Abstract
Since thyroglobulin has been detected in thyroid venous blood and lymph 1 , 2 but not in the general circulation, it would appear that the compound must be destroyed, or eliminated from the blood stream rather rapidly. At any rate the concentration of the protein does not become large enough to detect by the precipitin method. A study was undertaken to see how rapidly thyroglobulin could be eliminated when injected intravenously, and what the fate of the compound was.
Thyroglobulin was prepared from fresh hog thyroids by precipitating the protein in the isoelectric range. Antibodies were developed in rabbits by injecting this protein, and the antiserum was collected after 10 days. Suitable amounts of the hog thyroglobulin were injected intravenously into dogs. Samples of blood were withdrawn before and at various intervals after injection. Each sample of serum was diluted in a series of tubes and the antiserum added to each. The last tube showing a precipitin test was designated +, and those preceding were roughly gauged ++, +++, and ++++ by inspection.
Table I is a typical experiment.
It can be seen that thyroglobulin is steadily removed from the blood stream. Similar results have been obtained with 8 dogs. Smaller dogs remove the protein slower but the rate in terms of body weight has not yet been determined. The rate of elimination is apparently independent of the concentration in the blood. If the time necessary for 30 mg. of thyroglobulin to disappear is determined, it has been found that injection of 60 or 90 mg. requires about 2 or 3 times longer. One animal has been injected 13 times over a period of 18 days without any perceptible change in the rate of elimination.
Get full access to this article
View all access options for this article.