ASSESSMENT OF LIVER FUNCTION

Storage

Synthetic

Detoxification

Secretory and excretory

FUNCTIONS OF THE LIVER ?

• major sites of glycogenesis

Storage

FUNCTIONS OF THE LIVER:

• glycogen, fat-soluble vitamins A,D,E,K

Synthetic

FUNCTIONS OF THE LIVER:

• lipids, carbohydrates, proteins Total Protein, Albumin, Globulin (except gamma globulin)

Detoxification

FUNCTIONS OF THE LIVER:

• drugs, poisons, and metabolic products Ammonia, Unconjugated Bilirubin

Secretory and excretory

FUNCTIONS OF THE LIVER:

• conjugated bilirubin

Plasma Cells

Gamma globulins are produced by ________ not the liver!

Hepatitis

Cirrhosis

Fulminant hepatic failure

Examples of Hepatocellular Disorders ?

• HCF

Biliary obstruction

Space-occupying lesion

Passive congestion

Examples of Hepatobilliary Disorders ?

• BSP

AST , ALT, LD

What are the Hepatocellular Markers?

ALT

Most specific Hepatocellular Marker?

ALP

What is the Hepatobilliary Marker?

TP, Albumin

What are the Marker for Synthetic Function?

Bilirubin

What are the Marker for Secretory / Excretory Function?

Bilirubin, Ammonia

What are the Marker for Detoxification Function?

Hepatitis

Differential diagnosis of liver disorders

AST, ALT, LD, ALP, BILI

• High

TP, ALB, AMMONIA

• Normal

Cirrhosis

Differential diagnosis of liver disorders

AST, ALT, LD, ALP

• Normal

TP, ALB

• Low

BILI, AMMONIA

• High

Fulminant hepatic failure

Differential diagnosis of liver disorders

AST, ALT, LD, ALP

• Very High (AST only)

• High

TP, ALB

• Low

BILI, AMMONIA

• High

Biliary obstruction

Differential diagnosis of liver disorders

AST, ALT, LD, TP, ALB, AMMONIA

• Normal

ALP, BILI

• High

Space-occupying lesion

Differential diagnosis of liver disorders

AST, ALT, LD, BILI

• Normal - High (for AST, ALT, Bili)

TP, ALB, AMMONIA

• Normal

LD, ALP

• High

Passive congestion

Differential diagnosis of liver disorders

AST, ALT, LD, ALP, BILI

• Slightly High

ALP, BILI

• Normal to Slightly High

TP, ALB, AMMONIA

• Normal

Panhepatic cirrhosis

destruction of more than 80% of liver tissue, with no regeneration.

Fulminant hepatic failure

results from a variety of causes

• e.g. Reye syndrome, hepatitis, cirrhosis

B1

FORMS OF BILIRUBIN IN PLASMA:

Origin: Pre-Hepatic / Hemolytic

Structure: Unconjugated

Solubility in H2O: Insoluble

Polarity: Non-polar

Reaction w Diazo Rgt: Indirect (requires accelerator)

Excreted in urine: No

Affinity for CNS: Yes, High (may cause kernicterus)

• among newborns w/ unconjugated hyperbilirubinemia

also called “Alpha”

B2

FORMS OF BILIRUBIN IN PLASMA:

Origin: Post-Hepatic / Obstructive / Reguvgitation

Structure: Conjugated

Solubility in H2O: Soluble

Polarity: Polar

Reaction w Diazo Rgt: Direct

Excreted in urine: Yes but only if it’s free or unbound

Affinity for CNS: No or Low

Has three types:

• “Beta” (monoconjugated bilirubin)

• “Gamma” (diconjugated bilirubin)

• “Delta” (B2 that is bounded to albumin)

Delta Bilirubin

Conjugated bilirubin covalently bound to Albumin

Long half-life 17 days (2 and a half weeks)

Seen in cases of Biliary obstruction (cholelithiasis)

Reaction with diazo reagent Direct

Separated from other fractions by HPLC

Unconjugated hyperbilirubinemia

Physiological Classification of Jaundice:

• ↑ B1 due to ↑ production, ↓ delivery and uptake, or ↓ conjugation

Conjugated hyperbilirubinemia

Physiological Classification of Jaundice:

• ↑ B2 due to intra- or extrahepatic cholestasis

Mixed hyperbilirubinemia

Physiological Classification of Jaundice:

• ↑ B1 and B2 due to a combination of defects

Pre-hepatic/ hemolytic

Types of Jaundice according to origin:

Serum bilirubin: ↑ B1

Urine bilirubin: Negative

Urine urobilinogen: 3+ (due to ineffective hepatic uptake)

Hepatic

Types of Jaundice according to origin:

Serum bilirubin: ↑ B1, B2 or Both

Urine bilirubin: Negative / Positive

Urine urobilinogen: 2+ (due to ineffective hepatic uptake)

Post-hepatic/ obstructive

Types of Jaundice according to origin:

Serum bilirubin: ↑ B2

Urine bilirubin: 3+ (High)

Urine urobilinogen: Normal in Rgt Strip Test ; (-) / Low in Quantitative method

Hemolytic disease

What Disorder?

Type: Unconjugated Hyperbilirubinemia (Pre-Hepatic)

B1: High

B2: Normal

Defect: ↑ RBC destruction = ↑ Bilirubin production

Gilbert syndrome

Lucey-Driscoll syndrome

Physiologic jaundice of the newborn

Crigler-Najjar syndrome

What Disorder?

Type: Unconjugated Hyperbilirubinemia (Hepatic)

B1: High

B2: Normal

Defect:

• Transport defect coupled with UDPGT deficiency

• Circulating inhibitor of bilirubin conjugation

• Transient UDPGT deficiencyUD

• Total or partial UDPGT deficiency

  • Homozygous = Total

  • Heterozygous = Partial

Gilbert’s Syndrome

What Metabolism error?

• ↑ B1

• Defect in transport of B1 to hepatocytes

Crigler-Najjar syndrome

What Metabolism error?

• ↑ B1

• Defect in UDPGT

Viral hepatitis/ Cirrhosis Hepatic carcinoma

What Disorder?

Type: Mixed Hyperbilirubinemia (Hepatic)

B1: High

B2: High

Defect: ↓ Conjugation; Bile flow interference

• High B1 ; High B2

Dubin-Johnson syndrome

Rotor syndrome

What Disorder?

Type: Conjugated or Mixed Hyperbilirubinemia (Hepatic)

B1: Normal to Increase

B2: High

Defect: Secretory defect ; defect in excretion of B2 by hepatocytes

• cholestasis

• dark pigmentation of hepatocytes

Biliary obstruction

What Disorder?

Type: Conjugated Hyperbilirubinemia (Pre-Hepatic)

B1: Normal

B2: High

Defect: Extrahepatic cholestasis

• Caused by: Cholelithiasis, tumors, structure

• Avoid exposure to light = Photo-oxidation of bilirubin

• Hemolysis = assay inference (falsely decreased)

BILIRUBIN DETERMINATION:

• Specimen Considerations:

Colorimetric-Spectrophotometric

METHODS:

• based on the Van Den Borgh reaction (diazotization with incorporated accelerator/solubilizer)

Evelyn-Malloy

Reagents: Diazo reagents

• Diazo A = 0.1% sulfanilic acid in HCl

• Diazo B = 0.5% sodium nitrite

• Diazo blank = 1.5% HCl

Accelerator: Methanol

pH of the reaction: Acid

Color reaction: Red-Purple

Absorbance maximum: 560 nm

Jendrassik-Grof

Reagents: Diazo reagents

• Sodium acetate

• Ascorbic acid - Stopping reagent

• Alkaline tartrate (Fehling’s reagent) - alkanizes the medium

Accelerator: Caffeine

pH of the reaction: Alkaline

Color reaction: Blue

Absorbance maximum: 600 nm

Ascorbic Acid

Stopping Reagent for Jendrassik Grof

Total bilirubin

Bilirubin + Diazo + Accelerator → Azodipyrroles (all fractions)

• w/o accelerator B2, delta will be detected

Direct bilirubin

Bilirubin + Diazo → Azodipyrroles (B2 and delta only)

Indirect bilirubin

Calculated → TB – DB

Direct spectrophotometry (Bilirubinometry)

• based on the absorption of light by bilirubin at 450 nm; correction for oxyhemoglobin is achieved by measuring absorbance at two wavelengths

• appropriate only for neonates; not done on adult serum due to the presence of carotenoid pigments

Enzymatic

involves oxidation of bilirubin to biliverdin by bilirubin oxidase at different pH levels followed by further oxidation to a colorless product and measurement of the decrease in absorbance

0.2-0.8 mg/dL

Reference Values for B1:

0-0.2 mg/dL

Reference Values for B2:

0.2-1.0 mg/dL

Reference Values for Total Bilirubin: