This is the term used to describe the condition that results when parathyroid glands work harder then normal. What are the parathyroid glands? We normally have 4 or 5 parathyroid glands. These are tiny oval bodies situated in the neck behind the thyroid gland, near to the voice box, underneath the Adam’s Apple.
The parathyroid glands play an important role, together with the kidneys, in keeping a normal balance of calcium and phosphate in the body. Normal calcium and phosphate balance helps to make bones strong and keeps them healthy.
In a healthy person this happens as follows:
The parathyroid glands produce a hormone called PTH (parathyroid hormone). Together with vitamin D, produced by the kidneys, it helps the gut to absorb calcium into the bloodstream from the food that we eat. This means that there is plenty of calcium available to maintain healthy bones and teeth and for the body to perform other functions in which calcium is important. PTH also helps the kidneys to get rid of waste phosphate in the blood into the urine.
When there is kidney damage, the kidneys may stop making active vitamin D and are unable to get rid of waste phosphates into the urine. This has 2 effects:
Firstly, the gut is unable to absorb as much calcium as before. Unable to detect enough calcium in the bloodstream, the parathyroid gland produces more and more PTH. In order to find enough calcium, in response to the extra PTH, the body robs it from the next best source, your bones, making them weak, causing ‘renal bone disease’. This, in turn, releases more phosphate into the bloodstream because bones are made not only of calcium but also of phosphate.
Secondly, the extra levels of phosphate in your bloodstream disguises real calcium levels in your blood making them appear lower, leading the parathyroid glands to demand more calcium and therefore produce even more PTH and leading to further breakdown of your bones. How can calcium levels be controlled in kidney failure? Your doctor will want to control your PTH levels carefully. Depending on the individual, this can take several forms. For example, by giving you extra calcium, controlling the level of phosphate in your bloodstream with tablets or giving you active vitamin D. However, if PTH is not controlled, your doctor may recommend that the parathyroid glands are surgically removed. To learn about surgery to remove the parathyroid glands please look at the leaflet on parathyroidectomy