Hypoparathyroidism, rhabdomyolysis, osteomalacia, acute pancreatitis & dehydration, rickets; extensive tissue damage eg, severe burns; myotonia congenita, heart disease particularly in digitalised patients. Bone binding sites saturation. Monitor serum Na, K, phosphate, Ca conc & renal function every 12-24 hr during therapy. Chronic renal disease, severe renal insufficiency. Not recommended during pregnancy & lactation.