Summary
Twenty-one thyroprival patients, previously submitted to total thyroidectomy for tumours,
were investigated during stabilized L-thyroxine supplementation and at the end of
a 20-25 day “no-therapy” period, necessary for a 131I total body scintigraphy. During supplementation therapy a lower than normal mean
betathromboglobulin (beta-TG) release level was found, the other blood clotting and
platelet function tests being normal. After substitution therapy withdrawal, platelet
function tests showed reduced adrenalin aggregation, increased collagen threshold
aggregating concentrations, decreased beta-TG release values and reduced aggregation
to ristocetin, whereas blood clotting tests showed prolonged aPTT values and reduced
levels of factor VIII: C and vWf: Ag. We conclude that in acquired hypothyroidism
the lowering of factor VIII: C and vWf: Ag (acquired von Wille brand disease) is associated
with impaired platelet reactivity not only to ristocetin but also to collagen and
especially adrenalin. In the patients investigated these changes were almost completely
corrected by substitutive therapy with L-thyroxine at clinically effective doses.
Keywords
Acquired hypothyroidism - L-thyroxine treatment - Factor VIII - Platelet function
- Adrenalin aggregation
