| Abstrakt: |
1. The effects of intravenous chlorthiazid and frusemide on urinary osmolality were compared in 19 hyponatraemic oedematous patients. 2. Frusemide (1 mg/kg) caused production of a dilute urine (urine/plasma osmolality ratio, Uosm./Posm., 1.64-0.84, P less than 0.01) whereas chlorthiazid (10 mg/Kg) did not (Uosm./Posm, 1.54-1.34, not significant. 3. The Osmolar clearance (Cosm.) was higher after frusemide than after chlorthiazid (11.45 vs 4.99 ml/min, P less than 0.01). When the doses of frusemide (0.25-0.5 mg/Kg) and chlorthiazid (20 mg/Kg) were chosen to give a similar Cosm. (7.25 vs 7.48 ml/min, not significant), the Uosm./Posm. was still lower after frusemide (2.20-1.00, P less than 0.001) than after chlorthiazid (1.75-1.26, P less than 0.01). 4. Exogenous vasopressin did not increase the low Uosm./Posm. after frusemide (1.00-1.00, not significant) but increased the ratio after chlorthiazid (1.34-1.68, p less than 0.01). 5. These results indicate that frusemide, but not chlorthiazid, lead to the excretion of a dilute urine in hyponatraemic oedematous patients. This dilution is not due to a greater solution excretion but is associated with a resistance to the action of vasopressin. |
