Liver tests (not done) Flashcards
Liver Biochemical Tests:
1) What are they also called?
2) What do they do?
3) Which name is older and a misnomer? Explain
1) AKA “Liver function tests” (LFTs), liver panel, hepatic panel
2) Assess the health/condition of the liver
3) LFTs; many do not accurately show how well the liver is functioning, can be abnormal in non-liver diseases, and can be normal in patients with advanced liver disease
List what’s in a BMP
1) Electrolytes: Na+, K+, Cl-, CO2 (HCO3-), Calcium (total)
2) Glucose
3) Kidney function: BUN, Creatinine
List the liver tests included in a CMP
1) Liver enzymes: ALT, AST, ALP
2) Protein: Total, Albumin, Globulin, ratio
3) Bilirubin (total and direct)
1) What is CMP?
2) What are some other liver-related tests (not all on CMP)?
1) BMP + most common LFTs = CMP
2) GGT, LDH, PT, AFP, Urea/Ammonia
Give examples of disorders that involve the liver
Various infections, fatty liver disease, heart failure, metastatic carcinoma
don’t need to know these specifically
Alanine Aminotransferase (ALT):
1) What was it formerly called?
2) What is it?
3) Where is the highest concentration?
4) What does it test for? What is its sensitivity and specificity?
1) Formerly serum glutamic pyruvic acid (SGPT)
2) Enzyme that is released when there is damage to liver, kidneys, heart, skeletal muscles
3) Highest concentration in the liver (most elevations are due to liver disease)
4) Very sensitive and specific for liver disease
Aspartate Aminotransferase (AST)
1) What was it formerly called?
2) What is it? Where is it found?
3) Where is the highest concentration?
4) What does it test for? What is its sensitivity and specificity compared to ALT?
1) Serum glutamic-oxaloacetic transaminase (SGOT)
2) Another transaminase enzyme
-Liver, heart, skeletal muscles, kidneys, brain, pancreas, spleen, lungs, WBCs/RBCs (in order of decreasing concentration)
3) Liver
4) Less specific than ALT for liver disease; usually more elevated than ALT in liver cirrhosis and alcoholic hepatitis
Alkaline Phosphatase (ALP/ alk phos):
1) What is it important for? Where is the highest concentration?
2) What is it used to diagnose?
3) What is it the most sensitive test for?
1) Important for lipid transport and bone calcification
-Liver, biliary tract, and bone
2) Liver and bone disorders
3) Metastasis to liver
1) Define total protein
2) What makes up 60% of total protein? What does it do?
1) Albumin and other proteins (globulins) including antibodies
2) Albumin: Maintains intravascular osmotic pressure; transports blood constituents like drugs and hormones
Albumin:
1) Where is it made? When is it decreased?
2) What is its half life? What does this imply?
3) Is it a reactant?
1) Liver (measure of liver biosynthetic ability); markedly decreased with hepatocellular dysfunction
2) Long half-life (12-18 days): detection of low albumin can be delayed after disease onset
3) Negative acute phase reactant
Globulin:
1) What is it?
2) Give examples
1) All non-albumin proteins
2) Alpha, beta, and gamma (e.g., antibodies) globulins
1) True or false: Different diseases have different combinations of increased/decreased proteins
2) What happens when the liver can’t make enough albumin?
3) What will lead to a totally normal protein despite some abnormalities?
1) True
Example: chronic liver disease
2) Reticuloendothelial system makes more globulins (to maintain normal total protein)
3) Low albumin, high globulin = normal total protein
1) What is a liver related ratio usually included on the liber panel?
2) What should it be?
3) What do decreased values suggest?
1) Albumin/globulin ratio; usually included on liver panel
2) >1.0 (e.g., more albumin than globulins)
3) Underlying disease that selectively decreases albumin
Protein electrophoresis:
1) What is it?
2) What can it be done on?
3) What is the normal SPEP pattern?
1) Electric field separates proteins according to their charge, size, and shape
2) Can be done on serum (SPEP) or urine (UPEP)
3) Peaks for albumin (largest peak) and globulins: alpha (1 and 2), beta (1 and 2), and gamma
SPEP & IFE: Polyclonal vs. Monoclonal Gammopathy:
1) What does polyclonal mean? What is it associated with?
2) What about monoclonal?
1) Multiple cell lines
-Infections/ inflammatory process
2) One cell line replicated; monoclonal (M) protein
-Usually neoplastic (e.g., multiple myeloma)
A 70-year-old male presents to your primary care clinic for evaluation of progressive low back pain, fatigue, and weight loss over the past several months. Labs are performed showing an elevated creatinine, anemia, and hypercalcemia. Multiple myeloma is suspected, and additional work up is ordered, including ЅΡΕР and UΡEР with immunofixation.
Which of the following SPEP/UPEP findings would be most consistent with this suspected diagnosis?:
Many small peaks of different proteins
Tall narrow peak of a single protein
Normal SPEP/UPEP
Decrease in albumin with no changes in amount of other proteins
Tall narrow peak of a single protein
Name a product of heme breakdown (primarily from Hgb). What is it a component of?
Bilirubin; one of the many components of bile (along with salts, phospholipids, cholesterol, bicarb, water)
Bilirubin Metabolism: #1: Spleen
1) What is the first step of the spleen’s metabolism of bilirubin?
2) What is heme then metabolized into? Where does it go?
1) Hgb released from RBCs
Broken into heme and globin molecules
Heme > metabolized into unconjugated (indirect) bilirubin (lipid soluble)
2) Binds to albumin; cannot be filtered by kidney (not in urine)
Bilirubin Metabolism: #2: Liver
1) Uptake: unconjugated bilirubin-albumin complex travels to liver > bilirubin dissociates from albumin and enters hepatocytes
Conjugation: unconjugated bilirubin + glucuronic acid combine (via hepatic glucuronosyltransferase) > conjugated (direct) bilirubin (water soluble)
Bilirubin Metabolism: #2: Liver
1) Where/ how is bilirubin excreted by the liver?
2) Why is this step notable?
1) Hepatocytes excrete conjugated bilirubin into bile
2) Rate limiting step of liver bilirubin metabolism
if excretion is impaired, conjugated bilirubin enters hepatic sinusoids and then bloodstream (conjugated hyperbilirubinemia)
Bilirubin Metabolism: #3: Bowel & Kidney
1) What happens to conjugated bilirubin in bile?
2) What allows it to be excreted? What is the alternative?
3) What can be reabsorbed in the intestine and enter portal circulation?
1) Travels through biliary ducts to duodenum:
2) Unchanged in stool or converted to urobilinogen by bacteria in colon
3) Urobilinogen
If conjugated bilirubin cannot be excreted into the intestine due to extrahepatic obstruction, what would this lead to?
Light stools (“clay colored”) [lack of stercobilin] and conjugated hyperbilirubinemia
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1) Conjugated bilirubin is filtered by what?
2) Is it normally detectible?
3) What causes dark, tea-colored urine?
1) Kidney (excreted in urine)
2) Normally should be undetectable (only small amount) in urine
3) When there is conjugated hyperbilirubinemia, levels in urine are increased
What happens to urobilinogen during bilirubin metabolism?
Can be reabsorbed in intestine (enters portal circulation):
1) some is taken up by liver and re-excreted in bile
2) some bypasses the liver and is excreted by kidney (small amounts in urine)
3) some is converted to stercobilin in bowel (turns stool brown)
