Hypercalcaemia is what you call the electrolyte disturbance where you have an abnormally high plasma calcium ion level.
Symptoms include abdominal pain, malaise, nausea/vomiting, polydipsia, polyuria, dehydration, weight loss, constipation, fits, psychosis, depression, anorexia, confusion, drowsiness, loss of consciousness.
Cardiac arrests and calcifications such as renal calculi and corneal calcifications may occur.
The most common causes of hypercalcaemia are hyperparathyroidism, secondary bone metastases and ectopic PTH (Parathyroid hormone) secretion. Other causes include multiple myeloma, sarcoidosis and vitamin D overdose.
Treatment: find the underlying cause and treat that. Rehydrate with normal saline, correcting hypokalaemia and hypomagnesaemia while watching the electrolytes carefully. Consider giving frusemide. stop thiazide diuretics. Bisphosphonates such as clodronate, pamidronate or etidronate may be necessary to stop osteoclastic activity and are the treatment of choice for neoplastic causes of hypercalcaemia.
Other treatments include giving phosphates, corticosteroids, mithramycin and calcitonin.