An Examination of Serial Urinalyses in Patients with North American Crotalid Envenomation

Abstract

Study Objective: To examine the incidence of abnormal urinalyses after rattlesnake envenomations and its association with bite severity and antivenom administration. Methods: A retrospective review of data collected in a prospective manner for an experimental crotalid antivenom trial. Subjects were individuals with minimal to moderate North American crotalid envenomations. Incidence and characterization of abnormal urinalysis after crotalid envenomation is presented. Additionally, the relationship of abnormal urinalysis to bite severity is examined. A preliminary test of antivenom protein urinalysis interference was also conducted. Results: Forty-three percent of the urinalyses reported prior to antivenom treatment had abnormalities. Thirty-three of 41 subjects (80%) had an abnormal urinalysis, defined as the presence of cells, blood, glucose, or protein, at some time during the 2- week period following envenomation. All but 3 of these subjects had urinalyses which returned to normal by 2 weeks postenvenomation. Fifteen of 22 subjects (68%) with minimal envenomations had an abnormal urinalysis at some time following envenomation, while 18 of 19 subjects (95%) with moderate envenomations had abnormal urinalyses (p < 0.05). In addition, high concentrations of antivenom added to urine were found to produce a positive urine dipstick test for protein. Conclusion: In our study of patients with minimal to moderate North American crotalid envenomations, there was a high incidence of abnormal urinalyses. The urine abnormalities tended to be more common with increased bite severity and more frequent during the first few hours following envenomation. Antivenom appearance in the urine could be responsible for some of our findings.