As blood flows through the parathyroid glands, the amount of calcium and Vitamin D in the blood is checked. If the amount of calcium or Vitamin D is low the gland produces PTH, and if the amount of calcium is high the gland stops producing PTH. This is the function of the parathyroid glands. Through this mechanism, there is minute-to-minute control of the level of calcium in the blood. The concentration of calcium in the blood is very important to normal functioning of the body.
This is why there are four parathyroid glands, even though one gland would be enough to do the job. These glands are very active and are constantly working.
Vitamin D Deficiency
When the Vitamin D level drops, the parathyroid glands secrete more PTH which stimulates the kidneys to make more vitamin D. As a result PTH causes calcium to be released from the bones. This leads to thinning of bones, osteoporosis and fractures.
Vitamin D deficiency can occur at the same time as primary hyperparathyroidism and as around 30% of the population has Vitamin D deficiency. When Vitamin D deficiency is treated the calcium levels do not worsen, and the bone density improves. This doesn’t cure the hyperparathyroidism, but does lessen the effect of Vitamin D deficiency
Why are calcium and phosphorus so important?
Calcium is essential for good health – it plays an important role in bone and tooth development and in maintaining bone strength. Calcium is also important in nerve transmission and muscle contraction. Phosphorus is found in all bodily tissue – it is a main part of every cell with many roles and combined with calcium, phosphorus gives strength and rigidity to your bones and teeth.
The function of the parathyroid glands
The parathyroid glands are four tiny glands, located in the neck, that control the body’s calcium levels. Each gland is about the size of a grain of rice (weighs approximately 30 milligrams and is 3-4 millimeters in diameter). The parathyroids produce a hormone called parathyroid hormone (PTH).
PTH raises the blood calcium level by:
- Breaking down the bone (where most of the body’s calcium is stored) and causing calcium release
- Increasing the body’s ability to absorb calcium from food
- Increasing the kidney’s ability to hold on to calcium that would otherwise be lost in the urine
Excess parathyroid hormone causes:
- The release of too much calcium into the bloodstream
- The bones may lose calcium
- Too much calcium may be absorbed from food
- The levels of calcium may increase in the urine, causing kidney stones.
- PTH also lowers blood phosphorus levels by increasing excretion of phosphorus in the urine
If you have any questions about thyroid or parathyroid surgery, you should speak to your local doctor, who will arrange to contact your thyroid surgeon.