Urine protein as a rapid screen for renal function in the ED: can it replace serum creatinine in selected patients?

Many radiology departments are unwilling to perform studies that require contrast administration to adult emergency department patients over the age of 35 without having a documented serum creatinine concentration of less than 2.0 mg/dl within a week of the study. Significant diagnostic delays may ensue waiting for this serum test. The present study was performed to determine whether a negative urine protein test, obtained by dip testing, will serve as a marker for a serum creatinine concentration below 2.0 mg/dl in emergency department patients who give no history of a disease which potentially could cause renal insufficiency. Emergency patients aged 35 years or more presenting to a university hospital who did not volunteer a history of hypertension, diabetes mellitus, multiple myeloma, or systemic lupus erythematosus in triage were enrolled. Only patients with a negative urine protein test whose serum creatinine was tested for other reasons were included. Of the 310 patients who had no protein in their urine and no history of disease which potentially could cause renal insufficiency, none had a serum creatinine concentration greater than 2.0 mg/dl (mean=0.82 mg/dl, SD 0.28). Ages ranged from 35 to 96 years (mean=59.7 years, SD=17.5). All patients would have qualified for a contrast load for contrast computed tomography studies or for intravenous pyelogram. In patients who do not have a known history of hypertension, multiple myeloma, systemic lupus erythematosus, diabetes mellitus, or specific renal disease, urine dip testing for protein in the emergency department may be a rapid and safe screen for imaging studies requiring contrast without having to await serum creatinine testing.