Background/Objective: Limited animal and human studies have shown function, albeit inadequate, 
of implanted thyroid tissue in muscles. This work aimed to ascertain results in a larger number of 
patients, finding practical method for implantation, studying the effect of changing weight of implant 
and effect of passage of time on its function. Methods: Forty patients had total thyroidectomy for 
simple multinodular goiters. A piece of the excised gland was finely minced, mixed with saline as 
emulsion, and injected in thigh muscles. Twelve patients had 5-g implants, while 28 patients had 10-g 
implants. Four parameters were studied at 2 months, 6 months, and 12 months: technetium isotope 
uptake by the implant; thyroid stimulating hormone (TSH); free T3 (FT3); and free T4 (FT4). 
Results: All autotransplanted thyroid tissue survived and functioned. After 12 months, mean values (_ 
standard deviation) of isotope uptake, TSH, FT3, and FT4 of the 5-g implants were 0.44 _ 0.16%, 
27.74 _ 30.4 UI/mL, 3.07 _ 1.10 pg/mL, and 1.01_0.3 ng/dL, respectively. Those for the 10 g 
implants were 0.71_0.20%, 22.78_19.7 UI/mL, 3.92_1.2 pg/mL, and 1.05 _ 0.3 ng/dL, respectively. 
Ten-gram implants showed significantly higher isotope uptake than 5-g. TSH, FT3, and FT4 
significantly improved over the period of 1 year. Conclusion: Injection of thyroid tissue suspension is 
a simple method for thyroid autotransplantation. TSH was elevated in the majority to maintain normal 
or near normal thyroid hormones. Ten-gram implants showed higher isotope uptake than 5-g, 
although this difference was not reflected by thyroid hormone profile. The implant seemed to function 
better with the passage of time from 2 months to 12 months.