Question
A 65-year-old man comes to the physician because of fatigue and muscle cramps for the past 4 weeks. He has also noticed several episodes of tingling in both hands. He has not had fever or nausea. He has had a chronic cough for 10 years. He has chronic bronchitis, hypertension, and osteoarthritis of both knees. His father died from lung cancer. Current medications include salbutamol, ibuprofen, and ramipril. He has smoked 1 pack of cigarettes daily for 45 years. He is 175 cm (5 ft 9 in) tall and weighs 68 kg (163 lb); BMI is 22 kg/m2. His temperature is 36.7°C (98°F), pulse is 60/min, and blood pressure is 115/76 mm Hg. While measuring the patient’s blood pressure, the physician observes carpopedal spasm. Cardiopulmonary examination shows no abnormalities. His hematocrit is 41%, leukocyte count is 5,800/mm3, and platelet count is 195,000/mm3. Serum alkaline phosphatase activity is 55 U/L. An ECG shows sinus rhythm with a prolonged QT interval. Which of the following is the most likely underlying cause of this patient’s symptoms?
| A. |
Multiple Endocrine Neoplasia |
| B. |
Ectopic hormone production |
| C. |
Destruction of parathyroid glands |
| D. |
Albright hereditary osteodystrophy |
Show Answer
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Correct Answer � C Explanation |
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Answer:C. Destruction of parathyroid glands
This patient presents with hypocalcemia, which is often caused by hypoparathyroidism. The most common cause of hypoparathyroidism is surgical destruction of parathyroid glands (e.g., thyroidectomy, parathyroidectomy). Since this patient does not have a history of surgery, he most likely has hypoparathyroidism due to autoimmune destruction of parathyroid glands, which is the second most common cause of hypoparathyroidism in adults. Hypoparathyroidism also manifests with hyperphosphatemia and normal levels of ALP.