Bile acid levels may predict outcome of Kasai surgery for biliary atresia
Elevated bile acids after surgery associated with higher risk of complications
Measuring the blood levels of bile acids, the main component of the digestive fluid bile, can help predict key clinical outcomes for babies with biliary atresia after they undergo standard Kasai surgery to restore bile flow, according to a study in Finland.
High bile acid levels were significantly associated with a fourfold higher risk of portal hypertension, which is a liver complication marked by high blood pressure in a major liver vein, and a 12 times higher risk of needing a liver transplant or dying.
Blood “bile acids offer a simple and useful additional tool” to predict Kasai surgery outcomes in biliary atresia, according to researchers.
The study, “Serum bile acids early after portoenterostomy are predictive for native liver survival and portal hypertension in biliary atresia,” was published in the Journal of Pediatric Gastroenterology and Nutrition.
With biliary atresia, a newborn’s bile ducts, or the tubes that transport bile from the liver to the intestines, are absent or blocked. This prevents bile from draining from the liver to the small intestine, resulting in toxic bile buildup in the liver, causing damage and bile leakage into the bloodstream.
Biliary atresia symptoms include dark urine, pale stools, and jaundice, or yellowing of the skin and whites of the eyes.
Kasai procedure to restore bile flow
The first-line treatment is the Kasai procedure, or Kasai portoenterostomy, a surgery that aims to restore bile flow by creating an alternate route into the small intestine that bypasses the blocked ducts. More than half of patients no longer have jaundice after the surgery, indicated by normalization of blood bilirubin levels within six months. Bilirubin is an orange-yellow pigment of bile that accumulates in the blood in biliary atresia and is thought to underlie jaundice.
However, the Kasai procedure doesn’t always result in a successful outcome in restoring bile flow, and some children will continue to experience liver damage, which can eventually progress to liver failure, where a liver transplant is the only therapeutic option.
About one in five biliary atresia patients will need a liver transplant before they turn 2, and half before adulthood. In addition, more than two-thirds develop serious liver complications like portal hypertension before school age.
However, “there is a need for reliable, early markers of liver disease progression in biliary atresia,” the researchers wrote.
To evaluate the predictive value of blood bile acid levels on post-Kasai clinical outcomes, a team of researchers in Finland reviewed bile acids, bilirubin, and clinical data from 56 babies with biliary atresia who underwent the surgery.
On average, babies were 58 days old at the time of surgery. Three-quarters no longer had jaundice after six months.
During follow-up, 36 children (64%) were diagnosed with portal hypertension at the median age of 2.1 years. At the latest follow-up, 52% of the children were still living with their native liver, while were 41% had undergone liver transplant; no child was listed for liver transplant.
Median transplant-free survival was 6.3 years
Median transplant-free survival was 6.3 years among all the children and 7.5 years among those who no longer had jaundice.
Both bile acids and bilirubin, measured in the blood at three and six months after surgery, accurately predicted survival without the need for a liver transplant in all children. For those who became free of jaundice, bile acids at one month were the strongest predictor of transplant-free survival.
Blood bile acid levels greater than 150 micromoles per liter at three months after surgery significantly increased by eight times the risk of needing a liver transplant or dying. High levels of bilirubin (greater than 18.5 micromoles per liter) significantly increased this risk by seven times.
Among children whose jaundice cleared, only elevated bile acids (higher than 119 micromoles per liter) at three months after surgery were a significant predictor of liver transplant or death, increasing the risk by 12 times.
Elevated levels of bile acids and bilirubin in the blood at three and six months also increased the risk of developing portal hypertension by four and 13 times, respectively, predicting the complication with “moderate accuracy” in babies who had become free of jaundice.
The researchers noted that larger studies in biliary atresia are needed to validate the cutoffs and to investigate the role of bile acids in various liver disease complications.
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