A STANDARDIZED DESMOPRESSIN TEST OF RENAL CONCENTRATING ABILITY

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  • 1 January 1980
    • journal article
    • research article
    • Vol. 14  (3) , 142-147
Abstract
Renal concentration tests were carried out on 45 healthy volunteers and 106 patients with chronic renal disease of moderate degree involving impaired concentrating ability. Each subject served as his own control. The control experiment involved a total of 36 h of dehydration (no fluids per os or food with a high fluid content such as fruit) in which 4 h clearance periods were started from the 12th through the 36th h. The first 12 h involved an overnight period from 20.00 h. One week later the same subjects were given 10.mu.g desmopressin (1-desamino-[8-D-Arg]-vasopressin) at the 13th h and a subsequent 4 h clearance period provided blood and urine samples to compare desmopressin-induced urine concentration with various stages of concentration during oral fluid Withdrawal alone. The drug was given intranasally. Urine osmolality and concentrations of urea, Na, K and calculated U/P Urine/plasma creatinine concentration ratios and creatinine clearances (CCr) were measured. Using Uosm (urine osmolarity) as the criterion, the desmopressin experiment at 12 h gave the same results as 24 h of fluid withdrawal alone. With the U/PCr ratio as the criterion, desmopressin + 12 h gave the same results as 36 h of fluid withdrawal alone. Between 32 and 36 h dehydration, CCr decreased, otherwise it remained unchanged in both healthy and ill subjects, with and without desmopressin. The only side-effect was the discomfort of more than 12 h dehydration. This would appear to simplify a potentially useful diagnostic and prognostic test.