Serum amino-terminal propeptide of type III procollagen in patients with hyperthyroidism or hypothyroidism during therapy.

Changes in serum amino-terminal type III procollagen propeptide (PIIIPN) and hydroxyproline were compared with indices of thyroid function in 33 patients with hyperthyroidism and 16 patients with hypothyroidism before and after treatment. Control values were obtained from 26 healthy individuals. Hyperthyroidism was shown to be associated with an increased level of PIIIPN and hypothyroidism with a decreased PIIIPN level. An increase in PIIIPN was found in 100% of hyperthyroid patients and a decrease in 31% of those with hypothyroidism, while hydroxyproline increased in only 54% of patients with hyperthyroidism and its level was decreased in only 6% of patients with hypothyroidism. Correlation between PIIIPN and thyroxine and triiodothyronine levels was shown. The results obtained suggest that PIIIPN is a valuable index of tissue response to thyroid hormones.