Hyperparathyroidism

Hyperparathyroidism is a condition where one or more of your parathyroid glands is overactive and releases (secretes) too much parathyroid hormone (PTH). This can cause hypercalcemia, or high levels of calcium in your blood.

You have two pairs of parathyroid glands (four total) in your neck. Their job is to make sure you have enough calcium in your blood. They also reduce blood phosphate levels. They secrete PTH to send signals to:

• Your bones, telling them to release calcium and phosphate.
• Your kidneys, to reabsorb (hold onto) calcium and get rid of phosphate in your pee.

Your kidneys then send active vitamin D to your gut, which tells it to absorb calcium. Vitamin D also sends a signal back to your parathyroid glands, telling them when your body has enough calcium and they should stop releasing PTH.

When your parathyroid glands make more than enough PTH, your bones can lose too much calcium, making them thin and brittle. The calcium can also build up in your kidneys, blood vessels, heart and other parts of your body.

Types of hyperparathyroidism

Types of hyperparathyroidism include:

• Primary hyperparathyroidism. In primary hyperparathyroidism, a growth or enlargement of one or more parathyroid glands causes them to make too much PTH. They also don’t respond to your body’s signals that tell them to stop making PTH.
• Secondary hyperparathyroidism. If you have a condition that causes high phosphate levels, low vitamin D levels or low calcium levels, your parathyroid glands will make more PTH to try to increase your calcium levels and lower your phosphate levels. This is secondary hyperparathyroidism. It’s most common in people with chronic kidney disease (CKD).
• Tertiary hyperparathyroidism. Tertiary hyperparathyroidism happens if you have long-lasting secondary hyperparathyroidism that doesn’t respond to treatment. Your parathyroid glands become enlarged (hyperplasia) and continuously produce PTH.