DDAVP test for renal concentration capacity. Age-related reference intervals.

The effect of different levels of fluid intake on the renal concentration test was evaluated. Maximal urinary osmolality did not significantly differ whether strict fluid restriction was kept or not. One side effect, namely headache, seemed more frequent after fluid deprivation than after a more liberal fluid intake. We suggest a practical approach to the performance of the urinary concentration test with DDAVP. The maximal urinary concentration after a single subcutaneous injection of 4 micrograms DDAVP was determined in 212 healthy adults aged 20 to 80 years. A significant decline with age was found in maximum urinary concentration, mean values ranging from 982 mOsm/kg at 20 years to 823 mOsm/kg at 80 years. References are given for different ages which render the test useful in adult patients.