ALTERED THYROID STATES AND RADIOGALLIUM DISPOSITION IN THE BALB/C MOUSE
Abstract
The objective of this research was to determine the effect of experimentally altered thyroid states on the tissue distribution and whole body retention of gallium-67 citrate in mice and to correlate the effects with serum total iron binding capacity or related parameters. A 21-day drug pretreatment was used to obtain the desired thyroid state. A T-4 radioimmunoassay was used to determine total serum thyroxine levels to verify the attainment of the altered thyroid state. An iron-59 kit was used for the radiometric determination of serum total iron binding capacity, serum unsaturated iron binding capacity, and serum iron concentration for hypo-, euu-, and hyperthyroid animals. In the whole body retention study each of three treatment groups consisted of six animals. All animals received gallium-67 intravenously. Whole body radioactivity measurements were made between 2 and 96 hr post-injection. In the tissue distribution study each of three treatment groups consisted of 24 animals. At 6, 12, 24, and 48 hr after gallium administration, six animals from each treatment group were sacrificed by decapitation. Major organs and an aliquot of blood were removed from each animal and assayed for gallium radioactivity. Significant treatment effects were observed in the tissue distribution and whole body studies. In both experiments, hyperthyroidism resulted in the reduction of gallium activity at various time intervals after gallium-67 administration. Although hyperthyroidism did not have a significant effect upon total iron binding capacity, serum iron values were significantly increased. Hypothyroidism caused a significant decrease in total iron binding capacity which may be equated with a decrease in serum transferrin. No significant change in radiogallium disposition was observed, however. The relatively rapid loss of gallium activity from the whole body and tissues exhibited by the hyperthyroid group is consistent with recent reports that suggest that an inverse relationship exists between serum iron levels in the blood and target to non-target ratios of gallium activity. The results of these experiments support the hypothesis that the iron status of a patient may play an important role in scintigraphic studies utilizing gallium-67 citrate.
Degree
Ph.D.
Subject Area
Pharmaceuticals
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.