Functional capacity of the thyroid autograft: an experimental study

BACKGROUND: The aim of this study was to investigate the functional capacity of thyroid autografts after total thyroidectomy in a rabbit model. MATERIAL AND METHODS: Thirty-eight rabbits underwent total thyroidetomy. One of the two thyroid lobes was cut into 1-mm pieces and was introduced intramuscularly into the right quadriceps muscle (group A, n = 10), the right rectus abdominalis muscle (group B, n = 10), and the right sacrodorsalis muscle (group C, n = 10). Another group of 8 rabbits underwent total thyroidectomy without autologous implantation and served as the control group (group D). The animals were observed for 8 weeks with weekly measurements of thyroid hormones. At the end of the 8th week, a scintigram was performed. The autografts were removed 2 days later. RESULTS: The thyroid hormone levels showed a gradual decrease until the 2nd-5th week after implantation, followed by a gradual increase and establishment of euthyroid levels between the 5th and 8th weeks. Respectively, an increase of thyreotropin hormone was noted with maximal values in the 4th week, followed by a gradual decrease until the end of the 8th week. The scintigram at the end of the 8th week revealed the presence of functional thyroid tissue in all cases. Functional thyroid follicles were found in all animals who survived. In 35.7% of the autografts, we noted the development of fibrous tissue and gigantocytic granulomas in the periphery, which could be interpretated as a "foreign body" reaction. CONCLUSION: Thyroid autografts can completely substitute thyroid function after total thyroidectomy.