Introduction:
Bilirubin is a yellowish pigment that is produced when red blood cells break down. It is processed by the liver and excreted in the bile. Bilirubin exists in two forms in the blood: unconjugated (or indirect) bilirubin and conjugated (or direct) bilirubin. Unconjugated bilirubin is the form of bilirubin that is not yet processed by the liver. It is a fat-soluble substance and cannot be excreted in the urine. Instead, it binds to albumin and is transported to the liver, where it is conjugated (modified) by the addition of a sugar molecule. The conjugated bilirubin is then excreted in the bile and eliminated from the body in the stool. Elevated levels of unconjugated bilirubin in the blood can lead to a condition called jaundice (the skin and whites of the eyes become yellow). This can occur when the liver is unable to process the bilirubin efficiently, such as in cases of liver disease, hemolytic anemia, or genetic disorders affecting bilirubin metabolism.
What Is the Incidence of Unconjugated Bilirubinemia?
The incidence of unconjugated bilirubinemia mainly depends on the condition's underlying cause. Hemolytic anemia, one of the most common causes of unconjugated bilirubinemia, can affect people of any age but is more common in infants and young children. Gilbert's Syndrome, a genetic disorder affecting the liver's ability to process bilirubin, is estimated to affect around 4 to 10 % of the population. Crigler-Najjar syndrome, a rare genetic disorder that prevents the liver from adequately conjugating bilirubin, is extremely rare, with an estimated incidence of 1 in 1,000,000. In cases where unconjugated bilirubinemia is caused by liver disease or dysfunction, the condition's incidence can vary depending on the underlying cause of the liver disorder.
The exact incidence of unconjugated bilirubinemia may be challenging to determine as not all cases are diagnosed or reported.
What Are the Causes of Unconjugated Bilirubinemia?
There are several causes of unconjugated bilirubinemia. These are explained following:
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Hemolytic Anemia - Hemolytic anemia is an abnormal condition of red blood cells. The fast breakdown of red blood cells characterizes it. As a result, excessive bilirubin will build up.
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Gilbert's Syndrome - It is a rare genetic disorder. Gilbert's syndrome affects the liver's ability to process bilirubin, leading to a build-up of elevated bilirubin levels in the blood that result in unconjugated bilirubinemia.
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Crigler-Najjar Syndrome - Crigler-Najjar syndrome is also a rare genetic disorder. It is characterized by preventing the liver from adequately conjugating bilirubin, leading to high levels of unconjugated bilirubin in the blood. It can cause serious complications if left untreated.
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Liver Disease or Dysfunction - Unconjugated bilirubinemia also occurs due to several liver diseases or dysfunctions. These include conditions such as viral infections, cirrhosis of the liver, or other liver disorders. This disorder affects the ability of the liver to process and excrete bilirubin, leading to elevated bilirubin levels in the blood.
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Toxins and Medications - It is observed that certain toxins and medications can cause unconjugated bilirubinemia. This substance can damage the liver or red blood cells, producing excess bilirubin in the blood.
What Are the Symptoms of Unconjugated Bilirubinemia?
Symptoms of unconjugated bilirubinemia include the following:
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Fatigue and Weakness - Elevated bilirubin levels in the blood result in fatigue and weakness. These symptoms occur due to the body trying to process and excrete the excess bilirubin out of the body.
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Abdominal Pain - Patients with unconjugated bilirubinemia may experience abdominal pain, which can signify liver dysfunction or infection.
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Jaundice - Jaundice is the most common symptom of unconjugated bilirubinemia. In jaundice, the skin and white part of the eye become yellow due to the increased bilirubin level in the blood.
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Headaches - Excess bilirubin levels can cause headaches in patients because the excess bilirubin in the blood applies pressure on the blood vessels in the brain.
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Dark Urine - High bilirubin levels result in dark urine due to the excretion of bilirubin in the urine.
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Confusion and Drowsiness - Bilirubin affects the brain and causes confusion and drowsiness. These symptoms are hazardous in older adults or those with pre-existing neurological conditions (brain problems).
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Itching - High levels of bilirubin in the blood can cause itching as it can cause the accumulation of bilirubin in the skin.
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Other Symptoms - Unconjugated bilirubinemia can cause complications like brain damage or hearing loss.
What Is the Diagnosis of Unconjugated Bilirubinemia?
Diagnosis of unconjugated bilirubinemia includes the following:
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Blood Test - A blood test measures bilirubin levels in the blood. This will help determine if there is an excess of unconjugated bilirubin present.
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Complete Blood Count (CBC) - It measures the number and types of cells in the blood. It determines if an underlying condition, such as hemolytic anemia, can cause unconjugated bilirubinemia.
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Liver Function Tests - These tests evaluate the function of the liver and can help identify any underlying liver disease or dysfunction.
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Genetic Testing - Genetic testing is done in cases where a genetic disorder such as Gilbert's syndrome or Crigler-Najjar's syndrome is suspected of causing unconjugated bilirubinemia.
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Urine Test - A urine test checks for bilirubin and other byproducts of bilirubin metabolism. These can indicate liver dysfunction or other underlying conditions.
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Coombs Test - In the case of hemolytic anemia, the Coombs test checks for the presence of antibodies responsible for destroying red blood cells.
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Reticulocyte Count - This test checks the number of immature red blood cells in the blood. It indicates increased destruction of red blood cells.
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Other Tests - Additional tests may be performed based on the individual's symptoms and medical histories, such as imaging tests or liver biopsies.
What Is the Treatment of Unconjugated Bilirubinemia?
Treatment for unconjugated bilirubinemia depends upon its cause for it. The treatment options are as follows:
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Hemolytic Anemia - Treatment is based on the underlying cause of the anemia. Treatment options involve such as managing a blood disorder or infection. In addition, medications such as corticosteroids or blood transfusions may increase the number of red blood cells in the body.
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Gilbert's Syndrome - In these cases, treatment may not be necessary, as it does not cause serious symptoms. However, in some cases, medications such as ursodeoxycholic acid may help the liver process bilirubin more efficiently.
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Crigler-Najjar Syndrome - Treatment involves phototherapy or exchange transfusion (exchange of the blood). Phototherapy uses light to break down bilirubin in the skin. Exchange transfusion is a treatment in which a baby's blood is replaced with donated blood to remove bilirubin.
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Liver Disease or Dysfunction - Treatment may involve treating a viral infection or managing liver cirrhosis. Medications are given to help the liver function more efficiently and reduce the build-up of bilirubin in the blood.
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Toxins and Medications - Discontinue the medication or toxin causing the unconjugated bilirubinemia and address any underlying conditions caused by the toxin or medication.
Conclusion:
Elevated levels of unconjugated bilirubin in the blood characterize unconjugated bilirubinemia. It can be caused by several conditions, including hemolytic anemia, Gilbert's syndrome, and Crigler-Najjar syndrome. Symptoms vary from mild to severe; treatment and prevention depend on the underlying cause. Therefore, if a person suspects unconjugated bilirubinemia, it is essential to consult a healthcare provider for proper diagnosis and treatment
