It occurs when the parathyroid glands enlarge and release too much PTH, causing a high level of PTH in the blood.
There are several reasons why this happens in patients with kidney disease:
- High levels of phosphorus in the blood.
- The kidneys can not make vitamin D active (needed to absorb calcium).
- Lower levels of calcium in the blood.
Secondary hyperparathyroidism can cause bone disease. It can also cause the accumulation of calcium in tissues and organs such as the heart and blood vessels.
What are the parathyroid glands?
The parathyroid glands are four small glands that are found near the thyroid gland in the neck.
Each one is the size of a pea. The parathyroid glands produce and release parathyroid hormone (hormones are secretions made by your body to help your body work and keep it healthy).
What is parathyroid hormone (PTH)?
Parathyroid hormone (also called PTH) controls the amount of calcium in the blood and inside the bones.
The release of PTH is activated and deactivated depending on the levels of calcium in your blood. For example, if the level of calcium in the blood decreases, the parathyroid glands will release more PTH, this will cause the bones to release calcium and increase the level of calcium in the blood.
Most symptoms of secondary hyperparathyroidism are due to the underlying cause. People with vitamin D deficiency may notice muscle pain and weakness, or pain in the bones.
In severe cases, they can develop osteomalacia (soft bones) that can cause fractures and bone deformity (in children this is rickets).
How does secondary hyperparathyroidism cause bone disease?
Your bones are constantly changing. There are cells that create new bone and cells that remove old bone. This process is known as “bone turnover”.
If you have secondary hyperparathyroidism, bone turnover is high. This means that the cells that remove the bone work faster than the cells that create new bone, which causes the bones to become weak and brittle. This can increase your chances of having bone pain and fractures.
There are several treatments to cure secondary hyperparathyroidism. These include some medications, surgery and control of blood phosphorus levels.
There are three medications for secondary hyperparathyroidism: vitamin D supplements, active vitamin D (or vitamin D analogues), and cinacalcet. If you have secondary hyperparathyroidism, talk to your healthcare provider about the right treatment for you.
Vitamin D supplements: You need active vitamin D to absorb calcium from your intestines into the blood.
Without enough active vitamin D, your calcium level decreases and the parathyroid glands release too much PTH. Therefore, you should take vitamin D supplements if your blood level of vitamin D (also called 25-hydroxy vitamin D) is too low.
Vitamin D analog: if your kidneys can no longer produce active vitamin D (also called 1,25-dihydroxy vitamin D). Your health care provider will tell you the type and amount of vitamin D that is best for you.
Cinacalcet: Cinacalcet is a medication that acts directly on the parathyroid glands to reduce PTH in the blood.
Cinacalcet acts like calcium, so the body believes there is more calcium in the blood. It is a pill that takes once a day and is only for dialysis patients. Cinacalcet may increase your chances of having low levels of calcium in your blood.
Parathyroidectomy is an operation that removes the parathyroid glands. This operation is only for very severe cases of hyperparathyroidism that can not be treated with medication.
3. Check your blood phosphorus levels:
Because high levels of phosphorus in the blood increase the release of PTH, it is important to keep phosphorus in blood in a normal range using diet and phosphate binders.