Last reviewed 01/2018

Given the range of roles for calcium within the body, it is important to maintain its free extracellular concentration within narrow limits. Assuming an adequate supply of dietary calcium, this is achieved through:

  • efficient gastrointestinal absorption
  • free exchange with bone stores; the most important buffer for immediate changes of calcium concentration
  • renal excretion of calcium
  • hormonal influences on the preceding functions:
    • vitamin D; promotes calcium and phosphate absorption within the gut and mineralisation of bone
    • parathyroid hormone; promotes increased reabsorption of bone and reabsorption of calcium but not phosphate within the kidneys
    • calcitonin; promotes mineralization of calcium and phosphate into bone

Additionally, there is a small amount of calcium excretion within sweat which become more significant in extremes of heat and low humidity.