Treatment of thyroid-stimulating hormone-secreting adenomas with octreotide

Abstract

From data collected in the literature, the effects of octreotide therapy in 37 patients with thyroid-stimulating hormone (TSH)-secreting adenomas who received short-term (1 to 2 weeks, n = 23) and long-term treatment (3 to 36 months) are reviewed. In 20 of 21 patients studied, short-term administration of octreotide (50 or 100 μg subcutaneously [SC] produced a 25% to 100% (mean ± SD, 55.3% ± 29%) decrease in TSH levels, with the nadir being obtained between the third and sixth hour following injection. After 1 to 2 weeks therapy with 50 to 100 μg twice or three times a day, 21 of 23 patients studied demonstrated a 66% (±30%) decrease in TSH levels and 14 of 16 showed a 64% (±27%) decrease in α-subunit levels. In approximately two thirds of the patients, the response was better than after short-term administration. The effect of octreotide on clinical and biological thyroid status was significant in all patients studied. After 1 week or 1 month of treatment, thyroid hormone levels were reduced in all patients and were normalized in 78%. Response to therapy was similar whether TSH secretion was pure or mixed (growth hormone [GH]-TSH adenomas). Fourteen patients received long-term treatment (3 to 36 months; mean, 12 ± 10) with daily doses ranging from 200 to 1,500 μg. The response was better than or similar to that with short-term treatment. An escape occurred in TSH levels in two patients and in thyroid hormone levels in three patients, leading to an adjustment of dose or frequency of injection. A partial shrinkage of the adenoma was demonstrated by a computerized tomography (CT) scan and/or magnetic resonance imaging (MRI) in six patients, with a 30% to 50% reduction occurring in three of these patients. In conclusion, octreotide may currently be considered the treatment of choice in TSH-secreting adenomas when surgery and/or radiotherapy have been unsuccessful. Octreotide reduced TSH secretion in almost all the patients, leading to normalization of thyroid hormone levels in three quarters; partial tumor shrinkage was observed in one third of the patients on long-term treatment.