A 35-year-old woman is evaluated because of episodes of severe headaches, tremulousness, palpitations, and anxiety. The patient also has noted a change in her voice and difficulty swallowing solids. Blood pressure is 160/110 mm Hg, and pulse is 150 min. Physical examination shows a palpable, nontender swelling in the front of her neck that moves with deglutition. Nontender cervical lymphadenopathy is noted on both sides of the neck. Magnetic resonance imaging (MRI) of the abdomen discloses a mass in the right adrenal medulla. Laboratory studies show hypercalcemia. Which of the following serum studies is the most appropriate next step in diagnosis?
A. Antithyroglobulin antibodies
B. Calcitonin concentration
C. Parathyroid hormone (PTH) concentration
D. Thyroid-stimulating hormone (TSH) concentration
E. Thyroxine (T4) concentration
The patient has multiple endocrine neoplasia (MEN) syndrome type 2a. It is an autosomal dominant disease with a triad of hyperparathyroidism (hypercalcemia, hypertension), pheochromocytoma (increased catecholamines, hypertension), and medullary carcinoma of the thyroid. The thyroid mass in this patient is medullary carcinoma, which derives from C cells. C cells synthesize calcitonin. Only 10% of cases of medullary carcinoma are familial (90% are sporadic). Serum calcitonin is the best tumor marker for the cancer. Calcitonin is converted into amyloid within the thyroid gland. Patients with the familial variant have a 50% five-year survival rate. This patient has metastasis to the cervical lymph nodes, so the prognosis is likely to be worse.
A) Serum antithyroglobulin antibodies are increased in Hashimoto thyroiditis. The patient does not have any signs of hypothyroidism (e.g., muscle weakness, periorbital puffiness).
C) The patient has primary hyperparathyroidism, which is most often due to a parathyroid adenoma. The serum PTH is increased in hyperparathyroidism. However, the parathyroid adenoma is not responsible for the thyroid mass, because they generally are nonpalpable and do not metastasize to cervical lymph nodes. Therefore, a serum PTH is not helpful in defining the cause of the thyroid mass.
D) The serum TSH would be normal in this patient, because there are no signs of either hypothyroidism or hyperthyroidism. Serum TSH is not altered by thyroid cancer.
E) The serum T4 would be normal in this patient, because there are no signs of either hypothyroidism or hyperthyroidism. Serum T4 is not altered by thyroid cancer.
Fantastic explanations which make it easier to comprehend. Thx
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