Jaundice Flashcards
What is jaundice and how is it clinically identified in adults?
Jaundice is characterized by yellow discoloration of the skin and sclera. In adults, examining the sclera is the easiest way to detect jaundice.
Why is detecting jaundice in newborns more challenging?
Detecting jaundice in newborns is more challenging because of the difficulty in seeing the sclera. Therefore, it is easier to detect jaundice in the skin of newborns.
At what bilirubin level does clinical jaundice become evident?
Clinical jaundice becomes evident when bilirubin levels are about 75 µmol.
How does the difficulty of detecting jaundice increase in dark-skinned infants?
Detecting jaundice in dark-skinned infants is more difficult due to the skin pigmentation.
What technique can be used to detect jaundice in newborns with difficulty in seeing the sclera?
Gently pressing on the tip of the infant’s nose and then examining the color of the skin immediately upon releasing the pressure can help detect jaundice in newborns.
How common is jaundice in newborns?
Jaundice is extremely common in newborns, with 60% of term infants and 80% of pre-term infants exhibiting visible clinical jaundice in the first week of life. Additionally, up to 10% of breastfed infants may show jaundice at 1 month of age.
Why is it important to understand the underlying physiology of jaundice in newborns?
Understanding the underlying physiology of jaundice in newborns is crucial for recognizing when jaundice may be pathological and knowing how to investigate and treat it.
What should healthcare providers be able to recognize regarding jaundice in newborns?
Healthcare providers should be able to recognize when jaundice in newborns may be pathological, as opposed to physiological, and require further investigation and treatment.
What are some important aspects of investigating jaundice in newborns?
Investigating jaundice in newborns involves understanding the underlying cause, which may include assessing bilirubin levels, evaluating liver function, and considering any underlying conditions or risk factors.
How should jaundice in newborns be treated?
Treatment for jaundice in newborns may vary depending on the underlying cause and severity. Options may include phototherapy, exchange transfusion, addressing any underlying conditions, and ensuring adequate feeding and hydration.
Where are red blood cells removed from circulation, and what happens to them afterward?
Red blood cells are primarily removed from circulation in the reticulo-endothelial system, mainly in the spleen. After removal, hemoglobin from these red blood cells is broken down into heme and globin.
What happens to globin after the breakdown of hemoglobin?
Globin, a component of hemoglobin, is metabolized into amino acids after the breakdown of hemoglobin.
How is heme metabolized after the breakdown of hemoglobin?
Heme, another component of hemoglobin, is metabolized into biliverdin, which is then converted into bilirubin.
Besides the breakdown of hemoglobin, when else is bilirubin formed?
Bilirubin is also formed during the breakdown of myoglobin and cytochromes, not just hemoglobin.
What is the primary binding protein for unconjugated bilirubin in plasma?
Unconjugated bilirubin in plasma is primarily bound to albumin
How is unconjugated bilirubin primarily removed in the fetus?
In the fetus, most unconjugated bilirubin is rapidly removed by the placenta. However, about 10% is still conjugated in the fetal liver and excreted into the gut.
What happens to unconjugated bilirubin in the fetal gut?
In the fetal gut, unconjugated bilirubin is deconjugated by the enzyme beta glucuronidase and then reabsorbed via the enterohepatic circulation.
How is fetal bilirubin maintained to facilitate its excretion across the placenta?
Most fetal bilirubin is maintained in the unconjugated state to facilitate its excretion across the placenta.
What enzyme is responsible for conjugating bilirubin in the newborn infant?
In the newborn infant, bilirubin is conjugated with glucuronic acid by the enzyme glucuronyl transferase.
How does the handling of bilirubin change after separation from the placenta in newborn infants?
After separation from the placenta, progressively more bilirubin is taken up by the liver and conjugated with glucuronic acid by the enzyme glucuronyl transferase in newborn infants.
What is the characteristic of conjugated bilirubin regarding its solubility and toxicity?
Conjugated bilirubin is water-soluble and is not toxic to brain tissue.
How is conjugated bilirubin excreted from the body?
Conjugated bilirubin is excreted through the bile duct system into the duodenum.
What happens to most of the conjugated bilirubin in the gut?
Most of the conjugated bilirubin in the gut is broken down to stercobilin by bacteria, to be excreted in the stool.
What is the fate of some of the conjugated bilirubin in the gut?
Some of the conjugated bilirubin in the gut is de-conjugated (back into unconjugated bilirubin) and reabsorbed.
How long does the enterohepatic circulation of bilirubin typically remain after delivery?
The enterohepatic circulation of bilirubin typically remains for a few weeks after delivery.
What role does the intestinal enzyme beta glucuronidase play in neonatal jaundice?
Beta glucuronidase, present in breast milk, is responsible for the enterohepatic circulation of bilirubin, contributing to neonatal jaundice, which is more common in breastfed infants.
Why is neonatal jaundice more common in breastfed infants compared to formula-fed infants?
Neonatal jaundice is more common in breastfed infants because breast milk contains the intestinal enzyme beta glucuronidase, which contributes to the enterohepatic circulation of bilirubin.
What happens if there is obstruction to the biliary tree in newborns?
If there is obstruction to the biliary tree, conjugated bilirubin enters the plasma and may be excreted in the urine.
What is the role of bilirubin as an oxygen free radical scavenger?
Bilirubin acts as an oxygen free radical scavenger, helping to neutralize and eliminate free radicals in the body.
How does mild jaundice potentially reduce the risk of damage during labor?
Mild jaundice may reduce the risk of damage by free radicals generated during labor, as bilirubin acts as an oxygen free radical scavenger.
What is the prevalence of increased unconjugated bilirubin levels in newborn infants?
All normal newborn infants have increased amounts of unconjugated bilirubin in their blood, and more than half develop visible jaundice
When does physiological jaundice typically present in newborn infants?
Physiological jaundice typically presents on the second or third day after birth.
When does physiological jaundice usually peak and disappear in newborns?
Physiological jaundice usually peaks by day 3 or 4 and disappears within 7 days in most infants.
What is the typical range of total serum bilirubin (TSB) in formula-fed infants?
The total serum bilirubin (TSB) usually does not exceed 200 µmol/l in formula-fed infants.
What is the potential range of total serum bilirubin (TSB) in healthy breastfed infants?
In some healthy breastfed infants, the total serum bilirubin (TSB) might reach as high as 275 µmol/l.
How is the diagnosis of physiological jaundice typically made in infants?
The diagnosis of physiological jaundice in infants is made by excluding pathological causes of jaundice in infants who are active, feed well, and show no sign of illness.
What are some key characteristics of physiological jaundice in terms of onset and duration?
Physiological jaundice never appears within the first 24 hours of life and seldom lasts beyond 7 days.
What are the recommended interventions for physiological jaundice in infants?
Physiological jaundice typically does not require treatment other than reassuring the mother, encouraging frequent feeds, and monitoring the infant for abnormal signs.
What are some signs that distinguish physiological jaundice from pathological jaundice in infants?
Signs such as activity level, feeding behavior, and absence of other illness symptoms help distinguish physiological jaundice from pathological jaundice in infants.
How long should physiological jaundice typically be monitored before considering further intervention?
Physiological jaundice should be monitored until it resolves within the typical timeframe, usually within 7 days, before considering further intervention.
Physiological jaundice is due to a combination of
- The high haematocrit and shorter red cell survival time, which results in a high
bilirubin production. - Slow hepatic conjugation (immature glucuronyl transferase enzyme).
- The enterohepatic circulation of bilirubin (beta glucuronidase in the intestinal
brush border).
Why are preterm infants especially likely to develop clinical jaundice?
Preterm infants are especially likely to develop clinical jaundice because they have an immature liver with a limited ability to conjugate bilirubin in the first weeks of life.
What is the reason behind some term infants developing ‘idiopathic hyperbilirubinemia’?
Some term infants develop ‘idiopathic hyperbilirubinemia’ because they also have a slow rate of bilirubin conjugation, leading to elevated bilirubin levels.
What is ‘breast milk jaundice’ and who is at risk of developing it?
‘Breast milk jaundice’ is a condition where breastfed infants develop prolonged unconjugated hyperbilirubinemia with jaundice that lasts several weeks. Breastfed infants are at risk of developing this condition.
What may be the underlying cause of ‘breast milk jaundice’?
‘Breast milk jaundice’ may be the result of increased enterohepatic circulation of bilirubin, likely due to the presence of beta glucuronidase in breast milk.
How does the immature liver of preterm infants contribute to clinical jaundice?
The immature liver of preterm infants has a limited ability to conjugate bilirubin in the first weeks of life, leading to an increased risk of clinical jaundice.
What is the difference in toxicity between conjugated and unconjugated bilirubin?
Conjugated bilirubin is not toxic, whereas free unconjugated bilirubin is toxic.
How does unconjugated bilirubin bound to albumin behave differently from free unconjugated bilirubin
Unconjugated bilirubin bound to albumin crosses the blood-brain barrier less readily than free unconjugated bilirubin.