Liver Function

Question 1

What are the functions of the liver?

Answer 1

Protein metabolism
Carbohydrate metabolism
Lipid metabolism
Storage function (glycogen, triglycerides, iron, and copper)
Detoxification
Mononuclear phagocyte system through Kupffer cells
Excretory function

Question 2

What is bile acids dependent?

Answer 2

BA excretion increased water excretion due to osmotic gradient

Question 3

What is BA independent?

Answer 3

Active transport Na, glutathione, and HCO3; promote bile formation

Question 4

How does secretin promote bile formation?

Answer 4

By stimulating HCO3 and Cl secretion into bile

Question 5

What are the components of bile?

Answer 5

H2O
BA
Conjugate bilirubin
Lecitin
Cholesterol
Fatty acids
Electrolytes
Water soluble wastes

Question 6

What are abnormal CBC results due to hepatic insufficiency or disease?

Answer 6

Acanthocytosis
Anemia
Codocytosis
Microcytosis

Question 7

What are abnormal chemistry assays due to hepatic insufficiency or disease?

Answer 7

Decreased BUN
Hyperammonemia
Hyperbilirubinemia
Hyper/Hypocholesterolemia
Hyper/Hypoglycemia
Hyperuricemia
Hypoalbuminemia
Hypoproteinemia
Hypofibrinogenemia
Increased ALT, AST, LD, ID, GMD, AST, GGT
Lipemia

Question 8

What are abnormal UA results due to hepatic insufficiency or disease?

Answer 8

Ammonium biurate crystalluria
Bilirubinuria
Hyposthenuria
Isosthenuria

Question 9

What are other abnormal lab results due to hepatic insufficiency or disease?

Answer 9

Prolonged PTT, PT
Ascites
Steatorrhea

Question 10

What is hepatic insufficiency?

Answer 10

Pathophysiological state where there is a marked reduction on functioning hepatocytes numbers

Question 11

What is cholestasis?

Answer 11

Stoppage or suppression of bile flow

Question 12

What causes stoppage of bile flow?

Answer 12

Distended bile ducts and bile plugs

Question 13

What causes suppression of bile flow?

Answer 13

Decreased BA secretion

Question 14

What is icterus caused by?

Answer 14

Hyperbilirubinemia

Question 15

What causes obstructive biliary disease?

Answer 15

Decreased Bc and BA excretion

Question 16

What does bilirubin come from?

Answer 16

Heme

Question 17

What does BA come from?

Answer 17

Cholesterol

Question 18

What are the 3 type of bilirubin in the plasma?

Answer 18

Unconjugated bilirubin (Bu) bound to albumin
Conjugated bilirubin (Bc)
Conjugated bilirubin bound covalently to albumin (δ)

Question 19

What is bilirubin cleared by?

Answer 19

The liver or kidneys

Question 20

In what species is small amounts of bilirubin commonly present in urine?

Answer 20

Dogs

Question 21

What can bilirubin be measured by?

Answer 21

Wet colorimetric assay or dry chemistry

Question 22

How is [Bt] calculated with wet colorimetric?

Answer 22

[Bc] + [Bδ] + [Bu]

Question 23

How is [Bc] calculated with wet colorimetric?

Answer 23

[Bc] + [Bδ]

Question 24

How is [Bu] calculated with wet colorimetric?

Answer 24

[Bt] - [Bc]

Question 25

How is [Bδ] calculated?

Answer 25

Only from dry chemistry | [Bt] - [Bu] - [Bc]

Question 26

How do you calculate Bt with dry chemistry?

Answer 26

[Bu] + [Bc] + [Bδ]

Question 27

What are causes of hyperbilirubinemia?

Answer 27

Increased Bu production (prehepatic) Decreased uptake by hepatocytes (hepatic) Obstructive cholestasis (posthepatic) Functional cholestasis (posthepatic)

Question 28

What are the findings associated with increased Bu production?

Answer 28

``` Bt may be markedly increased Early: [Bu] > [Bc] Later: [Bu] = [Bc] Regenerative anemia Hemoglobinuria or hemoglobinemia Bilirubinuria ```

Question 29

What are the non-hemolytic increased Bu production?

Answer 29

Ineffective erythropoiesis Destruction of myoglobin Cytochromes Peroxidases

Question 30

What are causes of decreased uptake by hepatocytes associated with hyperbilirubinuria?

Answer 30

Fasting hyperbilirubinemia: Horses that are off feed Anorexic cattle with rumen stasis Decreased functional hepatic mass

Question 31

What causes impairment of bile flow?

Answer 31

Hepatocellular swelling Periportal lesions that compress bile ducts Other process that damage or compress bile ducts (infection, neoplasia, etc.)

Question 32

What is the cause of functional cholestasis?

Answer 32

Impaired excretion of Bc without biliary obstruction

Question 33

What is an additional finding with functional cholestasis?

Answer 33

Inflamamtory leukogram

Question 34

What happens to most of the bile acids secreted in the intestines in healthy animals?

Answer 34

Resorbed by the intestines and reuptaken by hepatocytes

Question 35

What may happen after intestinal resorption of BA?

Answer 35

It may overwhelm the liver's ability to uptake causing postprandial increased in [Ba]

Question 36

What assay is used to measure bile acids?

Answer 36

Colorimetric assay

Question 37

What are the 2 major pathologic processes of increased bule acids?

Answer 37

Decreased BA clearance from portal circulation | Decreased biliary excretion of BA

Question 38

What causes decreased BA clearance from portal circulation?

Answer 38

Decreased hepatic function caused by any mechanism

Question 39

What causes decreased biliary excretion of BA?

Answer 39

``` Hepatic or posthepatic cholestasis by any mechanism Hepatocytes may pump BA in sinusoidal circulation (regurgitation) Functional cholestasis (inflammatory cytokines) ```

Question 40

What are factors other than hepatobiliary that can change results of BA?

Answer 40

``` Fasting BA (spontaneous contraction of gallbladder, intestinal diseases) 2h postprandial ```

Question 41

What is the most common form of ammonium in plasma?

Answer 41

NH4, not NH3 (ammonia)

Question 42

Where can you get a sample of ammonium?

Answer 42

Plasma, not whole blood

Question 43

What can cause a false increase in NH4?

Answer 43

Hemolysis

Question 44

What are causes of increased ammonium?

Answer 44

Decreased clearance from portal blood Decreased clearance due to congenital diseases that involve the urea cycle Increased production Increased intake or absorption

Question 45

What are causes of decreased clearance from portal blood that causes an increase in ammonium?

Answer 45

Diffuse hepatocellular disease that reduces functional mass | Portosystemic shunts

Question 46

What are causes of an increased production of ammonium?

Answer 46

Urea toxicosis in cattle Strenuous exercise Urinary infection with urease-containing bacteria Intestinal diseases in horses

Question 47

What are causes of increased intake or absorption?

Answer 47

NH4Cl for ammonia tolerance test NH3 treated forage Malicious release of NH3 from storage tanks

Question 48

What is the ammonium toelerance test?

Answer 48

NH3Cl is administered to challenge removal from portal circulation and/or challenge to hepatocytes urea cycle

Question 49

When is the tolerance test not recommended?

Answer 49

If there is fasting hyperammonemia

Question 50

What does increased ammonium mean with the tolerance test?

Answer 50

Decreased functional hepatocyte mass or PSS