RET germline mutation testing has replaced biochemical screening with calcitonin to identify mutation carriers in MEN 2 families because calcitonin levels lack sensitivity and specificity, normal basal or stimulated calcitonin levels cannot exclude or predict development of MTC, pathological calcitonin levels cannot differentiate between chief cell hyperplasia and MTC, and stimulated calcitonin studies can occasionally produce false-positive results. Screening for pheochromocytoma and HPT is indicated in all variants of MEN 2 syndrome as some kindreds with MEN 2A syndrome manifest only MTC and thus incorrectly designated as FMTC. The presence of a functioning pheochromocytoma should always be excluded by appropriate biochemical screening before thyroidecto-my in any patient with MEN 2. Annual screening for pheochromocytoma with 24-hr urinary levels of catecho-lamines and catecholamine metabolites should continue until age 35 in all phenotypical variants of MEN 2 syndrome. Because pheochromocytomas in MEN 2 syndrome are often multiple and extra-adrenal, MIBG (131I-meta-iodobenzylguanidine) scintigraphy and MRI are needed for localization, only if the biochemical results are abnormal. Annual biochemical screening for HPT with serum parathyroid hormone (PTH) and ionized calcium is recommended for those patients who have not had parathyroidectomy and autotransplantation.
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The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.