blood chemistry measurement blood urea level This is the level of urea in the blood; converted from urea nitrogen to urea concentration by multiplying urea nitrogen concentration by 60/28 or 2.14. Urea is the chief nitrogenous end product of protein metabolism in whole blood. Urea is formed in the liver from amino acids and from ammonia compounds and can be found in urine, blood, and lymph. 2022-02-25T09:23:49Z CMO:0003876 blood urea concentration clinical_measurement_ontology slaulede