EM1 Serum creatinine as an indicator for renal CT in acute nephorolithiasis. (Emergency Medicine).

EM1 SERUM CREATININE AS AN INDICATOR FOR RENAL CT IN ACUTE NEPHOROLITHIASIS. John F. Marcucci, MD, Robert Hamilton, MD, and Trevor Mills, MD. Department of Emergency Medicine, University of Texas Southwestern Medical Center, Dallas.

The purpose of this study was to evaluate the need for renal protocol abdomen/pelvis CT in the setting of suspicion of renal stones in the patient with normal creatinine (Cr [less than or equal to]1.2). A retrospective chart review of patients who received a renal protocol CT between Dec 4, 1999 and June 4, 2000 at an urban teaching hospital ED were studied. Charts were analyzed for the following variables: patient demographics, urinalysis, creatinine, and presence of renal stones. 162 charts were reviewed. 44.4% of all charts were positive for renal stones. 129 charts were found to have a documented creatinine drawn on the date of the scan. 110 patients had a Cr [less than or equal to]1.2. Of those patients, 53 were positive for stones and three were admitted. 19 patients had a Cr >1.2. 14 of these were positive for stones and three were admitted. A logistic regression analysis was done to determine if creatinine level predicted having stones and if it predicted outcome of admission or discharge. The creatin ine was not statistically significant of predicting a stone with a P = .71. Additionally, Cr was almost statistically significant of predicting admission to the hospital with a P = .07. Then creatinine was dichotimized with value [less than or equal to]1.2 for the lower level and >1.2 for the upper level. A logistic regression analysis was also performed to determine prediction of stones and admission to hospital. The dichotimized Cr value was statistically significant in determining presence of stones with a P = .047. However, admission to hospital was not statistically significant with a P .18. Creatinine value of [less than or equal to]1.2 alone was nor statistically significant of having a stone and when dichotimized to a Cr of >1.2 was significant for predicting a stone in a large patient population. When predicting admission to hospital Cr alone was not predictive nor was the dichotimized Cr. Based on this limited retrospective study, Cr could not be shown on a case by case basis to be predictive of hav ing a stone or admission to the hospital. If Cr of [less than or equal to]1.2 had been used to electively not scan patients, three of 53 or 5.7% would have been discharged home from the ED who required hospitalization.