Abstract
The pathophysiology of serum protein is not clearly understood, although various kinds of serum protein have been investigated in various diseases. It is considered that the cellular and the humoral immunities play important roles in the pathogenesis of hyperthyroidism and chronic thyroiditis. The purpose of this study is to clarify an aspect of the pathophysiology of hyperthyroidism, measuring the concentration of various kinds of serum protein in patients with hyperthyroidism.
The concentration of various kinds of serum protein, such as prealbumin (Pre), albumin (Alb), α1 acidglycoprotein (α1 AG), α1 antitrypsin (α1 AT), α2 HS glycoprotein (α2 HS), ceruloplasmin (Cp), haptoglobin (Hp), α2 macroglobulin (α2 Mc), βIC/A globulin (C3), βIE globulin (C4), C3 proactivator (C3PA), IgG, IgA and IgM was estimated by the single radial immunodiffusion method (SRID) in 25 cases of normal subjects (14 cases of male and 11 cases of female), 24 cases of untreated hyperthyroidism (5 cases of male and 19 cases of female) and a patient with malignant exophthalmus. C3PA and C3 activator (C3A) were assayed by Laurell's electroimmunoassay method in 14 cases of normal subjects and 15 cases of untreated hyperthyroidism.
The results obtained were the following :
1. The mean values of the concentration of Pre and Tf were significantly lower (P<0.05), and those of Alb, C4 and C3PA (SRID) showed a tendency to be lower in hyperthyroidism than in normal subjects. The mean values of the concentration of α1AT, Cp, C3 and IgG were significantly higher in the former than in the latter (P<0.05).
2. The relationship between the concentration of various kinds of serum protein and some parameters representing thyroid functions (BMR, T3RU, T4, cholesterol and free thyroxine index) was examined in hyperthyroid patients. Pre and Alb were negatively correlated with T3RU, and α1 AT and Cp were positively correlated with T3RU, T4 and free thyroxine index. However C3 and IgG did not correlate with such parameters.
3. The variations in the level of various serum protein after the administration of antithyroid drugs were observed in 12 cases of untreated hyperthyroidism. The serum levels of Alb and Tf showed a tendency to gradually increase, and those of α1AT, α2HS and Cp showed a tendency to gradually decrease. There was no definite change in the con-centration of the other serum proteins.
These results suggest that the decreased serum levels of Pre and Alb and the increased serum levels of α1AT and Cp in hyperthyroidism are closely related to the elevated blood levels of thyroid hormones in this disease. Decreased serum level of Tf in hyperthyroidism may be concerned with hypochromic anemia, which was frequently observed in this disease, and with the acceleration of the protein catabolism by thyroid hormones. The elevated serum levels of IgG and C3 are considered to have resulted from some factors which are dependent not on thyroid hormones but probably on immunological mechanisms.
