Fasting Serum Bile Acid Concentrations Research Articles

Delta 4-3-oxosteroid 5 beta-reductase deficiency described in identical twins with neonatal hepatitis. A new inborn error in bile acid synthesis.

A new inborn error in bile acid synthesis, manifest in identical infant twins as severe intrahepatic cholestasis, is described involving the delta 4-3-oxosteroid 5 beta-reductase catalyzed conversion of the key intermediates, 7 alpha-hydroxy-4-cholesten-3-one and 7 alpha,12 alpha-dihydroxy-4-cholesten-3-one for chenodeoxycholic and cholic acid synthesis, to the respective 3 alpha-hydroxy-5 beta (H) products. This defect was detected by fast atom bombardment ionization-mass spectrometry from an elevated excretion and predominance of taurine conjugated unsaturated hydroxy-oxo-bile acids. Gas chromatography-mass spectrometry confirmed these to be 7 alpha-hydroxy-3-oxo-4-cholenoic and 7 alpha,12 alpha-dihydroxy-3-oxo-4-cholenoic acids (75-92% of total). Fasting serum bile acid concentrations were greater than 37 mumol/liter; chenodeoxycholic acid was the major bile acid, but significant amounts of allo(5 alpha-H)-bile acids (approximately 30%) were present. Biliary bile acid concentration was less than 2 mumol/liter and consisted of chenodeoxycholic, allo-chenodeoxycholic, and allo-cholic acids. These biochemical findings, which were identical in both infants, indicate a defect in bile acid synthesis involving the conversion of the delta 4-3-oxo-C27 intermediates into the corresponding 3 alpha-hydroxy-5 beta(H)-structures, a reaction that is catalyzed by a delta 4-3-oxosteroid-5 beta reductase enzyme. This defect resulted in markedly reduced primary bile acid synthesis and concomitant accumulation of delta 4-3-oxo-and allo-bile acids. These findings indicate a pathway in bile acid synthesis whereby side chain oxidation can occur despite incomplete alterations to the steroid nucleus, and lend support for an active delta 4-3-oxosteroid 5 alpha-reductase catalyzing the conversion of the delta 4-3-oxosteroid intermediates to the respective 3 alpha-hydroxy-5 alpha(H)-structures.

Thallium-201 per rectum for the diagnosis of cirrhosis in patients with asymptomatic chronic hepatitis

In normal subjects, thallium-201, administered per rectum, is taken up mainly by the liver (heart/liver ratio in normal subjects: 0.04 to 0.12). It has been claimed that an increased heart/liver ratio is suggestive of portal-caval shunting and portal hypertension. To evaluate the possibility of using thallium-201 as a test to diagnose cirrhosis, we administered this substance per rectum to 33 patients with biochemical evidence, but no clinical symptoms, of liver disease. Laparoscopy and liver biopsy revealed chronic active hepatitis without cirrhosis in 18 patients, and chronic active hepatitis with cirrhosis in the others. The results of conventional liver function tests were similar in both groups. A significant difference, however, was found between the means of fasting serum bile acid concentrations (9.8 +/- 3.2 and 18.3 +/- 4.2 microM per liter) in chronic active hepatitis without cirrhosis and cirrhotic patients, and between the means of the heart/liver ratios 20 min after thallium-201 administration (heart/liver: 0.09 +/- 0.03 and 0.54 +/- 0.13, respectively). Unlike the serum bile acid concentration which gave some overlapping values, the thallium-201 test clearly distinguished the chronic active hepatitis without cirrhosis group from the cirrhotics. In the cirrhotic group, there was a significant correlation between the heart/liver ratio and signs of portal hypertension such as esophageal varices, increased diameter of the vena porta and hypersplenism. The thallium-201 test is therefore useful in discriminating between chronic active hepatitis with and without cirrhosis in clinically asymptomatic subjects with biochemical evidence of moderate liver function impairment. A heart/liver uptake ratio much higher than normal (above 0.30) strongly suggests the development of hepatic cirrhosis.

Conjugated bile acids in serum and secretions in response to cholecystokinin/secretin stimulation in children with cystic fibrosis.

More than 80% of patients with cystic fibrosis have poor pancreatic function, and have large daily faecal bile acid losses. This has been postulated to lower luminal bile acid concentrations and adversely affect fat absorption. We studied, for the first time, quantitative individual conjugated duodenal bile acid secretion rates into the duodenum during cholecystokinin/secretin infusion in 55 cystic fibrosis patients and six controls, using a quantitative non-absorbable marker technique. We were able to show adequate duodenal total bile acid concentrations and normal secretion rates in these children. The bile acid secretion pattern in cystic fibrosis patients showed a marked increase in bile acid concentration during cholecystokinin/secretin infusion, to levels which were above the critical micellar concentration indicating that the gall bladder is a functional organ in this disease. The subsequent fall in secretion rate was similar to controls. We have documented a significantly raised glycine/taurine bile acid conjugation ration in duodenal juice from cystic fibrosis patients and suggest that the combined effects of lowered ileal pH and increased glycine conjugated proportion of bile acids may cause precipitation of bile acids leading to decreased fat absorption and large faecal bile acid losses. To further investigate bile acid secretion in children with cystic fibrosis, we modified the high performance thin layer chromatography/densitometry method to enable measurement of individual glycine and taurine conjugates in serum. In comparing cystic fibrosis patients and controls, we were able to determine a group of 18 (36%) with bile acid evidence of liver damage who also showed reduced bile acid secretion into the duodenum. We were unable to study changes in serum bile acids during cholecystokinin/secretin infusion because of the high level of bile acid contamination in Boots Secretin. Some patients showed raised fasting serum bile acid concentrations more than two years before changes in conventional liver function tests or clinically evident liver disease. We have shown fasting serum bile acids to be a sensitive measure of liver dysfunction in cystic fibrosis and postulate that raised proportions of glycine conjugated bile acids may be responsible for the high incidence of liver disease in cystic fibrosis.

Electron microscopic studies of human haemosiderin and ferritin.

Ferritin and haemosiderin were isolated from fresh frozen human spleens that had been removed from patients with secondary iron overload due to multiple transfusions. Haemosiderin was solubilised by a novel technique that maintains its integrity. Unstained preparations of haemosiderin and ferritin were visualised and quantitative measurements made of the volumes of iron core. The mean diameter of the ferritin core (6.4 nm) was larger than that of haemosiderin (5.7 nm). In addition, haemosiderin, in contrast to ferritin, showed a large number of cores of less than 5 nm in diameter. Negatively stained preparations of haemosiderin and ferritin were visualised, confirming the small core size of the haemosiderin. The protein shell of haemosiderin, unlike that of ferritin, was thinner and irregular. These findings are consistent with the suggestion that haemosiderin is derived from ferritin by partial proteolysis and partial solubilisation of the iron core, presumably by lysosomal action.

Serum and urinary bile acids in patients with primary biliary cirrhosis.

Serum concentrations and daily urinary excretions of unsulphated and total cholic (C) and chenodeoxycholic (CDC) acid were determined by radioimmunoassay in 15 patients with primary biliary cirrhosis. Thirteen patients had increased fasting serum bile acid concentrations; two of them had an increase of C only. An increase of C and CDC in serum was always followed by an increased urinary excretion of C and CDC. The individual serum bile acids were separated by gas-liquid chromatography. 3 beta-hydroxy-5-cholenoic acid was increased in nine patients, and its serum concentration was correlated to the total serum bile acid concentration. Deoxycholic (DC) and lithocholic (LC) acid were found in most patients, but their serum concentrations were not correlated to the total serum bile acid concentration. Minor bile acids comprised an average of 2% of the total concentration.

Evaluation of Fasting Serum Bile Acid Concentration in Patients with Liver and Gastrointestinal Disorders

Fasting concentrations of S-cholate, S-chenodeoxycholate, S-aminotransferases, S-bilirubin, S-alkaline phosphatases, and S-glutamyltransferase were determined in 564 outpatients with disorders of the liver and gastrointestinal tract. Unsulphated conjugates of cholic (fS-C) and chenodeoxycholic acid (fS-CDC) were determined by radioimmunoassay. In patients with increased serum bile acid concentrations fS-C and fS-CDC were linearly correlated, and the fS-C/fS-CDC ratio was similar in all patient groups. The incidence of false-positive results of fS-CDC was probably due to inadequate fasting and comparison of fS-C only with the liver tests. In 51 patients with verified cirrhosis fS-C was significantly correlated with S-bilirubin in a semilogarithmic relation but not with S-alkaline phosphatases or S-glutamyltransferase. fS-C was found to be a sensitive indicator of liver disease in the anicteric stage. Of 207 patients with inflammatory bowel disease, 63 had 1 or several of the results of liver tests for cholestasis elevated. There was no correlation between the different tests. In these patients and all patients with gastrointestinal disorders the commonest single finding was an elevation of S-alkaline phosphatases not associated with cholestasis.

Within-day fluctuations in serum bile-acid concentrations among normal control subjects and patients with hepatic disease.

Under carefully controlled conditions in a clinical research ward, conjugated primary bile-acid concentrations were measured by a 125I-radioimmunoassay every eight hours for four days in seven healthy control subjects and ten patients with hepatic disease (five with cirrhosis, three with primary biliary cirrhosis and two with sclerosing cholangitis). Two meals of approximately equal composition were consumed daily at 10 A.M. and 6 P.M., and blood was drawn at 4 A.M., 12 noon and 8 P.M.. With the exception of one patient, all subjects had greater postprandial than fasting serum bile-acid concentrations, with all healthy control subjects and most of those with hepatic disease showing evening values equal to or greater than the noon values. For the healthy control subjects, the mean values were 0.8, 1.4 and 1.9 microM, and for those with hepatic disease, 108, 140 and 133 microM. There were large fluctuations in serum bile acids (up to sevenfold) among patients with hepatic disease. These fluctuations were independently validated by finding corresponding changes in serum radioactivity derived from injection of a tracer (24-14C cholic acid) at the start of each study. To be consistent, especially for serial measurements, bile acids should be measured in blood taken at the same time of the day and at the same time relative to meals.

Serum Bile Acid Concentrations in Patients with Liver Disease

An enzymatic-fluorimetric method using a highly purified 3alpha-hydroxysteroid dehydrogenase (Sterognost-3alpha, Nyco) was used to determine fasting serum bile acid concentrations on 49 occasions in 43 patients with various liver diseases. A two-hour postprandial bile acid determination was carried out on 29 occasions in 27 of the patients. Fasting bile acid concentration correlated significantly both in cholestatic hepatobiliary and in parenchymatous liver disease to serum bilirubin and aspartate aminotransferase (ASAT) but not to alanine aminotransferase (ALAT), alkaline phosphatase, or albumin. The two-hour postprandial bile acid concentration was above normal in all patients with biochemical and/or histological signs of hepatobiliary disease, also when fasting concentration was within normal limits. In parenchymatous liver disease correlations existed between the two-hour postprandial bile acid concentration and bilirubin, ASAT, and ALAT. The sensitivity of serum bile acid estimation was compared to other liver function tests. Both the fasting and the postprandial serum bile acid concentrations tended to be more sensitive tests of hepatobiliary disease than bilirubin, ASAT and ALAT.

Diagnositic value of serum bile acid estimations in liver disease.

Bile acid concentrations were estimated enzymatically in fasting and postprandial (two-hour) serum samples from 18 normal subjects and 30 patients with histologically proven hepatobiliary disease. The serum bile acid concentration was less than 15 mumol/1 in normal subjects and did not increase postprandially. The fasting serum bile acid concentration was raised in 27 of the patients with hepatobiliary disease, and following a meal was outside the normal range in all 30 patients. Other liver function tests were abnormal less frequently. These results suggest that the estimation of serum bile acids in the postprandial state is a sensitive screening test of hepatobiliary disease. They should be of particular value in patients in whom liver disease is suspected but not proven, and in those recovering from liver disease, especially following therapy.

Liver structure and function in cholelithiasis: effect of chenodeoxycholic acid.

Although, in suitable patients, oral chenodeoxycholic acid (CDCA) dissolves gallstones, the results of recent animal studies suggest that it might be hepatotoxic. Liver function was therefore studied in patients with gallstones before and during treatment with CDCA and liver biopsies were carried out both in patients with cholelithiasis given bile acid therapy and in those who had been given no medical treatment. In 25 patients treated with 0.5-1.5 g CDCA/day (7-20 mg kg body weight(-1) day(-1)) there was no significant change in serum bilirubin, albumin, globulin, transaminase, isocitric dehydrogenase, alkaline phosphatase, and gamma glutamyl transpeptidase levels before and at monthly intervals during six months' treatment. The kinetics of bromsulphthalein (BSP) clearance and its apparent transport maximum were not significantly changed during CDCA therapy. The mean fasting serum bile acid concentrations of 18.0 +/- SEM 1.2 mumoles/litre before and 20.0 +/- 3.5 mumoles/litre during treatment were both significantly greater than control values. Liver histology was not appreciably different in 11 patients treated with CDCA from that in eight patients with untreated cholelithiasis and in three patients who had received CDCA three to four months before biopsy. These results suggest that in doses of 0.5 to 1.5 g/day CDCA is not hepatotoxic in man.