Differential diagnosis of abnormalities in serum calcium levels

Extracellular calcium levels are strictly regulated through actions of the two major calcium-regulating hormones, PTH and active vitamin D (1alpha,25-dihydroxyvitamin D), on their target organs including intestines, kidneys and bone. Accordingly, both hypercalcemia and hypocalcemia are mostly caused by either deregulated actions of these hormones or functional abnormalities in their target organs. This overview summarizes diseases causing serum calcium abnormalities and their differential diagnosis.