Effect of diclofenac on renal function and prostacyclin generation after surgery

We have examined the effect of diclofenac on renal function after major surgery in a randomized, double-blind, controlled study of 20 patients undergoing oesophagogastrectomy. Diclofenac 75 mg or placebo was given i.m. 12-hourly for 2 days. I.v. fluid administration was standardized. Renal function was assessed by fluid balance and measurement of serum creatinine and electrolyte concentrations, creatinine and free water clearance, and urinary sodium and potassium excretion. Urinary 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) was measured by radioimmunoassay to assess renal prostacyclin production. After surgery, 6-keto-PGF1 alpha production increased, but this did not occur with diclofenac. On the first day after surgery, use of diclofenac was associated with a decreased urine flow rate, decreased urinary sodium and potassium excretion and a tendency to hyperkalaemia. Frusemide was required more often in the diclofenac group. One patient was withdrawn from the diclofenac group because of impaired renal function. Urine flow rate and blood potassium concentration should be monitored if diclofenac is used after major surgery.