• Claudia Ramos, Dagoberto Ojeda, David Cohn, and Nelson Wohllk.
• Sección Endocrinología, Hospital del Salvador, Facultad de Medicina, Universidad de Chile.
• Rev Med Chil. 2005 Sep 1; 133 (9): 1029-36.

BackgroundWith the availability of the RET proto-oncogene genetic testing, it is possible to perform prophylactic total thyroidectomy among carriers of RET mutation.AimTo evaluate the histological findings and the effects of the prophylactic total thyroidectomy in first-degree relatives of Chilean patients with multiple endocrine neoplasia type 2 (MEN 2) based on the Ret proto-oncogene analysis.Subjects And MethodsNineteen patients belonging to 11 MEN 2 families underwent total thyroidectomy. Of these, 16 either with C cell hyperplasia (CCH) or microscopic medullary thyroid carcinoma (MTC) were selected for the final analysis.ResultsThe age at the moment of thyroidectomy ranged from 3 to 24 years (median 9.5). The most common mutation was located in codon 634 (69%) followed by codon 620 (25%). Histopathology revealed MTC in 13 patients (81%, youngest 3 years, oldest ones 19 and 24 years) and CCH in 3. A significant correlation was observed between basal preoperative serum calcitonin/tumor size (r = 0.53, P < 0.05) and age/tumor size (r = 0.56, P < 0.03), but not between basal preoperative serum calcitonin and age. Stimulated preoperative calcitonin levels were confounding and not useful for differentiating CCH from MTC. None of patients in whom cervical dissection was done (9/16) presented lymph node metastases, including the oldest ones. All patients but the older ones were biochemically cured after a mean of 5 years of follow-up.ConclusionProphylactic total thyroidectomy should be done early in life because there is an age-dependent progression from HCC to MTC. MTC often precedes biochemical detection of the disease.

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