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Neonatal jaundice
Published in Samar Razaq, Difficult Cases in Primary Care, 2021
Infants who present with jaundice in the first 24 hours of their life or beyond 14 days usually require further investigations. Jaundice in the first 24 hours is likely to represent haemolytic disease of the newborn, congenital or postnatal infection, excessive red cell breakdown (e.g. due to a cephalhaematoma) or rare deficiencies of enzymes involved in bilirubin metabolism. Jaundice persisting beyond 14 days may still be physiological breast milk jaundice but may represent persistent infection, serious liver disease, galactosaemia (inability to metabolise galactose) or thyroid problems. When bilirubin levels are measured, the laboratory will normally report back with conjugated and unconjugated levels. A rise in conjugated levels, although not dangerous, is almost always indicative of disease.
Liver Diseases
Published in George Feuer, Felix A. de la Iglesia, Molecular Biochemistry of Human Disease, 2020
George Feuer, Felix A. de la Iglesia
Within the boundaries of the hepatocellular plasma membrane, this type of jaundice is associated with premicrosomal, microsomal, postmicrosomal, or general cytoplasmic defects. In the premicrosomal form, bilirubin conjugation is impaired resulting in an increased unconjugated pigment level in the serum. Jaundice also may be due to a familial hereditary abnormality of bilirubin metabolism as in Gilbert’s syndrome. This autosomal dominant disease is not uncommon and probably represents a heterogenous group of benign disorders or may be the final outcome of several unrelated lesions. This syndrome is characterized by failure of bilirubin transport indicated by mild unconjugated hyperbilirubinemia between 1 to 4 mg/dl. There is an impaired bilirubin uptake by the hepatocytes, the bile composition is normal, and the fecal urobilinogen excretion is either unaltered or only slightly reduced. Liver function tests are normal and there are no significant structural abnormalities. The Gunn strain of rat exhibits similarities to the symptoms of Gilbert’s syndrome.12 This mutant strain of rats develops a hereditary jaundice with autosomal recessive characteristics.
Principles of Clinical Pathology
Published in Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard, Toxicologic Pathology, 2018
Niraj K. Tripathi, Jacqueline M. Tarrant
In contrast to serum liver enzyme activities, serum total bilirubin concentration can be a measure of liver function. In the absence of a significant hemolytic process, increased serum bilirubin concentration indicates general hepatic dysfunction due to hepatocellular injury; bile retention due to cholestasis; or altered bilirubin metabolism due to interference with the normal processes of bilirubin uptake, conjugation, secretion, and excretion. Secretion of conjugated bilirubin across the canalicular membrane is the rate-limiting step, and small amounts of conjugated or direct bilirubin normally escape into plasma. In contrast to unconjugated bilirubin, conjugated bilirubin is not bound to albumin, is freely filtered by the glomerulus, and can sometimes be detected in concentrated urine in the absence of toxicity or disease, especially in dogs.
Recognizing skin conditions in patients with cirrhosis: a narrative review
Published in Annals of Medicine, 2022
Ying Liu, Yunyu Zhao, Xu Gao, Jiashu Liu, Fanpu Ji, Yao-Chun Hsu, Zhengxiao Li, Mindie H. Nguyen
Jaundice (Figure 3(c)) describes discolouration of the skin, sclera and mucous membranes that is attributable to the accumulation of bilirubin and its metabolites in the tissues. Jaundice generally begins to become visible when the concentration of serum bilirubin surpasses about 2 mg/dL (34 mmol/L). The colour of the skin varies from lemon yellow to apple green, gradually evolving as the serum bilirubin level becomes elevated. According to the presence of conjugated or unconjugated components of bilirubin, we can classify the three major groups of underlying causes of jaundice: prehepatic, intrahepatic or post-hepatic. Prehepatic jaundice involves haemolytic anemias, which can also be seen in neonatal physiological jaundice and breast milk jaundice. Intrahepatic jaundice involves both conjugated and unconjugated hyperbilirubinemia resulting from liver failure-associated severe acute hepatitis or cirrhosis. Other intrahepatic causes of hyperbilirubinemia include intrahepatic cholestatic diseases, such as PBC and the various congenital genetic disorders involving bilirubin metabolism or transport such as Gilbert, Crigler–Najjar syndrome, or Dubin-Johnson syndrome. Post-hepatic jaundice involves conjugated hyperbilirubinemia arising from extrahepatic issues, such as biliary tract obstruction [1].
The relationship between UGT1A1 gene & various diseases and prevention strategies
Published in Drug Metabolism Reviews, 2022
Dan Liu, Qi Yu, Qing Ning, Zhongqiu Liu, Jie Song
UGT1A1 metabolism and detoxification of bilirubin is an important physiological process in the body. The above has given a detailed overview of many related diseases caused by bilirubin metabolism disorders. Therefore, the biomolecular mechanism of the interaction between bilirubin and UGT1A1 is essential for in-depth knowledge of disease occurrence and prevention and treatment of diseases. However, the eutectic structure of UGT1A1 and bilirubin has not been resolved. In our previous studies, we construct the interaction relationship between UGT1A1 and bilirubin through molecular docking (Figure 4) (Liu et al. 2021). The 65S, 67Y, 69R, and 119D residues of UGT1A1 are responsible for the recognition of bilirubin; 38S, 39H, 221 F, 374 G, 394 F, and 396 D are responsible for the recognition of UDPGA. Among them, the 65S, 67Y, and 69 R residues are located near 71 G. A short-chain glycine (71 G) becomes the long-chain arginine, the side chain increases the steric hindrance of bilirubin toward UDPGA, which restricts the role of amino acids in the recognition pocket, leading to decline in activity.
A Neglected and Promising Predictor of Severe Hyperbilirubinemia Due to Hemolysis: Carboxyhemoglobin
Published in Fetal and Pediatric Pathology, 2020
Birol Karabulut, Baran Cengiz Arcagok
As with all such metabolites, a production–excretion balance exists during bilirubin metabolism. However, this balance may deteriorate owing to increased production or decreased excretion [1]. A decrease in the production of fixed excretion leads to developmental jaundice, while an increase in production can cause pathological jaundice. Developmental jaundice in newborns occurs at day 3–5 and peaks during days 3–7. Developmental jaundice is caused by aged fetal erythrocytes, immature uridine 5′-diphospho-glucuronyltransferase activity, and intestinal flora due to the β-glucuronidase enzyme function in breast milk; the total serum bilirubin (TSB) level may be as high as 17 mg/dl [2]. Pathological jaundice due to increased bilirubin production leads to earlier and higher levels of TSB, with abnormalities ranging from the subtle changes of bilirubin-induced neurologic dysfunction (BIND) to the most extreme cases of reversible acute bilirubin encephalopathy or the chronic, irreversible changes of kernicterus [3]. Regardless of the cause, the risk status should be determined before newborns are discharged from the hospital, and early detection is required to predict the peak value of bilirubin and prevent neurological dysfunction.