Jaundice occurs when the serum bilirubin level rises above 3 mg/dl. Clinical signs include yellowing of the sclera and skin. Symptoms vary with the underlying cause and may include loss of appetite, arthralgia, itching, rashes, nausea and vomiting, myalgia, and fever.
Unconjugated (indirect) bilirubin is insoluble in water but soluble in lipids, so it can cross lipid-rich cell membranes. In serum, it’s transported bound to albumin. In the liver, bilirubin is conjugated by the enzyme glucuronyl transferase. Conjugated (direct) bilirubin is water soluble.
Conjugated hyperbilirubinemia results from disorders that primarily affect the liver (e.g., hepatitis) or from extrahepatic cholestasis (e.g., biliary strictures or masses obstructing the common bile duct).
Unconjugated hyperbilirubinemia results from either:
Imaging studies help identify the underlying cause. Ultrasound and CT scans help evaluate parenchymal liver and gallbladder disorders, while ERCP and MRCP are used to detect intrahepatic and extrahepatic biliary tree lesions. Endoscopic ultrasound helps visualize the type of lesion obstructing the biliary tree. A liver biopsy can help confirm hepatic parenchymal disorders. Autoimmune antibodies are detected in serological studies of autoimmune hepatitis.
Elevated AST (SGOT) and ALT (SGPT) suggest liver dysfunction, but they can be normal or even low when there is loss of liver parenchymal tissue in cirrhosis. AST and ALT can reach >10,000 U/L in hepatic injury from drugs like acetaminophen or from ischemia.
Hepatic causes of elevated alkaline phosphatase include biliary obstruction and parenchymal liver disease. Gamma glutamyl transferase is elevated in biliary obstruction and alcoholic liver disease.
In alcoholic hepatitis, the ratio AST>ALT, while in infectious hepatitis ALT>AST
| Type of jaundice | Total bilirubin | Direct bilirubin | Urine bilirubin |
| Unconjugated | Raised | Normal | Absent |
| Conjugated | Raised | Raised | Present |
Dubin Johnson syndrome is a hereditary conjugated hyperbilirubinemia seen in Iranian and Moroccan Jews living in Israel and in the Japanese population. It is AR.
Dubin Johnson syndrome is caused by mutations in the ABCC2 gene, which codes for the protein MRP2 (multidrug resistance associated protein 2). This mutation decreases transport of bilirubin and some other molecules from hepatocytes into the bile canaliculi.
It presents with jaundice, fatigue, abdominal pain, nausea, vomiting, hepatomegaly, and conjugated hyperbilirubinemia. The liver appears black due to accumulation of epinephrine metabolites. In asymptomatic women with Dubin Johnson syndrome, pregnancy or OC pill use may precipitate symptoms.
Patients generally do well even without specific treatment. Medications with hepatotoxicity should be taken under careful medical supervision.
Rotor syndrome is an AR inherited cause of hyperbilirubinemia caused by mutations in the SLCO1B1 and SLCO1B3 genes, which code for organic anion transporting polypeptide 1B1 (OATP1B1) and organic anion transporting polypeptide 1B3 (OATP1B3), respectively. This causes a defect in transporting bilirubin from the blood into hepatocytes.
It presents with mild, recurrent jaundice. Both conjugated (++) and unconjugated bilirubin (+) levels are elevated. Rotor syndrome is considered a benign disorder and does not require treatment.
Gilbert syndrome is a common inherited AR or AD disorder that causes unconjugated hyperbilirubinemia. It is caused by mutations in the UGT1A1 gene, which codes for the enzyme bilirubin uridine diphosphate glucuronyl transferase (bilirubin UGT) that converts unconjugated bilirubin to conjugated bilirubin. Patients have reduced enzyme activity. Many mutations occur in the promoter region of the gene.
Jaundice may not always be present, but hyperbilirubinemia can be detected on serological testing under certain conditions such as dehydration, vigorous exercise, fasting, illness, alcohol, or menstruation. Most people are asymptomatic, and no specific treatment is needed. Some patients may develop diarrhea after administration of irinotecan.
Criggler Najjar syndrome is a rare AR inherited cause of unconjugated hyperbilirubinemia caused by mutations in the UGT1A1 gene that codes for bilirubin uridine diphosphate glucuronosyl transferase (bilirubin-UGT) (the same gene as Gilbert syndrome). This impairs conjugation (glucuronidation) of bilirubin to form conjugated bilirubin.
There are two types of Criggler-Najjar syndrome: types 1 and 2. Type 1 is more severe, with a total absence of enzyme function, while type 2 has about 20% enzyme function.
It presents with jaundice, kernicterus (more common in type 1), and unconjugated hyperbilirubinemia. Patients may develop bilirubin encephalopathy during illness, prolonged fasting, or under anesthesia.
Phototherapy is used to correct acute episodes of hyperbilirubinemia. Type 2 may also respond to phenobarbital, while type 1 does not. Exposure to sunlight helps reduce mild elevations in bilirubin levels. Plasmapheresis can remove unconjugated bilirubin and can be used in addition to phototherapy. Liver transplantation is the only definitive treatment for type 1 disease.
Autoimmune hepatitis (AIH) is inflammation of the liver that can progress to cirrhosis. It’s seen in autoimmune disorders like SLE and Hashimoto’s thyroiditis, and it is more common in women.
It presents with fatigue, nausea, loss of appetite, jaundice, pruritus, arthralgia, and (in advanced cases) signs of cirrhosis.
Laboratory findings include elevated AST and ALT, IgG, gamma globulins, ANA, anti-smooth muscle antibodies, and anti-LKM1 (liver-kidney microsomal) antibodies. HLA DR3 and DR4 may be positive. Liver biopsy shows typical features of inflammation and, in severe cases, cirrhosis.
It responds to corticosteroids, azathioprine, mycophenolate mofetil, cyclosporine, or tacrolimus. Maintenance therapy is with prednisone or azathioprine. A liver transplant may be needed.
Non-alcoholic fatty liver disease (NAFLD) is seen in middle-aged, overweight, or obese individuals with metabolic syndrome and insulin resistance, prediabetes, diabetes, or elevated cholesterol and triglycerides. Some children may be affected. It is characterized by lipid accumulation in hepatocytes and is not caused by alcohol. In fatty liver, the liver contains more than 5-10% fat.
Variations in the PNPLA3 gene that codes for adiponutrin (a lipase), leading to increased lipid production and decreased lipolysis, have been implicated. Inflammation involves activation and recruitment of inflammatory cells and activation of stellate cells that secrete collagen, resulting in fibrosis. Increased production of reactive oxygen species occurs due to uncoupling of oxidative phosphorylation, causing more hepatocyte damage. Endotoxins may activate Kupffer cells via Toll Like Receptors TLR2 and 4, leading to increased synthesis of TNF alpha and IL1. Increased lipolysis of adipose tissue releases more free fatty acids, which are converted and stored in the liver as triglycerides.
Most patients are asymptomatic. Some may present with fatigue, abdominal pain, mild hepatomegaly, and signs of cirrhosis in severe cases. Once inflammation develops, 30% cases progress to cirrhosis. There is also increased risk of hepatocellular carcinoma.
Biopsy findings include typical changes of fatty liver, ballooning degeneration, and perivenular and perisinusoidal fibrosis with inflammatory infiltrate. Mallory bodies may be seen. Classically, lipid in NAFLD accumulates around the central vein (zone 3) in adults, but as the disease progresses, it may show a panlobular distribution involving all zones.
Laboratory findings include elevated AST and ALT. Management is by weight reduction, healthy eating, increasing physical activity, and avoiding hepatotoxic agents like alcohol and certain medications. Treating insulin resistance with metformin, rosiglitazone and pioglitazone helps. Antioxidants like vitamin E, selenium and betaine may also help.
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