Medical Care: Treatment depends on the severity of symptoms and the underlying cause.
" Volume expansion and saline diuresis
o Volume depletion results from uncontrolled symptoms leading to decreased intake and enhanced renal sodium loss. This tends to exacerbate or perpetuate the hypercalcemia by increasing Na+ reabsorption in the thick ascending limb of the loop of Henle (TALH). Thus, appropriate volume repletion with isotonic sodium chloride solution is an effective short-term treatment for hypercalcemia.
o Once volume is restored, simultaneous administration of loop diuretics blocks Na+ and calcium reabsorption in the TALH.
o Replacing ongoing sodium, potassium, chloride, and magnesium losses is important if prolonged sodium chloride and loop diuretic therapy is contemplated.
" Mobilization
o Immobilization aggravates hypercalcemia.
o Whenever possible, weightbearing mobilization should be encouraged.
" Reduction of gastrointestinal calcium absorption
o Reduction of dietary calcium and vitamin D intake is effective for treating hypercalcemia due to increased intestinal calcium absorption (eg, in idiopathic infantile hypercalcemia, ie, Williams syndrome).
o In vitamin D toxicity or extrarenal synthesis of 1,25(OH) D3 (eg, in sarcoidosis), prednisone may help reduce plasma calcium levels by reducing intestinal calcium absorption.
o Oral phosphate also can be used to form insoluble calcium phosphate in the gut.
" Inhibition of bone resorption
o Bisphosphonates inhibit osteoclastic bone resorption and are effective in the treatment of hypercalcemia due to conditions causing increased bone resorption and malignancy-related hypercalcemia.
o Pamidronate and etidronate can be given intravenously, while risedronate and alendronate may be effective as oral therapy.
o Calcitonin can be given intramuscularly or subcutaneously, but it becomes less effective after several days of use.
o Mithramycin blocks osteoclastic function and can be given for severe malignancy-related hypercalcemia. It has significant hepatic, renal, and marrow toxicity.
" Dialysis: Peritoneal or hemodialysis against calcium-free or lower calcium concentration dialysate solution is highly effective in lowering plasma calcium levels.
Surgical Care: Surgical care is directed toward reversing the underlying cause of hypercalcemia or repairing the orthopedic damage.
" Prolonged hypercalcemia due to hyperparathyroidism may warrant surgical neck exploration and removal of one or more parathyroid glands. This is particularly appropriate if evidence of nephrolithiasis, osteoporosis, reduction of renal function, neuromuscular symptoms, or radiographic bone disease is present.
" Hypercalcemia due to malignancy, especially if due to a tumor that is producing PTHrP, may require surgical resection of the tumor.
" Orthopedic complications of prolonged hypercalcemia (eg, osteoporosis), complications of Paget disease, or complications of bony metastases may require orthopedic or neurosurgical intervention.