Bilirubin & Jaundice275 BCHMiss Tahani Al-Shehri

Objective

•The aim of the experiment is to determine : ▫Total bilirubin ▫Direct bilirubin ▫Indirect bilirubin , Contents of human

serum .

Introduction •The liver responsible for many important

metabolic functions •> 100 lab tests associated with liver

function •Major hepatic functions •Protein synthesis •Regulation of carbohydrate metabolism •Regulation of lipoproteins •Detoxification of drugs and chemicals •Excretion of bile •Formation of bilirubin

Introduction

•Alkaline phosphatase•SGOT ( AST)•SGPT ( ALT)

▫These enzymes are released from dameged liver cells

Extravascular Pathway for RBC Destruction

(Liver, Bone marrow, & Spleen)

Hemoglobin

Globin

Amino acids

Amino acid pool

Heme Bilirubin

Fe2+

Excreted

Phagocytosis & Lysis

Recycled

DEGRADATION OF HEME TO BILIRUBIN

P450 cytochrome

·Bilirubin is the main pigment derived from heme catabolism

·75% is derived from RBCs

· In normal adults this results in a daily load of 200 mg of bilirubin

· Normal plasma concentrations are less then 1 mg/dL

· Hydrophobic – transported by albumin to the liver for further metabolism prior to its excretion

“unconjugated” bilirubin

Heme

Biliverdin

Unconjugated bilirubin

Reticuloendothelial system

Unconj.bilirubin/albumin complex

Systemic circulation

Hepatocytes

Unconj. bilirubin

Bilirubin diglucuronide

Small intestineLarge intestine

Bilirubin diglucuronideBilirubinUrobilinog

enStercobilins

Kidney

urine

HYPERBILIRUBINEMIA

-- elevated bilirubin in serum (above 3mg/dL) occur when there is imbalance between production and excretion

-- can be conjugated or unconjugated or both depending on the situation

-- elevated bilirubin can diffuse into tissues, making them appear yellow (jaundice)

HYPERBILIRUBINEMIA

Clinical Consequences:

-- Conjugated hyperbilirubinemia: benign

-- Unconjugated hyperbilirubinemia: benign at concentrations < 25 mg/dL (albumin capacity)

-- At concentrations >25 mg/dL, unconjugated bilirubin is free (uncomplexed) and can enter the brain.

bilirubin encephalopathy (kernicterus)

Causes of JAUNDICE

1) ( per-hepatic_ the pathology is occurring prior to the liver ) Ex. Hemolytic anemia

-- destruction of erythrocytes

2) ( hepatic _ the pathologyis located within the liver ) a)Hepatitis b) cirrhosis

-- conjugation and excretion of bilirubin

c) Neonatal “physiological jaundice”

-- immature hepatic system of the newborn:

uptake, conjugation, excretion of bilirubin

3) ( post-hepatic _ _ the pathology is occurring poster to the liver ) Bile duct obstruction

-- conjugated bilirubin not delivered to intestine;

it backs up, spills over into the blood

principle•Direct bilirubin water soluble •Bilirubin + Diazo reagent

Red –blue color

* Only direct bilirubin react .

principle

•Direct bilirubin water soluble •Bilirubin + Diazo reagent + caffeine

Red –blue color

Direct + indirect bilirubin react .

•Total bilirubin = Conjugated + Un conjugated Bilirubin.