Bile Acids and Liver Function

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Questions and Answers

What does an increase in conjugated bilirubin levels typically indicate?

Cholesterol metabolism efficiency

Excessive liver production of bile acids

Bile duct obstruction (correct)

High fat absorption capability

Which of the following conditions is least likely to cause elevated serum bile acid (SBA) levels?

Acute urinary tract infection (correct)

Hepatic cirrhosis

Chronic hepatitis

Congenital portosystemic shunts

What is the primary function of bile acids in the body?

Aiding in fat absorption (correct)

Enhancement of red blood cell production

Regulation of blood pressure

Stimulation of insulin production

How are bile acids primarily synthesized in the liver?

From cholesterol Signup and view all the answers

What percentage of bile acids is usually actively resorbed in the ileum?

90% to 95% Signup and view all the answers

Which scenario is most likely to lead to decreased serum bile acid levels?

Intestinal malabsorptive diseases Signup and view all the answers

What occurs to bile acids after they reach the ileum?

They are transported back to the liver. Signup and view all the answers

What is the primary purpose of bile acid testing?

As a screening test for liver disease Signup and view all the answers

Which enzyme is primarily found free in the cytoplasm of hepatocytes and signifies liver damage shortly after it occurs?

Alanine transaminase (ALT) Signup and view all the answers

What mechanism primarily leads to the presence of hyperammonemia?

Decreased functional hepatic mass Signup and view all the answers

What characteristic sets apart leakage enzymes from inducible enzymes in liver enzymology?

Leakage enzymes are free within the cytoplasm Signup and view all the answers

Which enzyme may increase in the blood due to liver damage as well as muscle inflammation or necrosis?

Aspartate transaminase (AST) Signup and view all the answers

In which animals is alanine transaminase (ALT) considered a liver-specific test?

Dogs, cats, and primates Signup and view all the answers

What is the main action of hepatocytes concerning ammonia generated in the intestinal tract?

Convert ammonia into urea Signup and view all the answers

What role does alkaline phosphatase (ALP) play among the liver enzymes?

It is a membrane-bound inducible enzyme Signup and view all the answers

What contributes to elevated ammonia levels in the blood, leading to conditions such as urea toxicosis in ruminants?

Ingestion of too much urea in the diet Signup and view all the answers

What is the primary function of the gallbladder?

Storage of bile Signup and view all the answers

Which condition is characterized by a decrease in albumin levels?

Hypoalbuminemia Signup and view all the answers

What does hyperbilirubinemia indicate?

Increased bilirubin in the blood Signup and view all the answers

Which test is commonly used to assess hepatocyte function?

Bilirubin measurements Signup and view all the answers

How is unconjugated bilirubin characterized?

It is bound to albumin Signup and view all the answers

What percentage of total bilirubin in serum is typically unconjugated?

Approximately two-thirds Signup and view all the answers

What can cause jaundice in patients with liver dysfunction?

Impaired hepatic cell metabolism Signup and view all the answers

What is a potential outcome of hepatic disease that affects metabolic processes?

Bleeding disorders due to hemostasis problems Signup and view all the answers

Which of the following is NOT typically a symptom of liver dysfunction?

Hyperglycemia Signup and view all the answers

Study Notes

Deceased Veterans Memorial

A memorial situated in a park-like setting
Constructed of light-colored stone, in a stepped or tiered design
Contains recessed circular openings with emblems or insignia
Dedicated to service members from the USA
Includes names of a number of individuals, along with their service information, rank, and dates of service.

Blood Chemistry Report

Includes a variety of blood chemistry results.
Results include values for Glucose, BUN, Creatinine, BUN:Creatinine ratio, Phosphorus, Potassium, Chloride, Total Protein, Albumin, Globulin, Alb:Glob Ratio, ALT, ALP, GGT, Bilirubin-Total, Cholesterol, SDMA, and more.
Results also provide references ranges.
Several of the values are abnormal compared to the reference range (e.g., abnormally high or low values).

Introduction to Proteins

Proteins are a crucial component of the plasma.
Mostly produced by the liver.
Can indicate how well the liver is functioning.
Protein concentration in disease conditions can alter.

Protein Functions

Structure of tissues, organs, cells.
Maintaining osmotic pressures.
Part of enzymatic biochemical reactions.
Buffers in acid-base balance.
Involved in blood clotting.
Defend against harmful microorganisms.
Transport molecules.

Total Protein

Includes fibrinogen
Serum protein content does not include fibrinogen.
Levels altered by factors such as affected hepatic synthesis, altered protein distribution/excretion and dehydration/overhydration.
Useful in determining hydration status, for patients with edema or ascites, loss of weight or diseases of the liver, kidneys or blood clotting problems.

Total Protein Testing

Two primary methods: Refractometer and Biuret.
Refractometer estimates refractive index of serum/plasma (fast, inexpensive, accurate)
Biuret measures molecules containing more than 3 peptide bonds (accurate)

Protein Analysis

Gel Electrophoresis
Salt fractionation
Chromatography
Used in research labs to separate protein populations.
Diagram of results from serum electrophoresis showing the albumin and three globulin peaks.

Albumin

One of the most crucial proteins in plasma/serum (makes up 35-50% in most animals).
Synthesized by hepatocytes (liver cells).
Important for osmotic pressure of plasma.
Decreased levels in liver disease, kidney or intestinal disease, or malnutrition.

Globulins

Alpha and Beta globulins primarily made in the liver, and transport proteins.
High-density lipoproteins (HDL)
Very low-density lipoproteins (LDL).
Beta globulins: include complement (C3, C4), transferrin, ferritin.
Gamma globulins (immunoglobulins).

Albumin/Globulin Ratio

Ratio is used in assessing protein abnormalities.
Used in conjunction with protein profile; most disease conditions alter this ratio.
Albumin greater than globulin in dogs, horses, sheep and goats (A/G > 1).
In cattle, pigs and cats, albumin is equal to or lower than globulins (A/G < 1).

Acute-Phase Proteins

Produced by the liver in response to injury or inflammation.
Include CRP, SAA, fibrinogen, and haptoglobin.
Albumin and transferrin concentrations decrease in response to acute-phase reactions.

Fibrinogen

Hepatocytes produce it.
Forms insoluble matrix of blood clots.
Reduced by liver disease.
Elevated levels associated with inflammation, bleeding or trauma.

Conditions Associated with Altered Serum Proteins

Elevated: hyperproteinemia, hemoconcentration, inflammatory disease, and plasmacytoma.
Decreased: hypoproteinemia, hypoalbuminemia, hemodillution, blood loss, glomerulonephritis, hepatic insufficiency, and malnutrition.

Hepatic Markers

Assess Liver function, examining different aspects of functionality.
Assess hepatobiliary clearance
Evaluate hepatic enzymes.
Review hepatic synthesis markers.

The Liver

Largest internal organ
Complex structure, function and pathologic characteristics.
Functions: metabolism, synthesis, digestion and absorption of nutrients, secretion of bilirubin and bile, elimination and detoxification.

Gallbladder

Closely associated with the liver (both in function and anatomy).
Primary function: bile storage.

Liver, Gallbladder Malfunctions

Causes: hyperbilirubinemia (jaundice), hypoalbuminemia, hemostatis problems, hypoglycemia, hyperlipoproteinemia, and hepatoencephalopathy.

Hepatobiliary Clearance Markers:

Evaluate the liver's ability to process and excrete substances
Important for diagnosing liver disease
Common markers include Bilirubin(conjugated and unconjugated), Bile Acids

Hepatobiliary Assays:

Multiple different function tests, over 100 tests to detect a problem.
No single tests is superior to others
Tests being developed to detect problems sooner.

Hepatocyte Function Tests

Primarily run in veterinary settings.
Essential tests include Bilirubin and Bile Acids.
Other tests (albumin and cholesterol) are less sensitive.

Bilirubin

Elevated levels often indicate liver damage or obstruction of bile ducts.
Unconjugated bilirubin is found bound to albumin.
Conjugated bilirubin results in jaundice.

Bile Acids

Serve multiple functions, aiding in fat digestion and absorption and regulating cholesterol levels.
Synthesized in the liver from cholesterol.
Conjugated with glycine or taurine.
Primarily reabsorbed in the ileum (90-95%).

Ammonia

Generated by bacteria in the intestines.
Absorbed to the liver, converted to urea and cleared by kidneys.
Elevated ammonia levels (hyperammonemia) can harm the body.

Liver Enzymology

Leakage Enzymes (released from damaged liver cells): ALT & AST
ALT elevated rapidly in hepatocyte damage
AST elevated more slowly in more severe liver damage
Inducible Enzymes; ALP & GGT
ALP elevated in obstructive liver disease
GGT elevated in a variety of disorders

Alanine Transaminase (ALT)

Major source is the hepatocyte
Found free in the cytoplasm.
Elevated levels occur within 12 hours after liver damage.
Often used in liver function diagnosis, however, not specific

Aspartate Transaminase (AST)

Found within hepatocytes (both cytoplasm and bound to mitochondrial membrane).
Requires more severe liver damage to be released
Elevated levels occur more slowly and returns to normal quicker than ALT.

Iditol Dehydrogenase (SDH)

Primarily found within hepatocytes
Also found within kidneys, small intestines and RBCs.
Useful in diagnosis of liver disease in animals.
Not readily available for veterinary testing

Alkaline Phosphatase (ALP)

Present in hepatocytes, osteoblasts, chondroblasts, intestines and placenta, liver cells.
Significant increase in cholestasis in animal patients

Gamma Glutamyl Transpeptidase (GGT)

Found in numerous tissues; liver being the primary source.
Elevated GGT levels found in various animals (Horses, Sheep, Goat).
Elevated levels generally associated with liver disease, particularly obstructive liver disease.

Markers of Hepatic Synthesis

Liver responsible for synthesizing various components.
Markers include BUN levels, glucose concentrations, cholesterol, albumin/globulin levels and coagulation factors.

Hepatic Synthesis

Synthesis of crucial components (BUN, Glucose, Cholesterol, Albumin/Globulin, Coagulation factors) occurring through liver cells.

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Description

This quiz covers key concepts related to bile acids, their synthesis, function, and associated clinical conditions. Test your knowledge on topics such as bilirubin levels, serum bile acid elevations, and the resorption of bile acids in the ileum. Perfect for those studying liver function and biochemistry.