endocrine and metabolic disorders
Hypocalcemia
Treatment of Hypocalcemia
IVcalcium gluconatefor tetany Oral calcium for postoperative hypoparathyroidism Oral calcium andvitamin Dfor chronic hypocalcemia and should be given slowly and with continuous ECG monitoring after checking for (and correcting) Hypokalemia . When tetany is associated with Hypomagnesemia , it may respond transiently to calcium or potassium administration but is permanently relieved only by repletion of magnesium, typically given as a 10% magnesium sulfate solution (1 g/10 mL) IV, followed by oral Infusions of calcium are hazardous in patients receivingdigoxinand should be given slowly and with continuous ECG monitoring after checking for (and correcting) hypokalemia. In transient hypoparathyroidism after thyroidectomy or partial parathyroidectomy, supplemental oral calcium may be sufficient: 1 to 2 g of elemental calcium/day may be given ascalcium gluconate(90 mg elemental calcium/1 g) orcalcium carbonate(400 mg elemental calcium/1 g). Subtotal parathyroidectomy may cause hypocalcemia that is particularly severe and prolonged, particularly in patients with chronic kidney disease or in patients from whom a large tumor was removed. Prolonged parenteral administration of calcium may be necessary postoperatively; supplementation with as much as 1 g/day of elemental calcium (eg, 111 mL/day ofcalcium gluconate, which contains 90 mg elemental calcium/10 mL) may be required for 5 to 10 days before oral calcium andvitamin Dare sufficient. Elevated serum alkaline phosphatase in such patients may be a sign of rapid uptake of calcium into bone. The need for large amounts of parenteral calcium usually does not fall until the alkaline phosphatase concentration begins to decrease. In chronic hypocalcemia, oral calcium and occasionallyvitamin Dsupplements are usually sufficient: 1 to 2 g of elemental calcium/day may be given ascalcium gluconateorcalcium carbonate. In patients without renal failure or hypoparathyroidism,vitamin Dis given as a standard oral supplement (eg, vitamin D3, cholecalciferol 20 mcg [800 IU] once/day).Vitamin Dtherapy is not effective unless adequate dietary or supplemental calcium and phosphate are also supplied. For patients with renal failure,calcitriolor anothervitamin Danalog that does not require renal metabolic alteration (eg, alfacalcidiol, dihydrotachysterol) should be used. Patients with hypoparathyroidism also have difficulty converting cholecalciferol to its active form and also usually requirecalcitriol, usually 0.5 to 2 mcg orally once a day. Pseudohypoparathyroidism can occasionally be managed with oral calcium supplementation alone, butcalcitriolat the above dose may be needed. Dihydrotachysterol is usually given orally at 0.8 to 2.4 mg once a day for a few days, followed by 0.2 to 1.0 mg once a day. Alfacalcidiol is not available in the United States. Use ofvitamin Danalogs can be complicated byvitamin Dtoxicity, with severe symptomatic hypercalcemia. Serum calcium concentration should be monitored weekly at first and then at 1- to 3-month intervals after calcium concentrations have stabilized. The maintenance dose ofcalcitriolor its analog, dihydrotachysterol, usually decreases with time. Hypoparathyroidism that does not respond adequately to calcium andvitamin Dsupplementation responds to treatment with recombinantparathyroid hormone(rhPTH 1-84), decreasing hypercalciuria and improving bone strength. Because recombinant PTH has been shown to increase the risk of osteosarcoma in animal testing, it has been available to patients in the United States only through a special risk evaluation and mitigation strategy program (www.natpararems.com). 