Endocrinology · NEET PG Preparation Medicine
A 45-year-old man is evaluated for recurrent kidney stones, bone pain, and generalized fatigue. Serum calcium is 11.8 mg/dL (normal 8.5-10.2), serum…
Practice question from Endocrinology (NEET PG Preparation Medicine), with the correct answer and a step-by-step solution.
medium · MCQ · Q-448255
A 45-year-old man is evaluated for recurrent kidney stones, bone pain, and generalized fatigue. Serum calcium is 11.8 mg/dL (normal 8.5-10.2), serum phosphate is 2.1 mg/dL (normal 2.5-4.5), and intact PTH is markedly elevated at 145 pg/mL (normal 10-65). 24-hour urinary calcium excretion is elevated. Which of the following is the most common cause of primary hyperparathyroidism?
- A.Parathyroid carcinoma
- B.Single parathyroid adenomaCorrect answer
- C.Four-gland parathyroid hyperplasia
- D.Ectopic PTH secretion by a neuroendocrine tumor
Solution
Primary hyperparathyroidism is most commonly caused by a single benign parathyroid adenoma (accounting for approximately 80-85% of cases). Four-gland hyperplasia accounts for 10-15% of cases, multiple adenomas for fewer than 5%, and parathyroid carcinoma is extremely rare (<1%).
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