[Homeostasis of calcium in the organism].

Calcium is one of the essential ions necessary for normal functioning of the organism. The serum calcium concentration under physiological conditions is kept within narrow range between 2.25 to 2.65 mmol/l. This is possible using the complex interaction of various hormones: parathyroid hormone (PTH), active metabolites of vitamin D (primarily 1,25(OH)2D3) and calcitonin (CT). The three target organs are also involved in maintenance of calcium homeostasis: gut, kidney and bone. These are directly or indirectly the target organs of calciotropic hormones. The calcium metabolism and, therefore, calcium balance in the organism are dependent on many various factors such as: age, sex, nutritional condition, illnesses and prescribed medication.