LIVER FUNCTION TEST

[ ] BIOCHEMICAL FUNCTIONS
[ ] CLINCAL SIGNIFICANCE
[ ] LABORATORY METHODS
[ ] REFERENCE VALUES

OBJECTIVES
 Describe the anatomy and function of the liver
 Discuss the most common liver function test used in
the clinical laboratory
 Identify Clinical manifestations of liver disease and
their disease pattern
 Discuss briefly hepatitis

LIVER
 Liver is the largest and most complex internal organ
 All blood flow from intestine and pancreas reaches
liver via venous system
 A multifunctional organ that is involved in diverse
body functions
 Primarily gastrointestinal

FUNTIONAL UNITS OF THE LIVER

 Lobules – made up of hepatocytes

Normal

 Bile ductus – series of ducts form the common hepatic

duct
o Bile canaliculi
o Canals of hearing
o Interlobular bile ducts
o Intrahepatic bile ducts
o Left and right hepatic ducts
 FUNCTIONS OF THE LIVER  To assess all functional capabilities of the liver such
 Metabolic as:
o Carbohydrate metabolism o Its Synthetic abilities:
o Gluconeogenesis  Plasma proteins such as albumin
o Glyconeogenesis  Prothrombin
o Hormone metabolism  Lipids
o Synthesis of FA, LPP, cholesterol o Its Secretory/Excretory abilities:
o Ketogenesis  Bilirubin
o Protein metabolism
o Synthesis of plasma proteins COMMON TESTS
o Urea synthesis  Liver enzymes
o Red blood cell production o AST ( ↑ alcohol consumption)
 Storage o ALT (Canaliculi damage)
o Glycogen o ALP (Canaliculi damage)
o Vitamin ADEK, B12 o CGT
o Iron  Serum BILIRUBIN
o Copper  Total protein, albumin, and globulin ratio (TPAG)
 Excretory and secretory  Prothrombin time
o Bile  Hepatitis profile
o Insulin like growth factor 1
o Most blood proteins are synthesized in the
liver
o Cholesterol, FA (via lipoproteins)
 Protective
o Purification, Transformation and Clearance
(ex. Ammonia)
o Kupffer cells – ingest bacteria or other
foreign bacteria from the blood
 Circulatory
o Called “Antechamber of the heart” because it
collects and processed al the portal vein and
delivers into the right side of the heart. The
liver receives blood through two vascular
systems, the portal vein and hepatic vein
artery.
 Coagulation – production and secretion of
coagulation factors
o Fibrinogen LIVER ENZYMES
o Prothrombin II
o Factors V, VII, IX, X, XI TRANSAMINASES (AST/ALT)
o Protein C - Catalyze reversibly the transfer of an amino group of
o Protein S either aspartate (AST) or alanine (ALT) to alpha-
o Antithrombin ketoglutarate to yield glutamate plus the corresponding
ketoacid of the starting amino acid, i.e. oxaloacetate or
FUNCTIONS OF THE LIVER pyruvate, respectively.
 Metabolic - Require pyridoxal phosphate (vitamin B6) as a cofactor
 Storage - 17 to 47 hours half-life (at peak)
 Excretory and secretory - Up to 40 IU/L
 Protective - mAST- 87 hours half-life
 Circulatory
 ALT
 Coagulation
- Most liver specific
- Nonalcoholic, asymptomatic patients
- Hepatitis C infections (mild)
LIVER FUNCTION TEST
 AST
 Liver function test are a group of tests done to assess
- Monitoring therapy with potentially hepatoxic
the functional capacity of the liver as well as any
drug
damage to the liver cells.
  Impaired hepatic synthesis of ALT Methods to determine TOTAL PROTEIN
o Pyridoxine deficiency  Kjeldahl method
o Hepatic fibrosis - Standard reference method
o Cirrhosis - Based on the measurement of nitrogen content
 Hepatocellular injury  Biuret method
o Hepatitis - Most widely used
 AST>ALT initially - Requires atleast 2 peptide bonds and an alkaline
 ALT>AST prolong damage medium
 Alcohol-induced hepatocyte injury - Reagents: alkaline copper, Rochelle salt and NA&K
o Alcoholic hepatitis iodide
o mAST>AST  Folin-Ciocalteu (Lowry Method)
 DeRitis ratio, or 3-4:1 - Using phosphotungstomolybdic acid or phenol
 Vitamin B6 deficient (alcoholics) reagent
o Low ALT - Oxidation of phenolic compounds such as tyrosine,
 Chronic hepatocyte injury tryptophan and histidine to give a deep blue color
o Cirrhosis  Ultraviolet absorption
 ALT>AST - CHONs absorb light at 280 light at 280 nm and 210
 Fibrosis progresses AST>ALT nm
 End stage both low - Absorption at 280 nm is due to tryptophan, tyrosine
 Acute fulminant hepatic failure and phenylalanine
o (markedly high) AST: ALR ratio is often - The absorbance of CHONs at 210 nm is due t the
significantly >1 absorbance of the peptide bonds at that wavelength
 Electrophoresis
ALKALINE PHOSPHATASE - Quantification of specific proteins-based
- 3 days half-life - Migration of charges particles in an electric field
- Found in canalicular surface  Refractometry
- Marker for biliary dysfunction - Is an alternative test to chemical analysis of serum TP
- 45 to 115 IU/L - Based on measurement of refractive index
 Turbidometric and Nephelometric methods
GAMMA-GLUTAMYL TRANFERASE (GGT) - These methods utilize SSA and TCA
- Regulates the transport of amino acids across cell - Measurement depends on the formation of a uniform
membranes by catalyzing the transfer of glutamyl group fine ppt which scatter incident light in suspension
from glutathione to a free amino acid.  Salt fractionation
- 10x upper normal - Globulins can be separated from albumin by salting-
o Chronic cholestasis out procedures using sodium salts
 Primary biliary cirrhosis - Sodium sulfate-used for analysis
 Sclerosing cholangitis - The albumin remains in solution on the supernatant
- Chronic abuse of alcohol can be measured by any of the routine CHON
o 1 month elevation after abstinence methods.
o 28 days half-life
- 0 to 43 IU/L - Concentration of inversely proportional to the severity of
liver disease
5’NUCLEOTIDASE - Decreased serum concentration may be due to decreased
- Test for true liver function synthesis
- Distinguish between ALP - Can be measured by direct methods based on dye-
- It never increases when there is a presence of biliary binding property
obstruction. - Dye used: BCG, MO, HABA, BCP
- Reference value: 3.5-5.0 g/dL
- Increased serum albumin (hyperalbuminemia)
TPAG DETERMINATION o Severe dehydration
- Analysis of CHONs is important in assessing nutritional o Prolonged tourniquet application- artificial
status and presence of severe disease involving the liver, hyperalbuminemia
kidney, and BM.
- Fasting may not be required
- Hemolysis falsely elevate the TP
- Test for liver disease
 Methods to determine ALBUMIN CONJUGATION FUNCTION OF THE LIVER
 Hypoalbuminemia - decreased serum albumin  Bromsulfonthalein (BSP) Dye Test
1. Reduced synthesis o Brominated phenolphthalein. Detects early
- Chronic liver disease lesion in the liver and measures the liver’s
- Malabsorption syndrome ability to conjugate and remove foreign
- Malnutrition and muscle wasting disease substance in the blood and excrete through
2. Increased loss the bile.
- Nephrotic syndrome (20-30 g/day) thus o Most sensitive chemical indicator from liver
excretion is increased when the glomerulus impairment.
no longer functions to restrict the passage of o Normal value: <5%
CHON from blood  Indocyanine Green/Cardiogreen
- Massive burns o Patients undergo fasting  pre-injection
- Protein-losing enteropathy
sample (blank)  IV 0.5mg/kg body weight
- Orthostatic albuminuria
3. Increased catabolism dye  20 minutes  post-injection
- Massive burns sample805 nm
- Widespread malignancy
- Thyroxicosis DETOXIFICATION FUNCTION OF THE LIVER
 Analbuminemia – hereditary absence of albumin;  Hippuric Acid Test
inability to synthesize albumin o Benzoic acid in the form of sodium benzoate
 Bisalbuminemia – albumin that has unusual molecular is conjugated with the amino acid glycine in
characteristics the liver to produce hippuric acid for renal
o Presence if two albumin bands instead of the excretion.
single band in electrophoresis  Rosebengal
o Associated with the presence of therapeutic o It makes use of a dye which is tagged with
drugs in serum 125Iodine administered to the patient and the
 Determine A/G ratio tagged molecule are taken up by the
o TP-A = Globulin hepatocytes and the rate of the appearance of
o Albumin/Globulin ratio = 1.3-3:1 the radioactive molecule in the blood or the
o If the globulin is greater than albumin (inverted rate of the reaction is measured.
ratio) o Distinguish hepatocellular from obstructive
jaundice.
Rosenthal-White McDonalds’
Dose 2 mgs/kg body weight 5 mgs/kg body weight CLINICAL MANIFESTATIONS OF LIVER DISEASE
Formula Weights in lbs/55 Weights in lbs/22
 Jaundice
No. of Double Single
Collection  Portal hypertension: More than 20 mmHg pressure
Interpretation 5 minutes = 25-50% 45 minutes = less than causing obstruction in hepatic vein, leading to pressure
retained 5% is retained build-up.
30 minutes = all  Encephalopathy and hepatic failure; brain
excreted out
Specificity More Specific Less Specific
inflammation
 Liver damage: Altered drug metabolism
(accumulation in the liver)
PROTHROMBIN  Endocrine Abnormalities: Chronic liver disease,
Prothrombin Time (Vitamin K response test) increased estrogen level  feminization
 Prothrombin is a clotting factor (clotting factor II) and
it forms an important part of both the intrinsic and PATTERNS OF LIVER DAMAGE
extrinsic pathway.  Direct Pattern – Due to individual cell death in
 Its active form is Thrombin (also clotting factor IIa). It specific areas: chronic alcoholics were alcohol gives
is a serine peptidase which converts fibrinogen to oxidation production of ethanol (acetaldehyde) which
fibrin. destroys liver cells.
 Prothrombin is synthesized in the liver. And hence  Immunologically Mediated Hepatocyte Injury –
prothrombin activity in plasma is used to measure the More complex; some cytotoxic lymphocytes attacks
synthetic function of liver. cell membrane of liver cells due to antigen
 Differentiates intrahepatic (prolong PT) from recognition.
extrahepatic obstructive liver disease (normal PT)  Cholestatic Liver Injury – Due to extrahepatic
(tumor & obstruction) or intrahepatic obstruction
 (edema) due to functional disturbances in the bile - IgM anti-HAV (2-3 weeks)
secretory mechanism. o Increasing AST and ALT
o Up to 3-6 months
RELATED DISEASES IN LIVER FUNCTION - IgG antibodies (1-2 weeks of IgM antibodies)
 Chronic Hepatitis - PCR (stool and plasma)
 Alcoholic Liver Disease
o Laennec’s Cirrhosis; Zienne’s Syndrome Hepatitis B
(acute hemolysis; accumulation of serum - Hepadnavirus family
lipids) - DNA viruses
o CGT is 8-10x increased in heavy drinkers and - Body fluids
in liver disease. o Sex
 Drug-Induced Liver Disease – Acetaminophen and o Transplacental
isoniazid (hepatotoxins); hypersensitivity immune - Different groups of tests are recommended for three
reactions; unmonitored Tylenol intake different clinical situations as follows:
 Cirrhosis – Diffuse fibrosis with nodular regeneration o Acute HBV hepatitis
of hepatocytes accompanied by decrease in albumin,  HBsAg, IgM anti-HBc
increase PT, decreased cholesterol synthesis and o Chronic HBV hepatitis
insulin resistance.  HBsAg, IgG anti-HBc, IgG anti-HBs
 Hepatic Tumors – Cancer of the liver; increase ALP; o
normal bilirubin; LDH 2x normal; AFP increased; o Monitoring chronic HBV infection
increased GGT  HBs, HBeAg, anti-IgG anti-HBe, and
 Iron Storage Diseases ultrasensitive quantitative PCR
 Wilson’s Disease – Accumulation of copper in tissues
especially in the liver and brain; hepatocellular
degeneration
 Reye’s Syndrome – Fatty changes in the liver and
encephalopathy in its most severe form. Fatal; affects
mostly children.

HEPATITIS
a broad term that means inflammation of the liver
Etiology
 Viral
 Alcoholic
 Autoimmune
 Non-alcoholic steatohepatitis

VIRAL HEPATITIS
 Hepatitis A B C D E
 A is always acute, short term disease while hepatitis B
C D are most likely to become ongoing and chronic.
 E is usually acute but can be particularly dangerous in
pregnant women.
 A and E less common viruses can cause liver disease
o CMV
o Rubella
o EBV

Hepatitis A
- Picornavirus family
- RNA viruses
- Fecal-oral route
- Incubation period of 15-50 days with a mean time of
about a month
- Incubation period,
o HAV RNA (stool and in plasma)
o 18 days (detectable)