The role of your kidneys

Learn about the jobs of your kidneys, including how they help to control calcium, phosphate and vitamin D hormone levels

Your kidneys are important
Pair of kidneys

Your kidneys have many important jobs,1 including:

Releasing hormones1

Maintaining the acid level of your blood1

Removing waste materials, drugs and toxins from your blood1,2

Activating vitamin D1,3

Maintaining the balance of water in your blood1,4

Maintaining the balance of electrolytes (electrically charged particles) in your blood1,4

Pair of kidneys
Kidney controlling calcium, phosphate and active vitamin D levels
Which of my kidneys' jobs are relevant to secondary hyperparathyroidism?
Kidney icon

Three functions of your kidneys are relevant to the development of secondary hyperparathyroidism. 

Kidney controlling calcium, phosphate and active vitamin D levels

These are:


Helping to control the level of calcium in your blood5,6


Helping to control the level of phosphate in your blood5,6


Helping to activate vitamin D3

How do kidneys help to control calcium and phosphate levels?
Icon showing an arrow that points both up and down

Your kidneys help to balance the levels of calcium and phosphate in your blood by either increasing or decreasing the amounts they filter out.5,6

What is vitamin D hormone and how do
my kidneys help to activate it?
Icon showing vitamin D molecule

Vitamin D hormone is a molecule that your intestines need to absorb calcium from food.3

Icon showing the sun and cutlery

The basic form of vitamin D, called native or nutritional vitamin D,7 is made by your skin when exposed to sunlight.3 You also get some from food.3

Liver icon

Your liver turns the nutritional vitamin D into vitamin D prohormone, which is the precursor of vitamin D hormone.3

Kidney icon

Your kidneys and some other parts of your body convert the vitamin D prohormone into vitamin D hormone.3,8

Intestines icon

Your intestines can then use the vitamin D hormone to absorb calcium from food.3

  1. Traynor J et al. BMJ. 2006;333(7571):733–7.
  2. Inui KI et al. Kidney Int. 2000;58(3):944–58.
  3. Ross AC et al., editors. Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium [Internet]. Washington (DC): National Academies Press (US); 2011. Available from: [accessed 2021 January 26].
  4. Kwon T et al. Kidney Res Clin Pract. 2013;32(3):96–102.
  5. Cunningham J et al. Clin J Am Soc Nephrol. 2011;6:913–21.
  6. Rodriguez M et al. Am J Renal Physiol. 2005;288:F253–64.
  7. Bacchetta J et al. Clin Biochem. 2014;47(7–8):509–15.
  8. Adams JS et al. J Steroid Biochem Mol Biol. 2014;144PA:22–7.