Urea-to-creatinine ratio

urea-to-creatinine ratio
LOINC44734-2, 3097-3

In medicine, the urea-to-creatinine ratio (UCR[1]), known in the United States as BUN-to-creatinine ratio, is the ratio of the blood levels of urea (BUN) (mmol/L) and creatinine (Cr) (μmol/L). BUN only reflects the nitrogen content of urea (MW 28) and urea measurement reflects the whole of the molecule (MW 60), urea is just over twice BUN (60/28 = 2.14). In the United States, both quantities are given in mg/dL The ratio may be used to determine the cause of acute kidney injury or dehydration.

The principle behind this ratio is the fact that both urea (BUN) and creatinine are freely filtered by the glomerulus; however, urea reabsorbed by the renal tubules can be regulated (increased or decreased) whereas creatinine reabsorption remains the same (minimal reabsorption).

  1. ^ Albanna, W.; Weiss, M.; Veldeman, M.; Conzen, C.; Schmidt, T.; Blume, C.; Zayat, R.; Clusmann, H.; Stoppe, C.; Schubert, G. A. (2021). "Urea-Creatinine Ratio (UCR) After Aneurysmal Subarachnoid Hemorrhage: Association of Protein Catabolism with Complication Rate and Outcome". World Neurosurgery. 151: e961–e971. doi:10.1016/j.wneu.2021.05.025. PMID 34020058. S2CID 235092726.