parathyroid disease
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Indications for parathyroidectomy in tertiary hyperparathyroidism include:
- Persistently elevated calcium (eg, >10.5 mg/dL), phosphorus, or PTH (eg, >800 pg/mL) levels
- Soft tissue calcification or calciphylaxis (vascular calcification with skin necrosis)
- Intractable bone pain or pruritus
Bisphosphonates are generally not recommended in end-stage renal disease as they reduce bone turnover, leading to osteomalacia, mixed uremic osteodystrophy, and adynamic bone disease. They can also cause a worsening of hyperparathyroidism.
Indications for primary hyperparathyroidism
The evaluation of hypercalcemia depends on parathyroid hormone (PTH) levels. Hypercalcemia with an elevated or inappropriately normal PTH (PTH-dependent) is caused by very few disorders, mainly primary hyperparathyroidism (PHPT). Parathyroid adenoma causes nearly 90% of PHPT. Other etiologies include parathyroid hyperplasia and carcinoma. Parathyroidectomy is indicated for patients with PHPT who have:
- Age <50 (and are therefore likely to develop eventual complications)
- Osteoporosis (T score <-2.5 at the hip, spine, or forearm)
- Serum calcium >1 mg/dL above the upper limit of normal
- Renal insufficiency (creatinine clearance <60 mL/min)
Less common causes of PTH-dependent hypercalcemia include familial hypocalciuric hypercalcemia (FHH), lithium-induced hypercalcemia, tertiary hyperparathyroidism (in renal failure patients), and ectopic PTH production by malignant tumors (rare). FHH is a rare autosomal dominant disorder caused by an abnormal calcium-sensing receptor on the parathyroid cells. FHH can be differentiated from PHPT by measuring urinary calcium excretion, which is markedly low in FHH but normal to high in PHPT.