Viera Spustová, Ingrid Lajdová
Calcium is the fifth most abundant element in the human body. It ensures a wide range of biological functions and plays a key role in skeletal mineralization. Calcium balance is dependent on three main mechanisms: intestinal absorption, renal reabsorption and bone turnover. These mechanisms are regulated by integrated hormonal system including parathyroid hormone, vitamin D (1,25-dihydroxyvitamin D3), ionized calcium itself and their corresponding receptors in gut, kidney and bone. In healthy adults, calcium balance is relatively neutral when calcium intake ranges between 1 000-1 200 mg/day. However, calcium balance in CKD is poorly understood. This brief review focuses on the key mechanisms in the gut, kidney and bone involved in the regulation of calcium metabolism in CKD patients.