Increased concentrations of type IV (7 S) collagen in sera of hyperthyroid patients with Graves disease.

Serum concentrations of type IV collagen (7 S) were determined in 29 patients with untreated hyperthyroidism and 30 healthy subjects. Serum 7 S collagen was significantly higher (P less than 0.0001) in the hyperthyroid patients (6.3, SD 1.3, micrograms/L) than in the healthy control subjects (3.9, SD 0.6, micrograms/L). No difference in serum concentrations of 7 S collagen were observed between patients with normal liver function and those with abnormal liver function. Serum concentrations of 7 S collagen correlated positively with serum concentrations of free triiodothyronine (r = 0.41, P less than 0.05). In the hyperthyroid patients, 7 S collagen concentrations in serum gradually fell into the normal range as thyroid function became normalized. Thus, hyperthyroidism is one of the diseases in which serum concentrations of 7 S collagen are increased.