Renal and Liver Function Tests Flashcards
measures the amount of nitrogen contained in the urea. It is the end
product of protein metabolism
BUN test
Produced entirely by the liver and eliminated by the kidneys
BUN
T/F: BUN test may be a marker of renal function.
True
High level BUN may indicate:
- _________ renal function
- _________ bleeding
- increased _______
- decreased
- upper GIT
- protein intake
Low level BUN may indicate:
- increased _________ status
- end-stage _________ disease
- hydration
- liver
With normal kidney function, the amount of __________ in the blood remains relatively constant and normal
creatinine
It is a function of muscle mass,
Creatinine clearance
It is filtered in glomerulus, but not re-absorbed or secreted
Creatinine clearance
is an adequate reflection of glomerular filtration rate (GFR)
creatinine clearance
most commonly used formula to
approximate renal function
Cockcroft and Gault formula
Another means of approximating renal function is the
24-hour urine collection
Comprised of seven most commonly ordered labs
Basic Metabolic Panel
requires a blood sample to measure the amount of urea in the blood stream and two urine specimens, collected one hour apart, to determine the amount of urea that is filtered, or cleared, by the kidneys into the urine.
Urea clearance test:
a measurement of the number of dissolved particles in urine. The test may be done on a urine sample collected first thing in the morning, on multiple time samples, or on a cumulative sample collected over a 24-hour period.
Urine osmolality test
Found abundantly in heart and liver tissues
Aspartate Aminotransferase (AST)
Used in clinical practice to:
- evaluate myocardial injury
- diagnoses and assess hepatocellular injury
Aspartate Aminotransferase (AST)
Significant elevations of AST may be due to
viral hepatitis and acute exposure to hepatotoxins
Moderate increase of AST may be due to
intrahepatic cholestasis or post-hepatic jaundice
T/F: ALT is also found abundantly in heart and liver tissues like AST
True
T/F: ALT is more abundant in liver than AST because it is more liver-specific enzyme
True
AST>ALT in
cirrhosis
AST»>ALT
myocardial injury
increased due to intra-hepatic or post-hepatic biliary obstructio
Liver-derived Alkaline Phosphatase
- increased due to Paget’s disease
- increased due to cancer bone metastasis
Bone-derived Alkaline Phosphatase is produced by osteoblast
80% of serum colloid oncotic pressure
Albumin
Hypoalbuminemia may occur due to
malnutrition,
hepatic insufficiency, or nephrosis
Low albumin may lead to
edema or transudation of ECF
Bilirubin clinical significance
Elevates (indirect): liver damage, hemolytic anemia
Elevated (direct): biliary obstruction
Sum of conjugated and unconjugated forms
Total Bilirubin
Originates as a breakdown product of hemoglobin degradation
Total Bilirubin
Enters the blood from the RES primarily attached to serum albumin
Indirect Bilirubin
Small fraction of bilirubin circulates thru the bloodstream in an unbound or free form
Indirect Bilirubin
This free bilirubin is not water soluble
Indirect Bilirubin
Upon arrival at the sinusoidal surface of the liver cells, the free bilirubin is rapidly taken up into the cell
Indirect Bilirubin
Once it enters the liver, the free bilirubin undergoes conjugation thru a
process known as glucoronidation
Direct Bilirubin
excretable
Direct Bilirubin
Is excreted in bile
Direct Bilirubin
May be excreted in urine if serum [DB] > 0.2 – 0.4 mg/dL
Direct Bilirubin
Hyperbilirubinemia may be due to the increases in indirect bilirubin such as
hemolysis
- hepatocellular damage, due to an inability to conjugate
Hyperbilirubinemia may be due to the increases in direct bilirubin such as
post-hepatic cholestasis
