Endocrine Abstracts

Introduction: MTC originates from the parafollicular calcitonin secreting cells. One quarter of MTC patients have familial form of the disease with RET mutation.

Case reports: First female patient underwent total thyroidectomy for MTC at the age 40. Further investigation showed elevated urinary catecholamine levels and MIBG scintiscan verified bilateral pheochromocytoma. Bilateral adrenalectomy was performed. On follow-up basal and stimulated calcitonin levels, serum levels of metanephrine, normetanephrine, and parathyroid hormone were normal. Since the mother of our patient had bilateral pheochromocytoma, genetic testing was done. It revealed RET 634 codon mutation in our patient, her 67 years old mother and her 12 years old daughter. Further examinations showed the mother of our patient had MTC and primary hyperparathyroidism, and she was operated on. Daughter of our first patient had elevated basal and stimulated calcitonin levels along with c634 RET mutation and total thyroidectomy was done. She had not developed hyperparathyroidism and pheochromocytoma up to now. Pathologic analysis proved multicentric MTC in all patients.

Our second female patient underwent total thyroidectomy at the age 57 on the grounds of non-functional nodules in the thyroid, with elevated calcitonin and CEA levels. Total parathyroidectomy with implantation of one parathyroid gland in sternocleidomastoid muscle was done, due to primary hyperparathyroidism. Histology proved MTC and hyperplastic parathyroids. She had a tumour in the left adrenal gland, with preserved adrenal function, and negative MIBG scintiscan and PET scan. On the control basal and stimulated calcitonin levels and CEA were in reference range. Slightly increased chromogranin A persists. Genetic testing did not find positive RET mutation.

Conclusion: Genetic screening for RET mutations is extremely helpful in finding familial forms of malignant tumours and reducing mortality in hereditary MTC, particularly since MTC in RET positive children is most commonly occult at the time of screening.