During a routine checkup, a 45-year-old executive is found to have hypercalcemia. Subsequent workup reveals elevated parathormone, decreased phosphorus, elevated chloride, and normal blood urea nitrogen (BUN), and creatinine in serum. Urinary calcium is above normal levels. What is the most likely etiology?
- multiple myeloma
- primary hyperparathyroidism
- hypervitaminosis D
- sarcoidosis
- milk alkali syndrome
Answer(s): B
Explanation:
Primary hyperparathyroidism is characterized by hypercalcemia, hypophosphatemia, hyperchloremia, increased urinary calcium excretion, and an increase in serum parathormone level. Multiple myeloma is associated with hypercalcemia when there are many lytic lesions. Chronic ingestion of 50100 times the normal requirement of vitamin D is required to produce hypercalcemia in normal people, so hypervitaminosis D is rare and parathormone levels would be suppressed. With milk alkali syndrome, which is caused by excess ingestion of calcium and absorbable antacids, parathormone levels would also be suppressed. In sarcoidosis, about 10% of patients have hypercalcemia attributable to increased intestinal absorption of calcium and increased production of 1,25(OH)2D.
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