[Response of thyroglobulin, anti-thyroglobulin antibodies, TSH, FT4 and total T3 after rhTSH stimulation in differentiated thyroid carcinoma]

To analyse the behaviour of serum thyroglobulin (Tg), antithyroglobulin antibodies (TgAb), thyrotropin (TSH), free thyroxine (FT4) and total triiodothyronine (TT3) levels at each time during the rhTSH stimulation protocol in patients with differentiated thyroid carcinoma (DTC).

We carried out 117 rhTSH stimulations in DTC patients. We determined the serum levels of Tg, TgAb, TSH, FT4 and TT3 at baseline and 24, 48 and 96 hours after beginning stimulation, using RIA or IRMA. The software program SPSS 15.0 was used for statistical analysis of data.

We found statistically significant differences between the mean Tg values at different times (2.08 ng/ml baseline; 2.64 ng/ml at 24 hours; 4.98 ng/ml at 48 hours; 6.59 ng/ml at 96 hours), reaching maximum values at 96 hours. During this time, we observed the highest percentage of pathological values. After administration of rhTSH, there was a significant increase in the mean TSH value (98.88 mIU/l at 24 hours; 111.10 mIU/l at 48 hours). The mean TSH value at 96 hours decreased approximately 5 times with respect to the mean 48 hour value. We did not observe changes in the TgAb, FT4 or TT3 levels.

The assessment of Tg after rhTSH stimulation should be performed 96 hours after beginning stimulation. Administration of rhTSH causes a significant elevation in serum TSH levels, without modifying serum TgAb, FT4 or TT3 levels.