Neonatal jaundice medical therapy

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Medical Therapy

Infants with neonatal jaundice are often treated with bili lights, exposing them to high levels of colored light to break down the bilirubin. This works due to a photo oxidation process occurring on the bilirubin in the subcutaneous tissues of the neonate. Light energy creates isomerization of the bilirubin and consequently transformation into compounds that the new born can excrete via urine and stools. Blue light is typically used for this purpose.

The bilirubin levels for initiative of phototherapy varies depends on the age and health status of the newborn. However any newborn with a total serum bilirubin greater than 359 umol/l ( 21 mg/dL ) should receive phototherapy.

Phototherapy

The use of phototherapy was first discovered, accidentally, at Rochford Hospital in Essex, England. The ward sister (Charge Nurse) of the premature baby unit, firmly believed that the infants under her care benefited from fresh air and sunlight in the courtyard. Although this led to the first noticing of jaundice being improved with sunlight, further studies only progressed when a vial of blood sent for bilirubin measurement sat on a windowsill in the lab for several hours. The results indicated a much lower level of bilirubin than expected based on the patient's visible jaundice. Further investigation lead to the determination that blue light, wavelength of 420-448 nm, oxidized the bilirubin to biliverdin, a soluble product that does not contribute to kernicterus. Although some pediatricians began using phototherapy in the United Kingdom following Dr. Cremer's publishing the above facts in the Lancet in 1958, most hospitals only began to regularly use phototherapy ten years later when an American group independently made the same discovery.

Infants with neonatal jaundice are treated with colored light called phototherapy. Physicians randomly assigned 66 infants 35 weeks of gestation to receive phototherapy. After 15±5 the levels of bilirubin, a yellowish bile pigment that in excessive amounts causes jaundice, were decreased down to 0.27±0.25 mg/dl/h in the blue light. This suggests that blue light therapy helps reduce high bilirubin levels that cause neonatal jaundice.

Exposing infants to high levels of colored light changes trans-bilirubin to the more water soluble cis-form which is excreted in the bile. Scientists studied 616 capillary blood samples from jaundiced newborn infants. These samples were randomly divided into three groups. One group contained 133 samples and would receive phototherapy with blue light. Another group contained 202 samples would receive room light, or white light. The final group contained 215 samples, and were left in a dark room. The total bilirubin levels were checked at 0, 2, 4, 6, 24, and 48 hours. There was a significant decrease in bilirubin in the first group exposed to phototherapy after two hours, but no change occurred in the white light and dark room group. After 6 hours, there was a significant change in bilirubin level in the white light group but not the dark room group. It took 48 hours to record a change in the dark room group’s bilirubin level. Phototherapy is the most effective way of breaking down a neonate’s bilirubin.

Phototherapy works through a process of isomerization that changes trans-bilirubin into the water-soluble cis-bilirubin isomer.

In phototherapy, blue light is typically used because it is more effective at breaking down bilirubin (Amato, Inaebnit, 1991). Two matched groups of newborn infants with jaundice were exposed to intensive green or blue light phototherapy. The efficiency of the treatment was measured by the rate of decline of serum bilirubin, which in excessive amounts causes jaundice, concentration after 6, 12 and 24 hours of light exposure. A more rapid response was obtained using the blue lamps than the green lamps. However, a shorter phototherapy recovery period was noticed in babies exposed to the green lamps. Green light is not commonly used because exposure time must be longer to see dramatic results. Green light is not commonly used because it makes the babies appear sickly, which is disturbing to observers.

Ultraviolet light therapy may increase the risk of or skin moles, in childhood. While an increased number of moles is related to an increased risk of skin cancer, it is not ultraviolet light that is used for treating neonatal jaundice. Rather, it is simply a specific frequency of blue light that does not carry these risks.

Increased feedings help move bilirubin through the neonate’s metabolic system.

The light can be applied with overhead lamps, which means that the baby's eyes need to be covered, or with a device called a Biliblanket, which sits under the baby's clothing close to its skin.

Brief exposure to indirect sunlight each day and increased feeding are also helpful. A newborn should not be exposed to directsunlight because of the danger of sunburn, which is much more harmful to a newborn's thin skin than that of an adult.

If the neonatal jaundice does not clear up with simple phototherapy, other causes such as biliary atresia, PFIC, bile duct paucity, Alagille's syndrome, alpha 1 and other pediatric liver diseases should be considered. The evaluation for these will include blood work and a variety of diagnostic tests. Prolonged neonatal jaundice is serious and should be followed up promptly.

Exchange transfusions

Much like with phototherapy the level at which exchange transfusions should occur depends on the health status and age of the newborn. It should however be used for any newborn with a total serum bilirubin of greater than 428 umol/l ( 25 mg/dL ).