Summary
Fibrinolytic activity and factor VIII concentration were studied in 30 patients with
moderate to minimal hypothyroidism and in 7 patients with hyperthyroidism. In the
hypothyroid group, the results were related to serum thyroxine levels, HL-A phenotypes
and thyroid autoantibody titres. As serum thyroxine decreased so did factor VIII concentration,
however, euglobulin lysis time was correspondingly prolonged. Factor VIII appears
to be the most sensitive among coagulation factors to the deterioration of thyroid
function tests. There was a significant correlation between the reciprocal of thyroid
antibody titres and fibrinolysis; however, there was no relationship between factor
VIII concentration or fibrinolysis and a specific HL-A phenotype although the incidence
of HL-A8 was increased in the group as a whole.
Euglobulin lysis time was prolonged in 6 out of 7 patients with Graves’ hyperthyroidism.
Factor VIII was elevated in only 3 of these patients.