DDAVP test for assessment of renal concentrating capacity in infants and children.

The renal concentration capacity was tested by intranasal administration of DDAVP in 97 infants and children. The test was simple and reproducible. The renal concentrating capacity increased during approximately the first year of life. At the ages between 1 and 16 years the mean maximal osmolality of 991 mosm/kg was reached. The urine osmolality obtained in the DDAVP test was significantly lower than during the water deprivation test.