Hypocalcaemia (lowered blood calcium) in chronic kidney disease, as well as in liver or intestinal diseases, can lead to uncontrolled production of Parathyroid hormone (PTH) is a hormone secreted by the parathyroid glands, which regulates calcium levels in the blood. PTH is secreted in response to low blood calcium levels (hypocalcaemia). An increase in calcium concentration above the normal value inhibits PTH production (negative feedback). PTH stimulates... (PTH) in the parathyroid gland. As a result, the parathyroid glands, react less and less to calcium as a stop signal (down-regulation of calcium receptors), increasing production of PTH. Increased PTH in the blood results in continuous bone The re-uptake of substances from tissues, in particular bone, into the blood. It should not be confused with absorption, the initial uptake of substances into the body, for instance from food in the intestines, through the lungs and via the skin. Reabsorption, in contrast, occurs... and eventually softening of the bones. Furthermore, the calcium released into the blood can lead to kidney stones and seriously affect the health of kidneys, heart, blood vessels and skin.