prevention and treatment of secondary hyperparathyroidism
- • Dietary phosphate restriction (800–1000 mg/day). Avoid colas.
- • Calcium-based phosphate binders (calcium carbonate or calcium acetate limited to <1.5 g/day) or a noncalcium-based phosphate-binding resin (sevelamer, lanthanum) before meals if dietary restriction alone is unable to maintain serum phosphorous between 3.5 and 5.5 mg/dL (if on dialysis). If corrected total calcium is >9.5 mg/dL or vascular calcifications are present, a noncalcium-based phosphate-binding resin is preferred.
- • Vitamin D derivatives (paricalcitol, doxercalciferol, calcitriol, others): if corrected total calcium is <9.5 mg/dL and PTH levels are still >300 pg/mL. There is a need to monitor for hypercalcemia causing a high calcium–phosphate product, which ideally should be <55 to prevent vascular calcifications.
- • Calcimimetics (cinacalcet): if vitamin D derivatives are ineffective, corrected total calcium >8.4 mg/dL, and PTH >300 pg/mL. Use before vitamin D derivatives, if calcium–phosphate product above 55.
- • Once hyperparathyroidism has advanced, it may be refractory to these interventions, at which time subtotal parathyroidectomy is indicated to correct symptomatic hyperparathyroidism. Subtotal parathyroidectomy is also indicated in patients who develop tertiary hyperparathyroidism, which have symptoms such as high PTH levels (>800 pg/mL) and hypercalcemia in spite of being off all calcium and vitamin D therapies.