NPN Compounds Flashcards
Explain the chemical structure, synthesis and mode of excretion or urea
State the principle of the chemical reaction, sample types required, reference interval, most common interfering substances/ source of error, and the usefulness of the BUN assay
-Major excretory product of protein metabolism/catabolism
-These processes release nitrogen, which is converted to ammonia
-Synthesized in the liver from CO2 and Ammonia that arises from deamination of amino acids
-Ref range serum: 6-20 mg/dL
-24-hour urine ref range: 12-20 g/dL
-Assays for urea were based on measurement of nitrogen, the term blood urea nitrogen (BUN) has been used to refer to urea determination.
-Excreted by the kidneys - 40% reabsorbed
-<10% of the total are excreted through the gastrointestinal tract and skin.
-Concentration is determined by: renal function, dietary intake, protein catabolism
Measurement of urea is used to:
-evaluate renal function
-Assess hydration status (the amount of urea reabsorbed depends on urine flow rate and extent of hydration.
-Determine nitrogen balance
-Aid in the diagnosis of renal disease
-And to verify adequacy of dialysis
Azotemia
elevated concentration of urea in blood
uremia or uremic syndrom
very high plasma urea concentration accompanied by renal failure
Discuss ideas states and disorders associated with urea measurements in pre-renal causes
-reduced renal blood flow –> Less blood is delivered to the kidney –> less urea filtered
-Anything that produces a decrease in functional blood volume, include: Congestive heart failure, shock, hemorrhage, dehydration, burns
-High protein diet or increased catabolism (fever, major illness, stress)
Discuss ideas states and disorders associated with urea measurements in renal causes
-decreased renal function causes increased blood urea due to poor excretion. Examples: acute & chronic renal failure, glomerular nephritis, tubular necrosis (caused by a lack of oxygen to the kidneys - ischemia )
Discuss ideas states and disorders associated with urea measurements in post-renal causes
-Obstruction of urine flow (renal calculi), tumor of bladder or prostate, severe infection
decreased urea nitrogen
-low protein dietary intake
-liver disease (lack of syntheis)
-Severe vomiting and/or diarrhea (loss)
-Increase protein synthesis
Creatinine is synthesized in
liver
creatinine is converted to creatine phosphate for
high energy source for muscle tissue
Discuss ideas states and disorders associated with urea measurements in decreased formation (liver disease)
Discuss ideas states and disorders associated with urea measurements in over-hydration: dilution
Discuss ideas states and disorders associated with urea measurements in end stage renal disease
Explain the chemical structure, synthesis and mode of excretion of creatinine
State the principle of the chemical reaction, sample types required, reference interval, most common interfering substances/ source of error, and the usefulness of the creatinine assay
State the reference range and explain the usefulness of the BUN/Creat ration
Discuss disease states and disorders associated with creatinine measurements especially in Muscle wasting disease
Discuss disease states and disorders associated with creatinine measurements especially in Renal disease
Use protocol for performing creatinine clearance test
Calculate creatinine clearance results using body surface area normalization
Recognize factors that can influence eGFR results (age, muscle mass, gender, race)
Explain the chemical structure, synthesis and mode of excretion of uric acid
