Thyroid and Parathyroid Conditions: Parathyroid Conditions.

Parathyroid hormone (PTH) helps regulate calcium homeostasis in a complex relationship with the gastrointestinal tract, kidneys, bone, and parathyroid glands. Abnormalities in PTH production can result in many conditions, including hypoparathyroidism, and primary, secondary, and tertiary hyperparathyroidism. Management of each abnormality centers on maintaining normal or near-normal serum calcium values to prevent complications. Most cases of hypoparathyroidism are caused by neck surgery and may result in acute hypocalcemia. Patients with chronic hypoparathyroidism are treated with a combination of calcium, vitamin D analogs, and, occasionally, exogenous PTH. A single parathyroid adenoma causes most cases of primary hyperparathyroidism, with multiglandular disease and cancer as other possible etiologies. All patients with symptomatic primary hyperparathyroidism and many with asymptomatic hyperparathyroidism undergo partial or full parathyroidectomy to correct the underlying condition. Chronic kidney disease-mineral and bone disorder (CKD-MBD) is the most common cause of secondary and tertiary hyperparathyroidism, in which hypocalcemia stimulates PTH production. Most patients with CKD-MBD are treated medically with phosphate binders, vitamin D analogs, and calcimimetics, but rare cases are managed with parathyroidectomy. Severe calcium or vitamin D deficiency also causes secondary hyperparathyroidism and is managed with calcium and vitamin D replacement.