Liver and Pancreatic Disease Labs

Question 1

what are the common liver chemistries

according to ACG 2021: when do we work up a pt according to liver chemistries

Answer 1

• asparate aminotransferase (AST)
• alanine aminotransferase (ALT)
• gamma glutamyl transpeptidase (GGT)
• alkaline phophate (alk phos, AP)
• albumin
• PT (prothrombin)
• LDH (lactate dehydrogenase)

When to Work up
- work up even moderate/mild elevations in the chemistries; if no cause found watch/wait or refer
- all moderate/severe elevation require prompt evaluation to hepatologist who may biopsy
- if signs of liver failure (jaundice, ascites, puritis, AMS)= urgent eval

Question 2

what is the AST/ALT
where are each found
what do they indicate

Answer 2

AST
- from the liver, cardiac muscle, kidney & skeletal muscle
- when hepatocytes are inflammed within the liver: the AST is leaked out: thus we get an elevation in lab values
- when AST is elevated much more than ALT think alcohol related disease

ALT
- more specific than AST to the liver;but stil found in cardiac/skeletal muscle, kidneys, brain and RBCs
- when hepatocytes are inflammaed; ALT is spilled out
- when ALT is elevated much more that AST: think of viral hepatitis
- the ALT can elevate with an increase in BMI

new ULN proposed in healthy BMI individuals
- 29 for men, 22 for women

GGT elevated tied to increased mortality risk too

Question 3

the use of GGT & Alkaline Phosphate

Answer 3

Alkaline Phosphate
- comes from the liver, bone, placenta, intestines and kidneys
- elevated levels also if there is a bile obstruction
- see increase in kids (bone growth) and pregnant women (placenta)

to differentiate if the alk phos elevation is coming from the liver….

GGT is used
- from hepatocytes, billiary epithelial cells
- when elevated AP and elevated GGT: indicates a hepatobilliary process is the most likely cause
- can be elevated with alcohol, phenytonin or barbituates

Question 4

Role of Albumin, PT and billirubin in liver chemistries

Answer 4

Albumin
- a marker of liver function as albumin is made in the liver ONLY

PT
- a measure of the extrinsic pathway and vit K dependent factors
- measures more acutely the function of the liver
- but, the changes usually are a result of severe damage

Bilirubin
- marker of heaptobillary function
- cmes from enterohepatic circulation, some from intestines/urine
- direct (conjugated) and indirect (unconjigated)
- reported as a total bili
- elevated tbili indicates hepatocellualr or cholestasis

Question 5

Hepatocellular Pattern of Liver Function Tests

• what is is
• some conditions
• severity classes
• use of the AST/ALT ratio

Answer 5

elevated AST/ALT more than the alk phospahte indicates its a hepatocellular dysfunction

think of conditions which are directly impacting the liver and its ability to function
- NAFLD
- alcoholic liver disease
- hep B/C chronic
- drug induced liver (tylenol!!)
- autoimmune hepatitis
- wilsons disease
- biliary cholangitis
- sclerosing cholangitis

Severity
mild = 2-5x ULN : work-up then wait or refer
moderate = 5-15x ULN : work-up then refer if no findings
severe = 15x ULN : workup (include thombosis for budd-chaiari, tox screen for ASA) then refer for biopsy
massive = > 10,00 x ULN : workup (include toxicity, ischmic and rhabdo. first) then other tests, thenrefer for biopsy is stable (if acute signs if liver faiure: urgent eval)

AST/ALT Ratio
- if the AST > ALT by a 2:1 ratio = think alcoholic liver disease (unless ALT >500)
- if AST/ALT ratio < 1 = viral, acute/chronic liver injutry, NAFLD

Question 6

Cholestatic Pattern of Liver Chemistries
- pattern
- disease processes

Answer 6

a predominant elevation of the alkaline phosphate more than the AST/ALT

if alk phosphate elevate: get GGT!!! to see if its a liver process

if GGT +
- choleductolithiasis
- primary choleangitis
- malignancy

if GGT is -
- pirmary sclerosing choleangitis
- cholestasis of pregnancy
- infilterative process (TB, sarcoid, amylodosis)

Question 7

Equation to differenitate between cholestatic, hepatocellular or mixed disease

Answer 7

R = (ALT value/ALT ULN)/(Alk phos valve/alk phos ULN)

if R….
R < 2 = cholestatic
R = 2-5 = mixed
R > 5 = hepatocellular

Question 8

Isolated hyperbilirubinemia
- conditions to think of if conjugated v unconjugated

Answer 8

if ONLY bili is elevated — assessif its unconjugated (before the liver issue) or conjugated

predominant unconjugated
- hemolysis
- Gilbert Syndrome
- Crigler-Najjar Syndrome

predominantly conguated
- Dubin-Johnsn
- Rotor syndrome

Question 9

Additional Liver Chemistries

Aldolase

LDH

Blood Ammonia

Answer 9

Aldolase
- testing for organ/muscle damage as a result of organ damage
- not specific: hepatitis, skeletal muscle damage, MI, cancer, muscle disease, mono

LDH: lactate dehydrogenase
- present in most body tissue
- elevated due to: liver disease, MI, anemia, fracture, cancer, meningitis, HIV

Blood Ammonia
- elevated in: liver failure (inability to detoxify), reye syndrome (pedatric liver failure due to asprin)

Question 10

Calculations for Liver Diseases

Answer 10

METAVIR: a quantitative score for NAFLD

MELD: end-stage liver disease: transplant need

Child-Pugh: drug dosing guidance

Question 11

Pancreatic Labs

Amylase

Lipiase

Trypsinogen Activation Peptide

Answer 11

Amylase
- highly sensitive: but not specific to the pancreas if elevated
- conditions: pancreatitis, pancreatic CA, bile duct dtone, salivary stone, post-ERCP, bowel perf, peptic ucler penitration, etopoic preg, DKA, renal failure

Lipase
- more specific to the pancrease
- conditions: acute pancreatitis, chronic pancreatitis, pseudocyst, billary disease, renal failure, bowl obstruction, sailvary galnd, pregnant, peptic ucler

Trypsinogen Activation Peptide
- new; early acute pancreatitis dx.

Question 12

other labs within acute pancreatitis

Answer 12

• leukocytosis
• hematocrit
• BUN
• hypocalcemia
• hyper/hypoglycemia (hyper early then hypo)