Hypothyroidism and anti-endothelial cell antibodies.

Because of our previous demonstration of anti-endothelial cell antibodies (AECA) in patients with insulin-dependent diabetes mellitus and their association, in this condition, with thyroid disease, we sought these antibodies in patients with suspected thyroid dysfunction using an enzyme immunoassay with human umbilical vein endothelial cells as the substrate. AECA were found in 5/120 (4.2%) patients with normal and 15/97 (15.4%) with abnormal thyroid function. The increased prevalence in the latter group was due to a highly significant association between the presence of AECA and raised levels of TSH. We conclude that a highly significant correlation exists between the levels of AECA and TSH, but not between those of AECA and fT4. Patients with hypothyroidism as defined by high levels of TSH have AECA significantly more often than patients with low or normal TSH (22.2% versus 2.8% and 5.8%).