New therapy blocks newborn jaundice.

New therapy blocks newborn jaundice 

A novel technique for managing jaundice in newborn infants is proving successful in clinical trials, researchers report. The experimental procedure, which involves injecting a synthetic blood protein into affected babies soon after birth, may greatly simplify treatment of one of the most frequent and troubling complications to occur during an infant's first few days of life.

Newborn jaundice is the result of an abnormal accumulation of bilirubin, a yellow pigment that is one of the breakdown products of hemoglobin, the oxygen-carrying component of blood. It occurs when unusually large amounts of a newborn's red blood cells are destroyed, such as when the newborn's blood type is incompatible with its mother's. It also occurs frequently in normal premature infants, and in some full-term babies, because the immature liver is incapable of clearing even normal levels of bilirubin from the blood. If not treated promptly, newborn jaundice, or hyperbilirubinemia, can result in permanent brain damage.

Currently, therapy involves keeping the infant for several days in a special chamber bathed in ultraviolet light, which speeds the breakdown of bilirubin into harmless by-products. More severe cases require blood transfusions. But these therapies are less than ideal. Light chambers can cause dehydration, interfere with digestion and require that the baby be separated from the mother during the first few days of life; blood transfusions are even more traumatic.

Now researchers report they can halt bilirubin formation before levels get high enough to require such treatments.

Working under the direction of Attallah Kappas, physician-in-chief at Rockefeller University Hospital in New York City, a research team designed a synthetic protein, called Sn-protoporphyrin, that mimics hemoglobin in the blood but that contains tin instead of iron as its central metal atom. The pseudo-hemoglobin binds to the enzyme that normally converts hemoglobin to bilirubin, preventing real hemoglobin from interacting with the enzyme. Thus hemoglobin is excreted without ever getting converted to bilirubin.

"This is the first approach that tries to deal with the formation of bilirubin rather than trying to remove the formed product," says George Drummond, one of the researchers. "The beauty is that we're using a synthetic compound that is later excreted in the bile, and the amounts you have to give are very, very small."

After years of studies on animals and on adults suffering jaundice due to liver disease, the researchers recently treated 53 newborn, full-term infants with jaundice due to blood-group incompatibility. Those trials, performed in Greece and reported in the April PEDIATRICS, reduced bilirubin levels by as much as 34 percent and cut the need for ultraviolet therapy more than 40 percent.

The only side effects reported were transient redness of the skin in two infants who received the bilirubin enzyme inhibitor and light treatment concurrently. The researchers say those effects may be eliminated by changing slightly the wavelenghts of ultraviolet light used in those cases.

"Pediatricians have long dreamed of the day when the bilirubin problem would be solved and they would be free of the constant worry about `what to do for a certain level of serum bilirubin,'"says Jerold F. Lucey, editor of PEDIATRICS, in a commentary accompanying the research report. The new treatment, which he calls an important "first step" toward fulfilling that dream, "...represents a promising and new approach to the prevention of neonatal hyperbilirubinemia."