We evaluated the concentration of epidermal growth factor (EGF) in pla
telets, serum and plasma obtained from 47 patients with Graves' diseas
e, 7 with hypothyroidism and 20 healthy subjects. The platelets of the
subjects were collected from platelet rich plasma and lysed by freezi
ng and thawing. Subsequently the platelet debris was treated with Trit
on X-100. The EGF concentration was determined by homologous radioimmu
noassay. The concentration of EGF in the platelets in 14 patients with
untreated Graves' disease was significantly higher than that in the h
ealthy controls. After treating these 14 patients with antithyroid age
nts, the EGF concentration in the platelets decreased to the level of
the healthy controls. The EGF concentration in the platelets in the 7
untreated hypothyroid patients decreased after replacement therapy wit
h thyroxine. The mean volume of the platelets in the 14 patients with
unheated Graves' disease was significantly larger than in the control
and decreased after treatment with antithyroid agents. The serum and p
lasma levels of EGF in the 7 untreated hypothyroid increased after rep
lacement therapy. In conclusion, thyroid function affected the concent
ration of EGF in the platelets of patients with thyroid disorders.