What Are the Dangers of High Calcium Levels in the Blood?

An elevated blood calcium level is called hypercalcemia and can cause serious complications that include osteoporosis, kidney stones, kidney failure, nervous system problems and arrhythmia, explains Mayo Clinic. The most common cause of hypercalcemia is an overactive parathyroid gland. Other causes include cancer, dehydration, immobility, medication and supplement use.