Figure 3.

Overall calcium homeostasis in chronic hypoparathyroidism. In chronic hypoparathyroidism in adults, overall calcium metabolism is reflected by the lack of PTH. Bone turnover is markedly decreased as is the net release of calcium from the stores in bone. Levels of active vitamin D (1.25-(OH)₂–Vit D) are low due to lack of the PTH driven 1-α-hydroxylase followed by decreased intestinal absorption of calcium. The renal tubular reabsorption of calcium is decreased. Moreover, phosphate levels are high – not illustrated in the figure.