Vàng da thường rõ ràng đầu tiên vào mặt và sau đó sau một sự tiến triển cephalocaudal như mức độ tăng vàng da. Lòng bàn tay và lòng bàn chân người cuối cùng được vàng da và cho thấy vàng da nặng và trẻ sơ sinh một nguy cơ cho bệnh não bilirubin. Trong trường hợp không có tổn thương thần kinh | 112 SECTION 3 NEONATAL CRITICAL CARE Jaundice is typically apparent first in the face and then follows a cephalocaudal progression as the degree of jaundice increases. Palms and soles are the last to be jaundiced and suggest severe jaundice and an infant at risk for bilirubin encephalopathy. In absence of neurologic injury unconjugated hyperbilirubinemia is not associated with any specific symptoms except symptoms related to underlying etiology. Physiologic jaundice in term infants is characterized by a progressive rise in serum bilirubin to a mean peak of 5-6 mg dL by the third day of life in both White and Black infants and to a peak of 10-14 mg dL by the fifth day in oriental infants. This peak is followed by a gradual decline to baseline by the fifth day of life in White and Black infants and by the seventh to the tenth day in oriental infants. Physiologic jaundice in a preterm infant appears earlier can reach a higher peak and declines more gradually. The underlying mechanisms for physiologic jaundice in newborn are related to a increased bilirubin production because of larger RBC mass and shorter life span b hepatic immaturity resulting in defective uptake diminished conjugating capacity and impaired excretion and c increased enterohepatic circulation in newborn. Pathologic jaundice is diagnosed when there is clinical jaundice in the first 24 hours of life or serum bilirubin level increasing at a rate of 5 mg dL day. A peak serum bilirubin level higher than that mentioned above in a term infant and 15 mg dL in a preterm infant should always be considered pathologic until proven otherwise. 1. Most disorders causing unconjugated hyperbilirubinemia do so via one or more of the same mechanisms that produce physiologic jaundice described above. 2. The most common pathologic cause of increased bilirubin production in the newborn is isoimmune hemolytic disease because of blood group incompatibility between mother and fetus. Other causes of hemolysis as mentioned .
