Background: Laparoscopic cholecystectomy (LC) reduces surgical trauma and hospital stay, but requires effective and safe postoperative analgesia. This prospective and double-blind study investigated the effects of analgesia with tramadol combined with either dipyrone or ketorolac on the postoperative renal function of patients submitted to LC. Methods: Pre-and post-operatively (PO), estimated glomerular filtration rates (GFR), obtained by two formulas dependent on blood Cr and one on blood cystatin C values, and tubular enzymuria—alkaline phosphatase (AP), γ-glutamiltransferase (γ-GT)— were determined in well hydrated patients who underwent LC and analgesia with tramadol combined with either dipyrone (Dipyrone, n = 63) or ketorolac (Ketorolac, n = 63). Upon discharge from the post-anesthetic care unit (PACU), pain (through Verbal Numerical Scale—VNS) and need for rescue analgesia with morphine were evaluated. Results: There was hemodilution PO, which made GFR profile analysis more difficult—those dependent on Cr increased and statistically correlated, but those dependent on cystatin C did not change. There was a significant PO increase in AP in the Dipyrone and Ketorolac groups, and in the product of the both enzymes in the Ketorolac group. Upon PACU discharge, the Dipyrone group showed signifi
cantly higher VNS scores than the Ketorolac group. All patients received morphine PO, and the total dose needed for pain control differed between groups, but without statistical significance. Conclusions: The association of tramadol with dipyrone or ketorolac in well hydrated patients submitted to LC had similar analgesic effectiveness in the PACU. Postoperatively, the effect on GFR may have been masked by hemodilution, and enzymuria was discreetly enhanced when ketorolac was used.