Effect of Plasmapheresis on Thyroid Hormone Section

The effect of plasmapheresis on thyroid hormone secretion was studied in the dog. Approximately 10% of body weight volume of blood was exchanged with red blood cells suspended in dextran solution over a period of 10-30 min. A striking increase in thyroid hormone release was observed within 2 hr. Addition of thyroid hormone to the blood cell suspension, however, did not prevent this response. Although the increase in thyroid hormone release was not universally seen in hypophysectomized dogs, in decerebrate dogs and in some hypophysectomized dogs a moderate response was observed. These results suggested the possibility that some mechanism other than pituitary-thyroid feedback might be involved. Since no marked change was observed local perfusion of the thyroid with blood cell suspension, extrathyroidal humoral factors were probably involved in this response. (Endocrinology 86: 1281, 1970)