Editing Azotemia (section)

=== Primary renal azotemia ===
Renal azotemia (acute kidney failure) typically leads to [[uremia]]. It is an intrinsic disease of the kidney, generally the result of kidney [[parenchyma]]l damage. Causes include [[kidney failure]], [[glomerulonephritis]], [[acute tubular necrosis]], or other [[kidney disease]].<ref name=goljanpath />

The BUN:Cr in renal azotemia is less than 15.{{Citation needed|date=July 2009}} In cases of kidney disease, glomerular filtration rate decreases, so nothing gets filtered as well as it normally would. However, in addition to not being normally filtered, what urea does get filtered is not reabsorbed by the proximal tubule as it normally would be. This results in lower levels of urea in the blood and higher levels of urea in the urine as compared to creatinine. Creatinine filtration decreases, leading to a higher amount of creatinine in the blood. Third-spacing of fluids, as in [[peritonitis]], osmotic diuresis, or [[Hypoaldosteronism|low aldosterone states]] such as [[Addison's disease]] all elevate urea.<ref name=goljanpath />