Chapter 11: Nonprotein Nitrogen and Renal Function Flashcards
BUN
Major nitrogen-containing metabolic product of protein catabolism in humans; formed from exogenous and endogenous protein
Glomerular filtration rate (GFR)
In well-hydrated patients: more BUN is excreted, resulting in a lower serum BUN
In a dehydrated patient: Patient’s serum BUN is increased and urine bun is decreased
BUN is dependent on:
Urea concentration, glomerular filtration rate, and level of hydration
Azotemia
Increased blood urea and other NPN; classified into prerenal, renal, and postrenal
Uremia
An increased urea/BUN
BUN:Creatinine (BUN:CR) Ratio
In renal disease, BUN and CR are elevated proportionally. High BUN and a normal/slightly elevated CR is associated with prerenal azotemia; High ratios with an elevated CR is associated with postrenal obstruction
Nessler’s reaction
The addition of a double iodide compound results in the formation of a yellow to orange-brown compound
Creatinine
Synthesized in the liver from arginine, glycine, and methionine; waste product derived from creatine and creatine phosphate
Creatine is affected by:
Relative muscle mass, creatine turnover, and renal function
Creatinine clinical significance
Measures the glomerular filtration rate (GFR); increased serum creatinine is present when the formation or excretion of urine is impaired
Jaffe reaction
Reaction between creatinine and picric acid in an alkaline medium yielding a red-orange compound
Uric acid
Major product of purine (adenine and guanine) catabolism
Renal clearance
The rate at which the kidneys remove a substance from the plasma or blood
Creatinine clearance formula
Clearance = (U x V) / P
U: urine concentration
P: plasma concentration
V: urine flow in mL/minute
Serum protein
Severe renal disease is characterized by decrease in total protein, especially albumin
