Uremia and the BUN

Abstract

Many physicians regard blood urea nitrogen (BUN) as a measure of renal function, primarily of the glomerular filtration rate (GFR). However, the BUN level depends not only on the efficiency of renal urea excretion but also on the rate of urea production, which in turn depends on catabolic rates of both dietary and endogenous proteins. Thus, a high dietary protein intake may elevate BUN even in the presence of a normal GFR. Furthermore, urea clearance falls markedly, even though GFR remains normal, at low rates of urinary flow, such as rates during water restriction. It is generally agreed that a . . .