Objectives: Thyroid antibodies are present in more than 15% of patients with primary biliary cirrhosis. Inversely, the prevalence of antimitochondrial antibodies in patients with thyroid antibodies is still unknown. The aim of the present study was to evaluate the prevalence of antimitochondrial antibodies in women positive for thyroid microsomal antibodies.
Methods: Anti-thyroid microsomal positive sera were collected from 351 selected female patients (age range 40-70 years) then stored at -20 degrees C from September 91 to September 92. Anti-mitochondrial auto-antibodies were determined in all sera with enzyme-linked sorbent assay (ELISA) using purified antigen.
Results: M2 antimitochondrial antibodies were found positive in 7 cases (2%). On immunoblots, the pattern of antimitochondrial reactivity visualized for the 7 sera was similar to pattern of classical primary biliary cirrhosis sera. Six of the 7 patients were asymptomatic and 4 had normal liver function tests. Liver biopsy was carried out in 2 patients and fulfilled diagnosis criteria for primary biliary cirrhosis. Six out of the 7 patients had Hashimoto's thyroiditis (2 biopsy proven, 4 clinical and biological diagnosis).
Conclusion: Patients with Hashimoto's thyroiditis would be a population at high risk of primary biliary cirrhosis. It would be interesting to screen these patients in order to ascertain the signification of antimitochondrial antibody positivity, especially when there is no apparent liver disease.