Oral calcium chloride in hypoparathyroidism refractory to massive doses of calcium carbonate and vitamin D.
Surgically induced hypoparathyroidism often responds satisfactorily to intravenous Ca administration, oral CaCO3 and vitamin D2. A 17-year-old girl developed hypoparathyroidism following partial thyroidectomy for thyrotoxicosis. Hypocalcemia was refractory to treatment with massive doses of vitamin D2, up to 150,000 U, 3-6 gm of oral Ca as CaCO3 and 2 micrograms of 1,25-dihydroxycholecalciferol per day. Intravenous Ca gluconate (360 mg of elemental Ca/d, in divided doses) was needed to correct tetany. After 25 days of unsuccessful therapy, oral administration of 30 ml of a 10% solution of CaCl2 (1.09 gm of elemental Ca) was followed by normalization of serum Ca (8.9 mg/dl) within 7 hours. This dose was repeated every 8 hours for 6 days and oral CaCO3 and IV Ca gluconate were discontinued. Serum Ca remained within normal range but hyperchloremic acidosis developed. This was corrected by providing, in addition to vitamin D, 2 g/d of Ca supplementation, 1 gm in the form of 10% CaCl2 solution and 1 gm as CaCO3 in two doses given simultaneously. During 12 months of observation, serum Ca, P and Cl have been consistently within normal limits. This patient was found to have achlorhydria, unresponsive to normalization of thyroid function and serum Ca. These findings indicate that refractoriness to oral CaCO3 and vitamin D may be caused by achlorhydria. Oral administration of CaCl2 solution can promptly correct this defect. Monitoring of serum Cl and CO2 is needed to avoid hyperchloremic acidosis.