Liver Enzymes and More

What is the liver?

What is the liver?

Largest organ in the body. Has 2 lobes (right and left)

What is the purpose of the liver lobules?

Functional unit of the liver. Each contains a central vein.

What are hepatocytes?

perform major functions of liver and have regenerative properties

What are kupffer cells and what system are they part of?

phagocytic cells that detox liver. They are part of the reticuloendothelial system

define glycogenesis

glycogen production

define glycogenolysis

degrading glycogen

What is gluconeogenesis?

production of glucose from noncarbohydrate sources

Where are most proteins synthesized? What are the different components?

the liver. more specifically coagulation factors, transferrin, haptoglobin, acute phase reactants, and albumin

What are two proteins not synthesized in the liver?

adult hemoglobin and gamma globulin

What is the function of albumin?

nutrition, oncotic pressure, transport

Where are lipids synthesized and why are they created?

synthesized in the liver in response to excess carbohydrate intake

How are bile acids produced?

produced by the breakdown of cholesterol and collected in the biliary canaliculi before being stored in the gall bladder

What is bilirubin metabolism?

breakdown of heme

What organ that eliminates heme (blood) waste products?

the liver. makes bilirubin water soluble and able to excrete through bile duct

what does the liver detoxify?

xenobiotics (compounds foreign to the body)

What substances does the liver remove?

ammonia, bilirubin, hormones, drugs

What does the liver store?

iron, glycogen, amino acids, some lipids (triglycerides), vitamins (fat soluble, A, D, E, K)

What the only direct test of liver function?

bilirubin test

What are other (indirect) tests for liver function?

protein (albumin and alpha-1-antitrypsin), prothrombin time (clotting time), lipids (used as a risk assessment for arteriosclerosis)

Glucose is regulated by what two hormones? Where are those hormones produced?

insulin and growth hormone are produced in the pancreas

ammonia levels used to diagnose what?

hepatic coma and reye's syndrome

How are enzymes important when it comes to cell damage?

cell damage leads to an increase of proteins. The activity of this is associated with disease because they are located within the cell.

Which enzymes used in evaluating liver disease?

alkaline phosphate (ALP), gamma-glutamyl transferase (GGT), lactate dehydrogenase (LD), aspartate aminotransferase (AST), alanine aminotransferase (ALT)

What are alkaline phosphate (ALP) levels used for?

evaluating obstructive jaundice

What are gamma-glutamyl transferase levels used for?

most sensitive indicator of hepatocellular damage, used to evaluate alcoholism

What are alanine aminotransferase used for?

liver specific transaminase

altered bilirubin metabolism causes what?

ascites, jaundice

What is ascites?

accumulation of fluid in peritoneal cavity, causing abnormal swelling. most common cause is cirrhosis of the liver

How is jaundice caused?

excess deposits of bilirubin in skin and mucous membranes. also will accompany an icteric specimen

What is cholestasis?

when the flow of bile from liver is reduced or blocked

hepatic and post hepatic jaundice is caused by what?

disturbance in excretion of bilirubin

How is hemolytic disease connected with excess bilirubin?

due to excess excess bilirubin presented to liver. Will increase total total bilirubin, increase unconjugated bilirubin, conjugated bilirubin is normal.

How does post hepatic obstruction occur?

blockage of flow of bile into intestine. increases total bilirubin. Usually normal unconjugated, conjugated bilirubin increased

What is hepatic jaundice?

intrahepatic problem, hepatocellular damage, liver cell destruction

newborn jaundice caused by what?

impairment in esterification. UDP glucuronyl transferase enzyme system is not completely developed at birth

What is the time needed for infants to develop UDP glucuronyl transferase enzyme system

3 - 6 days after birth in full term infants. newborns with jaundice is aggravated in preterm infants. bilirubin levels usually do not exceed 10.0 mg/dl

hemolytic disease of newborn caused by what (liver)?

impairment in esterification

iso-immune hemolytic disease caused by what?

Rh, ABO, or other blood incompatibility with mother

How does hemolytic disease is dangerous in newborns affect bilirubin levels in the liver?

too much bilirubin on their livers can cause bilirubin plasma levels to rise quickly. Unbound bilirubin enters brain and binds to basal ganglia causing irreversible damage

Define Kernicterus

abnormal accumulation of bilirubin in newborns. can cause cell damage and death.

What is a critical value of bilirubin in newborns?

20.0 mg/dl (kernicterus)

How is newborn hemolytic disease treated?

UV light therapy

what pathway is affected by genetic defects of bilirubin metabolism?

metabolic pathway of transport and excretion in the hepatocyte

define Dubin-Johnson syndrome

defect in transport system for excreting bilirubin diglucuronide into the bile canaliculi

What is Crigler-Najjar syndrome?

absence or decrease in UDP glucuronyl transferase, very elevated levels of total bilirubin

Define Gilbert's disease

congenital malfunction of the transportation of bilirubin into the hepatocyte. estimated up to 10% of population

What is cirrhosis characterized by? (physically on the liver)

nodules in liver with fibrosis

define hepatitis

inflammation of the liver

What is hepatitis A?

a Fecal-Oral Virus

how is Hepatitis B transmitted?

parental/sexual

How is Hepatitis C tranmitted?

transmission = parental/sexual

How can someone get Hepatitis D?

this occurs only in combination with HBV

How is hepatitis E transmitted?

transmission = enteric

What are the clinical abnormalities of hepatitis

most cases do not result in noticeable jaundice. classification is based on serological testing

How are serological markers useful when it comes to hepatitis?

test that detects the hepatitis antigen/antibodies that are produced in response to hepatitis

what lab department does serological marker testing?

immunology or chemistry

What is the etiology of Reye's syndrome?

occurs in ages 2 to 13 , follows viral illness, actual cause is unknown

What does the fatty infiltration of liver in Reye's syndrome cause?

mitochondria dysfunction

What lab findings are attributed to Reye's syndrome?

increased ammonia, prognostic significance, prolonged prothrombin time

How quickly must a bilirubin test be done?

STAT

What tests are part of the liver panel?

total and direct bilirubin, AST, ALT, ALK, GGT

Which enzymes that are elevated in most liver dieases?

ALT > AST, AST, alkaline phosphorus, GGT

ALT is greater than AST in what disease?

acute liver disease (hepatitis)

Jendrassik-Grof method is used for what?

Used to test bilirubin. Avoid hemolysis. Light sensitive. Turbidity may affect result.

How are total and/or direct measurement of bilirubin used>

used for newborn jaundice. Must be less than 1 month old (lipochrome pigment can degrade overtime). Direct measurement at 455 nm and 575 nm.

What are the different methods to measure direct bilirubin?

Diazo methods, Jendrassik-Grof (most advantageous), vitros (dry slide chemistry), cationic polymer

total bilirubin equation

conjugated + unconjugated bilirubin = total bilirubin

indirect bilirubin equation

total - direct bilirubin = indirect bilirubin

what are critical values for newborn bilirubin?

15.0 mg/dl