dietary; D044169:Receptors, Calcium-Sensing; D011956:Receptors, Cell Surface; D014667:Vasopressins; D003404:Creatinine