Endogenous bile acid tolerance test for liver function

Bile acids in the diagnosis, pathology, and therapy of hepatobiliary diseases

Bile acids are normally confined in the enterohepatic circulation in which they play an important role in bile formation, biliary lipid excretion, and intestinal lipid absorption. In hepatobiliary diseases, bile acids escape the confinement of the enterohepatic circulation, allowing the measurement of the serum total bile acid concentration as a diagnostic indicator. Accumulation of certain bile acids within the hepatocyte, amplified as a consequence of cholestatic hepatobiliary disease, probably enhances cytotoxicity and leads to secondary pathology. Ursodeoxycholate, a bile acid with atypical physiological effects, may be useful in the treatment of various long-term cholestatic hepatobiliary diseases. Presently, most of the information on the toxicity and therapeutic usefulness of bile acids are based on studies in humans and experimental animals. Further studies, both basic and clinical, are needed to determine the pathologic as well as the therapeutic effects of bile acids in domestic animals.

Liver function studies in children with acute lymphocytic leukemia after cessation of therapy

We investigated liver function in 27 children with acute lymphocytic leukemia (ALL) after cessation of therapy. Induction therapy consisted of prednisolone+vincristine (VP regimen) alone (16 patients) or with addition of daunorubicin (4 patients) or L-asparaginase (7 patients). Patients treated with VP regimen received short courses of VP regimen every 12 weeks for the first year of maintenance. Twenty-five patients remained in first complete remission and had completed 3-year maintenance therapy with methotrexate (MTX) and 6-mercaptopurine (6-MP) 1-7 years prior to this study. Twenty-three patients had received transfusions of packed red blood cells or fresh whole blood (1-11 units; median: 2 units) but none had evidence of either hepatitis B or hepatitis C. Alanine aminotransferase (ALT), which was measured every 3 months during maintenance therapy, had values more than three times the upper limit of the normal range in 25% of the measurements in more than half of the patients. However, by 3 months after the completion of maintenance therapy, ALT had normalized in all patients and remained normal in all but two patients until the time of this study. Serum bilirubin, serum albumin, and prothrombin time were all within normal limits. Fasting and 2-hour postprandial total serum bile acids were high in 5 of 13 patients and in 6 of 13 patients, respectively. The ratio of cholic acids+deoxycholic acids to chenodeoxycholic acids+lithocholic acids was below 1 in all but two patients, whereas this ratio was above 1 in all controls. Our bile acid profile results indicate the necessity of careful long-term follow-up of survivors of ALL treated with hepatotoxic chemotherapy during childhood.

Serum bile acid concentrations in mild liver cirrhosis

Fasting serum conjugated bile salt concentrations were measured in a group of 20 patients with moderate post-hepatitis cirrhosis. Twenty healthy volunteers were used as controls. The individual conjugated bile acids were analyzed by a specific and sensitive method which couples reversed-phase high-performance liquid chromatography with mass spectrometry. Significantly elevated levels of the total and individual conjugated bile acids were found in cirrhotic patients. The predominant serum bile acids were conjugates of chenodeoxycholic acid. The conjugates of lithocholic acid were also increased; in subjects with normal liver function, on the contrary, they were found only in traces.

Determination of individual serum bile acids in chronic liver diseases: fasting levels and results of oral chenodeoxycholic acid tolerance test

Fifteen bile acids in serum of 5 normal subjects and 21 patients with chronic liver diseases were fractionated by high performance liquid chromatography. Fasting total bile acids (TBA), glycocholic acid, taurocholic acid, glycochenodeoxycholic acid (GCDCA), and taurochenodeoxycholic acid (TCDCA) were significantly increased in patients with liver cirrhosis as compared with normal subjects. The cholic acid (CA) level and the ratio of the sum of free and conjugated CA to the sum of free and conjugated chenodeoxycholic acid (CDCA) were significantly elevated in patients with compensated as compared with decompensated liver cirrhosis, and were useful for differentiation of the two conditions. Serum bile acid levels were determined after oral administration of 500 mg of CDCA in the 5 normal subjects and 11 patients with liver disease. The TBA level reached a peak 90 min after CDCA administration in patients with chronic hepatitis and after 120 min in those with liver cirrhosis. The increase in the TBA level was significantly greater in patients with liver disease than in normal subjects. CDCA, GCDCA, and TCDCA showed changes similar to those in TBA. In patients with decompensated liver cirrhosis, the reduction in the TBA and CDCA levels after the peaks was slow, and GCDCA and TCDCA levels continued to increase until 180 min after the administration of CDCA. The TBA and CDCA levels 180 min after CDCA administration were significantly different among normal subjects, patients with chronic hepatitis, those with compensated liver cirrhosis, and those with decompensated liver cirrhosis, suggesting the usefulness of CDCA administration in differentiation of these conditions.

Diagnostic value of serum immunoreactive conjugated cholic or chenodeoxycholic acids in detecting hepatobiliary diseases. Comparison with levels of 3 alpha-hydroxy bile acids determined enzymatically and with routine liver tests

The diagnostic value of the enzymatic fluorometric method for total serum bile acids (TSBA) and for radioimmunoassay measurement for conjugated cholic acid (CCA) or chenodeoxycholic acid was compared with that of routine liver function tests in 223 patients with liver disease, 88 healthy subjects, and 118 patients affected by other diseases. The value of the tests for screening in the general population was assessed by simulation, using estimates of disease prevalence. TSBA was significantly more sensitive (78%) but less specific (94%) than CCA (sensitivity of 69%, specificity of 98%). Aspartate aminotransferase was nearly as sensitive (74%) as TSBA, but significantly less specific (93%) than CCA. CCA provided the highest positive predictivity (98%), even in a screening simulation (32%). With the use of sequential aspartate aminotransferase measurement followed by CCA, this value rose to 100%. This test procedure appears to be the best screening method for liver diseases available at present.

Evaluation of an oral bile acid loading test for assessment of liver function in chronic hepatitis. A comparison with fasting serum bile acids and i.v. galactose elimination test

In 40 patients with histologically verified chronic hepatitis, (chronic persistent hepatitis, n = 13; chronic active hepatitis without, n = 14; or with cirrhosis, n = 13), of viral and autoimmune origin, serum bile acids (SBA) were measured before and during 3 h after oral ingestion of 1 g chenodeoxycholic acid (CDA). Fasting SBA were elevated in 22 (55%) patients, whereas the CDA loading test was abnormal in 15 (38%) patients and the galactose elimination was prolonged in 16 (40%) patients. In patients with chronic active hepatitis, 20/27 had elevated SBA either in the fasting state (18/27) or after the CDA loading test (13/27). Normal SBA values were found in 9/13 (70%) patients with chronic persistent hepatitis. Thus, fasting SBA is not sensitive enough to detect mild chronic inflammatory liver disease as chronic persistent hepatitis, but seems to be as sensitive as the galactose elimination or CDA loading tests in detecting potential severe liver disease. Fasting SBA may thus be used as a complement of conventional liver tests in the follow-up of chronic hepatitis as assessment of liver function. An oral CDA loading and an i.v. galactose elimination test add no further information to that given by fasting serum bile acids.

Advances in the application of biochemical tests to diseases of the liver and biliary tract: their role in diagnosis, prognosis, and the elucidation of pathogenetic mechanisms

Despite the biochemical complexity of the liver, few laboratory tests provide discriminatory diagnostic information in patients with hepatobiliary disease. Recent efforts have concentrated upon tests which assess the function of the liver, the severity of the disease state, and underlying pathological processes. Bile Acids: The emergence of facile technology and widespread application has brought the realization that these assays are not as sensitive in detecting liver disease as previously believed, although the cholate/chenate ratio may be useful in distinguishing cholestasis from chronic liver disease. The presence of unusual bile acids in serum or urine may be helpful in some cases. Drug Metabolism: A number of tests provide good evidence about liver function, hepatic blood flow and portal shunting, but the aminopyrine breath tests is the most useful, giving prognostic information in acetaminophen overdose and alcoholic liver disease. The antipyrine half-life identifies surgical cases at risk from poor hepatic function. Proteins and Immunochemical Tests: Interest has developed in plasma proteins such as prealbumin and retinol-binding protein to monitor hepatic protein synthetic function. Secretory IgA is more elevated in biliary tract disease, unlike the native protein which is increased principally in cirrhosis. Type III procollagen can be measured in serum, and correlates with the activity of collagen synthesis and the degree of fibrosis in biopsy samples. Reye's Syndrome: Biochemical tests play an essential role in diagnosis of this recently discovered disease. These will be presented and discussed.

Diagnostic sensitivity of fasting and postprandial serum bile acids determined by different methods

The diagnostic sensitivities of serum bile acids determined by three different methods in the fasting and in the postprandial state were compared in 43 patients with cirrhosis of the liver. When a method with high analytical sensitivity (capillary gas-liquid chromatography, GLC, or radioimmunoassay, RIA) was used, the serum concentrations of bile acids exhibited similar diagnostic sensitivities in the fasting state (GLC, 98%; RIA, 93%) and in the postprandial state (GLC, 95%; RIA, 93%). By contrast, when an enzymatic method with limited analytical sensitivity was employed, the diagnostic sensitivity of fasting serum bile acids was lower (79%) than that of postprandial serum bile acids (93%). The measurement of individual serum bile acids by GLC did not add any further diagnostic information. The results of this study demonstrate that the diagnostic sensitivity of serum bile acids strongly depends on the analytical method used.