Endocrine Abstracts

Background: Differentiated thyroid cancer (DTC) is the most common endocrine malignancy. Standard treatment includes thyroidectomy (extention depending on tumour size, pathology and lymph nodes involvement). If indicated, radioiodine therapy after TSH stimulation either by levothyroxine withdrawal or rhTSH administration is recommended. In patients with thyrotropin deficiency rhTSH administration is mandatory.

Case report: A 30-year-old woman, resident in an iodine deficient area, diagnosed with acromegaly (nadir GH in OGTT=34.9 ng/mL, increased IGF1=926 ng/mL), pituitary insufficiency and DTC is presented. She underwent treatment with dopamine agonists for a long period, transsphenoidal surgery in 2008, at 52-years-old, pituitary high voltage radiotherapy (2009) and somatostatin analogue (SSA) therapy, developing pituitary gonadotropin and thyrotropin insufficiency. Thereafter, the patient was diagnosed with toxic multinodular goiter and underwent thyroid surgery. The pathology exam revealed multiple follicular variant of papillary thyroid microcarcinoma. Due to long standing uncontrolled acromegaly, radioiodine therapy was recommended after administration of rhTSH. 100 mCi 131I was administered; stimulated thyroglobulin was increased and the scintigraphy revealed an increased uptake in her right pulmonary field. After 6 months, another 100 mCi 131I dose was administered. At last assessment acromegaly was controlled on Lanreotide therapy (mean random GH/24 hours=0.29 ng/mL and normal IGF1=135.3 ng/mL) and thyroglobulin was <0.1 ng/mL, anti-TGL antibodies were negative and there is no uptake on whole body scintigraphy.

Conclusion: In acromegalic patients submitted to radiotherapy and on SSA therapy, thyrotropin deficiency should be checked before radioiodine treatment for associated thyroid carcinoma. If present, rhTSH administration is mandatory and the outcome of patient is favorable.