An elevated result from a liver enzyme test in an infant can cause concern. Liver enzymes, primarily Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST), are proteins inside liver cells that assist in processes like protein breakdown and energy conversion. When liver cells are damaged due to inflammation or injury, these enzymes leak into the bloodstream, which is what a blood test measures. High enzyme levels signal liver cell stress, but interpretation in newborns differs from adults because the normal range for infants is often naturally higher and changes rapidly with age.
Transient and Physiological Elevations
Not every elevated enzyme result indicates a serious underlying disease, as some increases are temporary responses to the stresses of birth and early life. The transition from the womb to the outside world is a physiological event that can cause mild, transient enzyme elevations. This is often seen immediately following a difficult or prolonged delivery, a period of perinatal stress.
Physiological jaundice also contributes to temporary liver stress. This benign condition is caused by the newborn’s immature liver enzyme systems struggling to process bilirubin, a waste product from red blood cell breakdown. While physiological jaundice primarily raises bilirubin levels, the associated hepatic immaturity can sometimes cause a mild, short-lived rise in transaminases like AST and ALT. These elevations are generally short-lived, resolving on their own within the first few weeks of life, requiring only monitoring to confirm their downward trend.
Infectious Causes of Liver Inflammation
A more concerning cause of enzyme elevation is acute inflammation of the liver, known as hepatitis, resulting from an infection. Infants can acquire various pathogens either before birth (in utero) or during the delivery process. These infections directly damage liver cells, causing a significant release of enzymes into the bloodstream.
One group of pathogens frequently screened for is the TORCH complex, which includes Cytomegalovirus (CMV) and Herpes Simplex Virus (HSV). Congenital CMV infection is a common cause of infectious hepatitis in newborns and can lead to persistently high liver enzyme levels alongside symptoms like jaundice and hepatosplenomegaly. HSV, typically acquired during passage through the birth canal, can cause severe, widespread infection, including acute liver failure and extremely high enzyme levels. Generalized bacterial infections, or sepsis, can also cause liver cell injury as part of a systemic inflammatory response, leading to a spike in transaminases.
Structural and Inherited Metabolic Disorders
Persistent or significantly high liver enzyme levels often point toward issues related to the liver’s physical structure or genetic defects affecting its metabolic functions. Biliary Atresia is a serious structural condition where the bile ducts are blocked or absent, preventing bile from draining into the intestine. This backup of bile is toxic to liver cells, leading to inflammation, scarring, and high enzyme levels. It typically becomes apparent within the first two to eight weeks of life with persistent jaundice and pale, clay-colored stools.
Inherited metabolic disorders represent another category of chronic liver injury where a genetic defect disrupts the liver’s chemical processing abilities. Alpha-1 Antitrypsin (A1AT) deficiency is a genetic condition where the liver produces a misfolded protein that gets trapped inside the liver cells. This accumulation causes cellular stress and eventual damage.
Galactosemia is a disorder where the body lacks the enzyme necessary to break down the sugar galactose, a component of lactose found in milk. When an infant consumes milk, toxic byproducts accumulate in the liver, leading to rapid cell damage, liver failure, and high enzyme levels. If not promptly diagnosed, treatment requires a galactose-free diet. These inherited conditions often require specialized genetic testing for diagnosis and targeted long-term management.
Navigating Diagnosis and Monitoring
Once elevated liver enzymes are detected, the healthcare team begins a methodical investigation to determine the cause. The initial step involves a detailed patient history, including a review of the pregnancy, delivery, and any symptoms the baby is experiencing. This is followed by a thorough physical examination to check for signs like jaundice, an enlarged liver, or spleen. This clinical information helps categorize the pattern of liver injury.
Follow-up testing typically includes repeat blood work to track the trend of the enzymes and assess other markers like bilirubin and coagulation factors, which reflect the liver’s function. Imaging studies, such as an abdominal ultrasound, are often performed early to check for structural issues like bile duct blockage, a concern in cases of Biliary Atresia. Specialized blood and urine panels are then used to screen for specific viral infections or inherited metabolic disorders. In complex cases, a consultation with a pediatric gastroenterologist or hepatologist is necessary to guide the diagnostic process and formulate a management plan.