Primary hyperparathyroidism due to PTH-secreting parathyroid adenoma is one of the most common causes of hypercalcemia. Elevated serum PTH increases absorption of calcium from gut, reabsorption of calcium from renal tubules, and mobilizes calcium from bones (causing osteoporosis); hypercalciuria increases the risk for renal stones. Presenting features of hypercalcemia include increased thirst, polyuria, lethargy, nausea, constipation, low mood, and nonspecific abdominal and bone aches. Diagnosis is made by elevated serum calcium and serum parathyroid hormone levels, often with low serum phosphate and normal renal function; neck imaging (ultrasonography, CT scan, and sestamibi scintigraphy) can localize the parathyroid adenoma. In patients with acute hypercalcemia, treatment includes intravenous fluids and bisphosphonates. The definitive treatment is parathyroidectomy of the overgrown parathyroid gland or glands. For patients who are not candidates for surgery (e.g. due to comorbidities), cinacalcet can be used long-term. Primary hyperparathyroidism can be part of familial multiple endocrine neoplasia syndromes MEN1 or MEN2. Less than 1% of primary hyperparathyroidism cases are due to parathyroid carcinoma.
See Hypercalcemia in The Manuals for more details.
References
Jameson JL, De Groot LJ (eds): Endocrinology: Adult and Pediatric (pt 6), chapter 63. Philadelphia, Saunders/Elsevier, 2015, pp. 1105-1125.
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