Jaundice
The word jaundice comes from the French jaunisse, meaning yellow disease. This condition manifests as a yellowish or sometimes greenish pigmentation of the skin and sclera due to high bilirubin levels. Normal blood bilirubin stays below 1.0 mg/dl (17 μmol/L). Levels over 2, 3 mg/dl (34, 51 μmol/L) typically result in visible jaundice. Adults rarely develop this symptom, yet it appears in approximately 80% of newborns during their first week of life. The most common signs include itchiness, pale feces, and dark urine. Eye conjunctiva has a particularly high affinity for bilirubin deposition because of its high elastin content. Slight increases in serum bilirubin can be detected early by observing the yellowing of sclerae. In individuals with darker skin tones, jaundice may be less readily apparent on the skin. It is more reliably observed in areas such as the palms, soles, and oral mucosa.
When red blood cells complete their lifespan of about 120 days, they rupture as they pass through the reticuloendothelial system. Macrophages phagocytose free hemoglobin and split it into heme and globin. Two reactions then take place with the heme molecule. The first oxidation reaction is catalyzed by the microsomal enzyme heme oxygenase and results in biliverdin. The next step is the reduction of biliverdin to a yellow color tetrapyrrole pigment called bilirubin by cytosolic enzyme biliverdin reductase. This bilirubin is unconjugated, free, or indirect. Around 4 mg of bilirubin per kg of blood are produced each day. Roughly 20% comes from other heme sources including muscle myoglobin and cytochromes. Once unconjugated bilirubin arrives in the liver, liver enzyme UDP-glucuronyl transferase conjugates bilirubin plus glucuronic acid. Bilirubin that has been conjugated by the liver is water-soluble and excreted into the gallbladder. Bile enters the intestinal tract via bile where symbiotic bacteria convert it into urobilinogen.
Most people presenting with jaundice have various predictable patterns of liver panel abnormalities though significant variation does exist. The typical liver panel includes blood levels of enzymes found primarily from the liver such as aminotransferases ALT and AST. It also measures alkaline phosphatase ALP and protein levels specifically total protein and albumin. Other primary lab tests for liver function include gamma glutamyl transpeptidase GGT and prothrombin time PT. No single test can differentiate between various classifications of jaundice. A combination of liver function tests and other physical examination findings is essential to arrive at a diagnosis. Medical imaging such as ultrasound CT scan with contrast and HIDA scan are useful for detecting bile-duct blockage. Ultrasound and CT scans are routinely first line as they provide rapid results while remaining noninvasive and cost-effective. Liver biopsy may be indicated if labs or imaging do not determine the cause of jaundice.
Treatment of jaundice varies depending on the underlying cause. If a bile duct blockage is present surgery is typically required otherwise management is pharmacological. Medical management may involve treating infectious causes and stopping medication that could be contributing to the jaundice. The itchiness may be helped by draining the gallbladder ursodeoxycholic acid or opioid antagonists such as naltrexone. Jaundice in newborns may be treated with phototherapy or exchanged transfusion depending on age and prematurity when bilirubin is greater than 4, 21 mg/dl (68, 365 μmol/L). A bili light is often the tool used for early treatment which consists of exposing the baby to intensive phototherapy. Frequent and effective feedings are vital measures to decrease jaundice in infants since bilirubin count is lowered through excretion via bowel movements and urination.
Transient neonatal jaundice is one of the most common conditions occurring in newborns children under 28 days of age. More than 80 percent experience jaundice during their first week of life. Normal physiological neonatal jaundice is due to immaturity of liver enzymes involved in bilirubin metabolism. It also results from immature gut microbiota and increased breakdown of fetal hemoglobin HbF. Breast milk jaundice is caused by an increased concentration of β-glucuronidase in breast milk. This increases bilirubin deconjugation and reabsorption leading to persistence of physiologic jaundice with unconjugated hyperbilirubinemia. Onset of breast milk jaundice is within 2 weeks after birth and lasts for 4, 13 weeks. When bilirubin levels are very high brain damage known as kernicterus may occur leading to significant disability. Kernicterus is associated with increased unconjugated bilirubin which is not carried by albumin.
Jaundice in adults is rare while it is commonly associated with severity of disease in intensive care settings. Under the five year DISCOVERY programme in the UK annual incidence of jaundice was 0.74 per 1000 individuals over age 45. In the developed world the most common causes of jaundice are blockage of the bile duct or medication-induced. In the developing world the most common cause of jaundice is infectious such as viral hepatitis leptospirosis schistosomiasis or malaria. Risk factors associated with high serum bilirubin levels include male gender white ethnicities and active smoking. Mean serum total bilirubin levels in adults were found to be higher in men than women. Higher bilirubin levels in adults are found also in non-Hispanic white population and Mexican American population while lower in non-Hispanic black population. Bilirubin levels are higher in active smokers.
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Common questions
What is the origin of the word jaundice?
The word jaundice comes from the French jaunisse, meaning yellow disease. This condition manifests as a yellowish or sometimes greenish pigmentation of the skin and sclera due to high bilirubin levels.
When does jaundice typically appear in newborns?
Jaundice appears in approximately 80% of newborns during their first week of life. Transient neonatal jaundice occurs in children under 28 days of age with more than 80 percent experiencing it during that initial period.
How do doctors diagnose the cause of jaundice?
Medical imaging such as ultrasound CT scan with contrast and HIDA scan are useful for detecting bile-duct blockage. Ultrasound and CT scans are routinely first line as they provide rapid results while remaining noninvasive and cost-effective.
Why does jaundice occur in adults compared to newborns?
Adults rarely develop this symptom yet it appears in approximately 80% of newborns during their first week of life. Jaundice in adults is rare while it is commonly associated with severity of disease in intensive care settings.
What causes breast milk jaundice in infants?
Breast milk jaundice is caused by an increased concentration of β-glucuronidase in breast milk. This increases bilirubin deconjugation and reabsorption leading to persistence of physiologic jaundice with unconjugated hyperbilirubinemia.