Determination of Dose of Lasix in Adult Hydronephrosis and Patients with Chronic Renal Disease

Introduction: Hydronephrosis is a dilation of renal pelvises, calyces or ureters which if untreated would cause severe parenchymal damage leading to loss of function in the affected kidney. The dose of Furosemide and degree of hydration of patients are still debatable. This prospective study evaluated 91 consecutive patients with various renal functions who were known with hydronephrosis or were accidentally found on CT scan or ultra sound. Patients and methods: Ninety-one patients (65 F, 26 M), age (mean 57.2 yrs, range 18-83) underwent renal scintigraphy. All patients prior basal metabolic panel such as eGFR, BUN and Creatinine were reviewed. Patients received 16 Oz of water and voided prior to intravenous injection of approximately 15 mCi Tc99m-DTPA. Following review of the patients’ renal scans, patients were hydrated with another 16 Oz of water and post void received intravenous injection of Lasix. 58 patients received 40 mg, 15 received 60 mg ,16 had 80 mg and 2 received 120 mg. Among these patients, 35 had normal renal function, 1 with stage 1 CKD, 31 stage 2, 19 stage 3, 2 stage 4 and 2 stage 5 chronic kidney disease. The results of renal scans were divided into definitive and intermediate Lasix studies. The patients were followed either medically or surgically for 6 months. Patients were divided into two groups based on dose of Lasix (40 mg and >40 mg). Pearson Chi-squared test was used to compare indeterminate rates between these two groups.

Results: 58 patients received 40 mg of Lasix. GFR mean (SD) was 99.6 (37.7) ml/min with range 37-224 ml/min. There were 44 definitive and 14 indeterminate results, 14/58(24%). 33 patients received higher doses of Lasix based on degree of hydronephrosis or eGFR determination. GFR mean was 63.3 (31.7) ml/min with range 11-140 ml/ min and Lasix dose ranged 60-120 mg. There were 24 definitive and 9 indeterminate results, 9/33 (27%). Seven patients with indeterminate scan had received inadequate dose of Lasix. There was no significant difference between two groups with determination of various Lasix dose administration (P= 0.74). Conclusion: Distinguishing obstructed versus non obstructed kidney disease for definitive therapy in patients with chronic renal disease is challenging. Careful evaluation of the patient prior to study and Lasix dose determination will end with better result. In our study there was no significant difference between the two groups. Larger sample size and more careful determination of dose escalation of Lasix with closer follow up can result in better differentiation prior to surgical versus medical management. Patients with severe hydronephrosis or caliectasis regardless of renal function need to receive a higher dose of Lasix.