Recombinant human thyrotropin in radioiodine diagnostics and radioiodine ablation of patients with well-differentiated thyroid cancer: the first experience in Russia

Background. Traditional endogenous stimulation of thyroid-stimulating hormone (TSH) by means of long-term withdrawal of thyroid hormones for radioiodine diagnostics and radioiodine therapy causes severe hypothyroidism, which worsens patients’ general well-being and may lead to side effects and cause tumor growth and dissemination. Exogenous stimulation with recombinant human TSH (rh-TSH, thyrotropin-alfa) causes short-term increases in TSH levels and does not have the above-mentioned side effects. Purpose. To estimate the efficacy and safety of rh-TSH in preparation of patients with well-differentiated thyroid cancer for radioiodine diagnostics and radioiodine therapy. Methods. We conducted an interventional single-center prospective unblinded uncontrolled study of the efficacy and safety of thyrotropin-alfa to prepare patients with well-differentiated thyroid cancer to radioiodine diagnostics and post-surgery radioiodine ablation. The study included 88 patients with well-differentiated thyroid cancer: 54 patients were prepared for post-surgery radioiodine ablation; 34 patients – for radioiodine diagnostics to evaluate combined treatment efficacy and exclusion of tumor recurrence. The level of TSH, thyroglobulin, antibodies to thyroglobulin, whole body scintigraphy, and side effects were measured during exogenous stimulation with thyrotropin-alfa. Results. The level of TSH reached or exceed the target level (30 mIU/ml) 24 hours after the first injection of recombinant thyrotropin-alfa in 86% of patients; after 48 hours in 100%, the level exceeding 100 IU/ml was observed in 66 (75.1%) patients. The maximum levels of thyroglobulin and antibodies to thyroglobulin were reached 72 and 48 hours after the first injection, respectively. The injections of thyrotropin-alfa were well-tolerated by the patients. In the group for radioiodine diagnostics 2 (5.8%) patients complained of fatigue, 1 (2.9%) patient had signs of dyspeptic disorder, while in the group for radioiodine ablation 4 (7.4%) patients complained of fatigue, 1 (1.8%) patient had marked memory problems that disappeared later (they must have been caused by the patient’s advanced age (82 years)). Conclusions. Exogenous recombinant human thyroid-stimulating hormone (thyrotropin-alpha) is highly effective in preparation of patients with well-differentiated thyroid cancer for radioiodine diagnostics and radioiodine ablation. It does not have side effects, which are typical of withdrawal of thyroid hormones. The levels of thyroglobulin and antibodies to thyroglobulin measured 72 hours after the first injection of thyrotropin-alfa have the biggest diagnostic informative value.