CALCA and medullary thyroid gland carcinoma: Furthermore, in the workup of secretory syndromes associated with neuroendocrine neoplasms, baseline assessment of plasma metanephrines, urinary 5-hydroxyindoleacetic acid (5-HIAA), and serum calcitonin is recommended as a minimum diagnostic evaluation [4]. In the present case, a comprehensive workup including these evaluations was performed, ultimately leading to the diagnosis of MTC.