Objectives: Thyroid antibodies are present in more than 15% of patient
s with primary biliary cirrhosis. Inversely, the prevalence of antimit
ochondrial antibodies in patients with thyroid antibodies is still unk
nown. The aim of the present study was to evaluate the prevalence of a
ntimitochondrial antibodies in women positive for thyroid microsomal a
ntibodies. Methods: Anti-thyroid microsomal positive sera were collect
ed from 351 selected female patients (age range 40-70 years) then stor
ed at -20 degrees C from September 91 to September 92. Anti-mitochondr
ial auto-antibodies were determined in all sera with enzyme-linked sor
bent assay (ELISA) using purified antigen. Results: M2 antimitochondri
al 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 o
f the 7 patients were asymptomatic and 4 had normal liver function tes
ts. 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 d
iagnosis). Conclusion: Patients with Hashimoto's thyroiditis would be
a population at high risk of primary biliary cirrhosis. It would be in
teresting to screen these patients in order to ascertain the significa
tion of antimitochondrial antibody positivity, especially when there i
s no apparent liver disease.