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.

Links to this note

• Nephrology
  • parathyroid disease
• Parathyroid
  • parathyroid disease