Abnormal increase in blood calcium due to a disturbance of calcium-phosphate balance. It can occur in chronic kidney disease as a consequence of excessive 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... synthesis and subsequent release of calcium from bones (in 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...). Elevated calcium levels are also associated with bone tumours.