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Questions and Answers
What is the earliest sign of jaundice?
What is the earliest sign of jaundice?
Which condition is characterized by high levels of unconjugated bilirubin (UCB) overwhelming the liver's conjugating ability?
Which condition is characterized by high levels of unconjugated bilirubin (UCB) overwhelming the liver's conjugating ability?
In which type of jaundice does phototherapy serve as an effective treatment?
In which type of jaundice does phototherapy serve as an effective treatment?
What is the cause of kernicterus in physiologic jaundice of the newborn?
What is the cause of kernicterus in physiologic jaundice of the newborn?
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Which syndrome presents with a deficiency of the bilirubin canalicular transport protein?
Which syndrome presents with a deficiency of the bilirubin canalicular transport protein?
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What is a common clinical feature observed in Gilbert syndrome?
What is a common clinical feature observed in Gilbert syndrome?
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What distinguishes Crigler-Najjar syndrome from other forms of jaundice?
What distinguishes Crigler-Najjar syndrome from other forms of jaundice?
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Which of the following accurately describes a consequence of increased unconjugated bilirubin (UCB) in the blood?
Which of the following accurately describes a consequence of increased unconjugated bilirubin (UCB) in the blood?
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Study Notes
Jaundice
- Yellow discoloration of skin and sclera, caused by elevated serum bilirubin (usually > 2.5 mg/dL) This is the earliest sign
- Result of disturbances in bilirubin metabolism.
Normal Bilirubin Metabolism
- Breakdown of red blood cells (RBCs) by macrophages in the reticuloendothelial system.
- Conversion of protoporphyrin from heme to unconjugated bilirubin (UCB).
- Transport of UCB to the liver via albumin.
- Conjugation of bilirubin by uridine glucuronyl transferase (UGT) in hepatocytes to form conjugated bilirubin (CB).
- Transfer of CB to bile canaliculi and formation of bile, stored in the gallbladder.
- Release of bile into small intestine for digestion and absorption.
- Conversion of CB to urobilinogen by intestinal flora, then to stercobilin (for brown feces) and urobilin (for yellow urine).
Clinical features and Laboratory findings in Jaundice
- Extravascular hemolysis or Ineffective erythropoiesis: High UCB levels overwhelm the liver's ability to conjugate it resulting in dark urine due to increased urine urobilinogen . Risk of pigmented bilirubin gallstones.
- Physiological jaundice of the newborn: Transiently low UGT activity in newborns, resulting in increased UCB. Increased risk of kernicterus (brain damage) if untreated.
- Gilbert syndrome: Mildly low UGT activity; autosomal recessive, increased UCB.
- Crigler-Najjar syndrome: Absence of UGT; autosomal recessive, increased UCB, kernicterus usually fatal.
- Dubin-Johnson syndrome: Deficiency of bilirubin canalicular transport protein, autosomal recessive. Increased CB, decrease urine urobilinogen. Usually not clinically significant unless the liver is dark/brown.
- Rotor syndrome: Similar to Dubin-Johnson, but without liver discoloration. Increased bilirubin in blood.
- Biliary tract obstruction: Associated with gallstones, pancreatic carcinoma, cholangiocarcinoma, parasites, liver fluke. Increased CB, decreased urine urobilinogen, and increased alkaline phosphatase.
- Viral hepatitis: Inflammation disrupts hepatocytes; Increased CB, and UCB.
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Description
This quiz explores the causes and physiological processes associated with jaundice, focusing on bilirubin metabolism and its clinical implications. Understand the normal breakdown of red blood cells, the conversion of bilirubin, and the signs and symptoms of jaundice through clinical findings and laboratory results.
