Hepatobiliary diseases associated with serum antimitochondrial antibody (AMA)

Diagnostic value of anti-mitochondrial antibody in patients with primary biliary cholangitis: A systemic review and meta-analysis

BACKGROUND

Anti-mitochondrial antibodies (AMA) and the M2 subtype are considered serological hallmarks in the diagnosis of primary biliary cholangitis (PBC). However, these autoantibodies may be undetectable in some patients. This meta-analysis aimed to evaluate the diagnostic accuracy of serum AMA and M2 for PBC.

METHODS

We systematically searched PubMed, Embase, Web of Science, and the Cochrane Library for relevant studies. Pooled sensitivity, specificity, positive likelihood ratio (LR+), negative likelihood ratio (LR-), and diagnostic odds ratio (DOR) were calculated using a random-effects model. We also constructed hierarchical summary receiver operating characteristic curves and calculated the area under the curve values.

RESULTS

Our meta-analysis included 28 studies, of which 24 examined the diagnostic accuracy of AMA for PBC. Pooled sensitivity and specificity of AMA were 84% (95% confidence intervals [CI] 77-90%) and 98% (96-99%), respectively. Pooled LR+, LR-, and DOR were 42.2 (22.1-80.5), 0.16 (0.11-0.24), and 262 (114-601), respectively. Sixteen studies explored the diagnostic value of the M2 subtype, demonstrating pooled sensitivity and specificity of 89% (81-94%) and 96% (93-98%), respectively. Pooled LR+, LR-, and DOR were 20.3 (8.0-51.1), 0.12 (0.05-0.26), and 169 (41-706), respectively. The hierarchical summary receiver operating characteristic curves for both of serum AMA and M2 subtype lie closer to the upper left corner of the plot with area under the curve values of 0.98 (95% CI = 0.96-0.99) and 0.98 (95% CI = 0.96-0.99) respectively.

CONCLUSION

This meta-analysis provides evidence affirming the utility of AMA and M2 as sensitive and specific serological hallmarks that can facilitate early screening and diagnosis of PBC.

Is routine cholangiography useful in men with suspected primary biliary cirrhosis?

The aim of this study was to assess the diagnostic value of cholangiography in men with chronic cholestasis and positive antimitochondrial antibody (AMA) titers who were suspected of having primary biliary cirrhosis (PBC). The authors reviewed retrospectively the records of men who had positive AMA titers over a 16-month period to determine the results of cholangiography. They also reviewed the records of 102 patients with primary sclerosing cholangitis (PSC) from 1989 to 1995 who had undergone cholangiography and testing for AMA. Of 35 men with positive tests for serum AMA, 12 of these patients were referred for cholangiography (11 endoscopic and 1 transhepatic). All completed cholangiograms were normal. A diagnosis of PBC was made in nine patients and atypical autoimmune hepatitis in one. Conversely, only two PSC patients had positive AMA titers (1:20 and 1:80). Both of these patients had coexisting inflammatory bowel disease and cholangiograms diagnostic of PSC. Cholangiography was negative in the male patients with positive AMA titers who were suspected of having PBC. In men with cholestatic liver biochemistries and strongly positive AMA titers, especially in the absence of associated inflammatory bowel disease, routine cholangiography does not add to the diagnostic evaluation.

The predictive value of antimitochondrial antibodies in establishing the diagnosis of primary biliary cirrhosis

Primary biliary cirrhosis (PBC) was diagnosed in 85% of patients with antimitochondrial antibodies (AMA) found in sera routinely analyzed for autoantibodies. In these patients and in those without PBC other autoimmune disorders were common, but the latter patients generally had a low AMA titer, 1:80 or less. It was concluded that a low AMA titer may occur in many patients without PBC. On the other hand, it appears very likely that PBC is present in patients with an AMA titer exceeding 1:80 and an increased activity of alkaline phosphatases without signs of extrahepatic biliary obstruction.

Primary biliary cirrhosis in men

To determine whether primary biliary cirrhosis differed in men and women we reviewed the presenting features and clinical course of 39 men and 191 women with primary biliary cirrhosis followed at this unit between 1970 and 1984. Age and severity of disease at time of diagnosis were similar in both groups. Pruritus was significantly less common in men than in women both at diagnosis and throughout the period of follow up (p less than 0.01). The difference in incidence of pruritus at diagnosis was most evident when the male group were compared with a group of premenopausal women, an observation which is consistent with involvement of sex steroid metabolism in the origin of pruritus. Skin pigmentation was also less marked in men at diagnosis (p less than 0.05). Autoimmune associated conditions, especially sicca syndrome, were more common in women. Survival was similar among men and women although hepatoma developed significantly more frequently in male patients (p less than 0.01).

A choledochal cyst in association with primary biliary cirrhosis

A 62-year-old woman is described who was found to have both primary biliary cirrhosis and a large choledochal cyst. This association has not been previously reported. This case also illustrates the need for further investigation of the biliary tract in patients with primary biliary cirrhosis.

Antimitochondrial antibodies: reagent variables may lead to diagnostic error

Laboratory-prepared and commercially obtained fluorescein-labeled rabbit antihuman IgG were compared in performing the antimitochondria antibody (AMA) assay. Identical results were obtained using either of the fluorescent antisera at protein concentrations of 1.5 mg/ml and 1:10 dilutions of patients' sera. Positive AMA tests with either antisera were observed in each of 7 patients with primary biliary cirrhosis (PBC), 2 of 83 patients with miscellaneous hepatic diseases, and in 1 of 24 patients with extrahepatic biliary obstruction (EBO) of 2-24 weeks duration. However, when undiluted commercial fluorescent antiserum (15.8 mg protein/ml) was substituted in the assay, sera from 11 of 23 AMA-negative patients with EBO and 12 of 15 with miscellaneous liver diseases demonstrated an atypical fluorescence located primarily along the periphery of the rat renal tubules. Thus, if the conjugated antibody is not adjusted to an optimal protein concentration, this atypical fluorescence could be interpreted as a positive AMA test and lead to diagnostic error.

Primary biliary cirrhosis and coeliac disease: an association?

The association of primary biliary cirrhosis and coeliac disease, not previously reported, was observed in 4 patients. In each case, the two conditions were diagnosed simultaneously, and although symptoms were due to coeliac disease, initial investigation drew attention to the liver condition. All the patients responded to a gluten-free diet and remain well 2 years later. Primary biliary cirrhosis remains asymptomatic in 3 patients, but pruritus has developed in the 4th. The significance of this association is unclear and may merit formal study. Coeliac disease should be considered as a possible cause of unexplained weight loss in primary biliary cirrhosis.

Serum bile acids in alcoholic liver disease. Comparison with histological features of the disease

Fasting serum bile acids were measured by gas-liquid chromatography in 64 patients with alcoholic liver disease and compared with histological features in their percutaneous liver biopsy specimens. Total bile acid concentrations were normal (less than 2 mug/ml) or minimally increased in 6 patients in whom fatty infiltration was the only hepatic lesion. In the remaining 58 patients with more severe histological lesions, levels were increased in 93%, whereas serum bilirubins were elevated in only 43%. Chenodeoxycholic acid was usually the predominant serum bile acid, regardless of the degree of necrosis or connective tissue change in the biopsy specimen. Only small amounts of the secondary bile acids, deoxycholic acid and lithocholic acid, were detected. Levels of these secondary bile acids did not correlate with histological features.