parathyroid disease

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.