... measurements of plasma and urine osmolality revealed an inappropriately high urine osmolality for a given plasma osmolality. Simultaneous plasma vasopressin levels were within normal limits. Urine dilution after water load was normal. During infusion of hypertonic saline, the osmotic threshold was demonstrated...

... a water load. The osmotic threshold was determined by the isovolemic infusion of hypertonic NaCl, and compared to the osmotic threshold of 6 healthy subjects. Random paired urine and plasma osmolality revealed inappropriately high urine osmolality for the given plasma osmolality. A water load produced...