Secondary Hyperpahyroidism is seen in all of the following, Except

Answer is B (Parathyroid adenoma): Parathyroid Adenomas are associated with Primary Hyperparathyroidism and not Secondary Hyperparathyroidism. Hyperparathyroidism Primary Hyperparathyroidism Elevated PTH due to increased PTH secretion from an intrinsic abnormality of one or more parathyroid glands This is most commonly due to solitary adenoma involving one gland Causes Single adenoma (80-90%) Multiple adenoma (1-4%) Diffuse hyperplasia (3-15%) Carcinoma (1-2%) Secondary Hyperparathyroidism Excessive secretion of PTH by parathyroids secondary to a lowered serum ionized calcium This is a compensatory hyperplasia of all four glands aimed at correcting lowered serum calcium Causes Chronic renal failure Malabsorption syndrome Vitamin D deficiency Medullary carcinoma thyroid Medullary carcinoma of Thyroid is derived from parafbllicular cells of ultimobrachial organs and secretes calcitonin. Calcitonin is known to cause hypocalcemia which can lead to Secondary Hyperparathyroidism (Medullary carcinoma Thyroid in association with MEN II syndrome may also be associated with Primary Hyperparathyroidism from associated primary parathyroid Hyperplasia).