The cholestatic syndrome--1971

Dyslipoproteinaemia of liver disease

Hepatic diseases differ from most other causes of secondary dyslipidaemia in that the circulating lipoproteins are not only present in abnormal amounts but they frequently also have abnormal composition, electrophoretic mobility and appearance. Pre-beta and alpha bands can be absent on electrophoresis in all types of liver disease although material in the VLDL and HDL ranges can be isolated in the ultracentrifuge. Cholestatic liver disease has been the most extensively studied and the hyperlipidaemia can be extreme with marked elevations of free cholesterol and phospholipids. This results largely from the presence of LP-X, an abnormal LDL, with a vesicular structure that appears in rouleaux formation under the electron microscope. It is virtually specific for cholestasis and familial LCAT deficiency. The LDL, however, is heterogeneous and may also contain a large triglyceride-rich particle (LP-Y) as well as more normal-looking particles, which are none the less depleted in cholesteryl esters and rich in triglycerides. Indeed, when patients with cholestasis are hypertriglyceridaemic the excess triglyceride is to be found predominantly in these two LDL fractions rather than in VLDL. HDL in cholestasis may contain disc-like particles, similar to those newly secreted by the liver and intestine, as well as more normal-looking spherical particles. In extrahepatic obstruction concentrations of HDL and its major apolipoproteins, apoAI and apoAII, are frequently reduced, although a subfraction rich in apoE is often found. In all but the latest stages of chronic intrahepatic cholestasis due to primary biliary cirrhosis, however, HDL, especially HDL2, concentrations are increased, probably due to the presence of a circulating inhibitor of HL. Many of these lipoprotein changes found in cholestasis resemble those of familial LCAT deficiency, although the hyperlipidaemia is not usually so severe in the latter condition. Indeed, in patients with cholestasis but well-preserved LCAT activity many of the characteristic lipoprotein changes, such as LP-X, LP-Y and discoidal HDL, may not be seen. In acute hepatocellular disease, such as alcoholic or viral hepatitis, it is not unusual for the patient to go through a cholestatic phase and many of the same lipoprotein changes may be seen. In cirrhosis without cholestasis the patients are not usually significantly hyperlipidaemic and in advanced cases cholesterol and apoB levels may be reduced. Although LCAT activity and the proportion of plasma cholesterol esterified may also be markedly reduced, LP-X is not usually seen, possibly because the flux of free cholesterol and phospholipid (lecithin), the LCAT substrates, is relatively low. Discoidal HDLs are often present.(ABSTRACT TRUNCATED AT 400 WORDS)

Urinary bile acids in late pregnancy and in recurrent cholestasis of pregnancy

The metabolic profiles of urinary bile acids in pregnant women in the last trimester and patients with recurrent intrahepatic cholestasis of pregnancy (RCP) were studied. Following separation according to mode of conjugation, about thirty different bile acids were quantitatively analysed by gas chromatography-mass spectrometry. In all patients the sulphate fraction comprised 50--90% of the total bile acids. In RCP a shift from glycine to taurine conjugation was noted to together with a slight relative increase in sulphation. A ten- to hundred-fold increase in cholic and chenodeoxycholic acids was seen in RCP, the increase being mainly in the sulphate fraction. Tetrahydroxylated bile acids, tentatively regarded as 1- and 6-hydroxylated products of cholic acid, were quantitatively important in patients with RCP. The relative amounts of the secondary bile acids, deoxycholic and lithocholic acids, decreased with increasing cholestasis. Metabolites hydroxylated at C-6 were common, and the excretion of hydroxylated at C-6 were common, and the excretion of hyocholic acid was positively correlated to that of chenodeoxycholic acid. An increase in the excretion of 5 alpha-configurated bile acids in RCP was noted. A positive correlation between the excretion of 3 beta-hydroxy-5-cholenoic acid and 3 beta,12 alpha-dihydroxy-5-cholenoic acid indicates a metabolic relationship between the two compounds. Because of the relatively small amounts of lithocholic and 3 beta-hydroxy-5-cholenoic acids in patients with RCP, these compounds do not seem to be of pathogenetic importance in this type of cholestasis.

Urinary bile acids during development of recurrent cholestasis of pregnancy

The pregnancies of two patients with mild intrahepatic cholestasis of pregnancy (RCP) were followed with detailed analyses of bile acids in urine. About twenty-five different bile acids were determined by GC/MS following separation according to mode of conjugation. The results were collated with the clinical course of the disease. The first detectable change in bile acid excretion was the appearance of tetrahydroxylated bile acids at about the 30th gestational week. Somewhat later and concomitant with the rise in urinary oestriol, the total bile acid excretion started to increase. In one of the patients, who had a maximum total excretion of 84 mumol/24 h, deoxycholic acid was a major constituent, comprising about 40% of the total. The same patient had only slightly elevated levels of tetrahydroxylated bile acids and serum amino-transferases. The possible effect of low-fat diet on these results is discussed. Monohydroxylated bile acids were present throughout the pregnancies in small amounts and their role as aetiological factors is discussed. The care of RCP patients is outlined, and the need for simple, specific and quantitative methods for following the course of RCP is pointed out.

Jaundice in pregnancy--1976

An integrative survey is given of three disease processes, in which recent progress of a fundamental nature has been made, primarily affecting the liver, either coincident with or caused by the gravid state. The three conditions considered include (1) recurrent cholestasis of pregnancy (RCP), (2) viral hepatitis coincident with pregnancy, and (3) acute fatty liver of pregnancy (AFLP). In addition to an assessment of our present knowledge with respect to RCP and AFLP, new genetic hypotheses are proposed. In the latter, the proposal of an ornithine transcarbamylase deficiency, similar to that seen in Reye's syndrome, has potential therapeutic implications that are explored. In light of the currently available information on the interaction between maternal viral hepatitis and the variant forms of vertical maternal-fetal transmission, tentative recommendations regarding management of the newborn are suggested.

Bile salts and liver disease in childhood

Recognition of neonatal liver disease has been heavily dependent on the occurrence of jaundice. In most instances the jaundice is related to specific disturbances in bilirubin transport and other tests of liver function are normal. In contrast, hepatitis and other liver diseases not specifically affecting bilirubin transport often go undetected unless jaundice occurs.

The development of practical methods for the estimation of bile acids in serum has permitted an evaluation of hepatic excretory function in neonates and children independent of bilirubin excretion. Since bile acid excretion by the liver each day greatly exceeds bilirubin excretion it was not surprising to find that elevations in serum bile acids occur regularly in anicteric hepatitis. Because the excretion of bile acids generates canalicular bile flow a reduction in the capacity to excrete bile acids intimates the presence of cholestasis. Early cholestasis is not associated with hyperbilirubinaemia but as cholestasis becomes more severe, jaundice occurs and the possibility of biliary atresia arises in neonates. Serum bile acid patterns in neonates being evaluated for biliary atresia indicate two distinctive patterns. Those infants with severe cholestasis and patent bile ducts usually have pre-dominantly cholic acid in serum. This observation is consistent with the bile acid patterns found in intrahepatic and extrahepatic cholestasis occurring in adult life. Infants found to have extrahepatic biliary atresia have marked elevations in the proportion of chenodeoxycholate in serum. Since elevations of chenodeoxycholate in serum are associated with hepatitis, the findings are consistent with the view that extrahepatic atresia is a rare sequalae of hepatitis.

Studies of bile acid metabolism and excretion give promise of providing further insight on the pathogenesis of cholestatic liver disease.