Physiological Jaundice

Question 1

Describe what bilirubin is and how it is broken down and excreted

Answer 1

• bilirubin is a breakdown product of haemoglobin from red blood cells
• ageing, immature or malformed red blood cells are removed from the circulation and broken down in the reticuloendothelial system (liver, spleen and macrophages)
• haemoglobin in the red blood cells are broken down into byproducts of haem, globin and iron
  - -> haem is converted to bilverdin and then unconjugated bilirubin
  - -> globin is broken down into amino acids which are used in the body to make new proteins
  - -> iron is stored in the body or used for new red blood cells
• the unconjugated bilirubin is then transported to the liver bound to serum albumin
  - -> once in the liver unconjugated bilirubin is detached from albumin, combined with glucose and glucuronic acid
  - -> this causes conjugation to occur using the enzyme uridine diphosphoglucuronyl transferase (UDP-GT)
• the conjugated bilirubin is now water-soluble and available for excretion
• it is excreted via the biliary system into the small intestine where normal bacteria change the conjugated bilirubin into urobilinogen
• this is then oxidised into orange-coloured urobilin
• most is excreted in the faeces with a small amount in urine

Question 2

What causes physiological jaundice?

Answer 2

• all newborn babies have a rise in unconjugated bilirubin during the first few days after birth which occurs for several reasons
  - -> the turnover of haemoglobin is high in the fetus and newborn but before birth the bilirubin from the fetus is removed via the placenta
  - -> at birth as the more efficient lungs increase oxygen levels, there is haemolysis of excessive RBC’s that are now not needed
  - -> at birth the newborn liver enzyme systems may be immature and not as effective
• as a result of these factors there is a rise in serum unconjugated bilirubin in babies during the first few days after birth

Question 3

Describe the pattern that babies showing signs of physiological jaundice will follow

Answer 3

• most babies will look yellow by day 3-4
• as unconjugated bilirubin levels rise the serum albumin becomes saturated and then any excesses spills over into the blood plasma
• unconjugated bilirubin is fat-soluble and so it will deposit in subcutaneous fat which makes the skin appear yellow

Question 4

Describe the role of the midwife when assessing physiological jaundice

Answer 4

• act on any deviations from the norm
• any baby who is visibly jaundiced should have SBR level checked (NICE 2010)
• take a feeding history and check weight
• identify if there are any risk factors for bilirubin encephalopathy or pathological jaundice