Primary Hyperparathyroidism is much less common but much easier to explain. We will deal with that first.
Primary Hyperparathyroidism is usually due to an enlargement of one of the 4 parathyroid glands. This enlargement of the gland is benign (not malignant). The problem is that it produces too much parathyroid hormone (PTH).
The enlarged Parathyroid gland no longer pays attention to the serum calcium level. It simply puts out more PTH. This causes the serum calcium to keep rising. While high calcium is less bad than low calcium, this eventually causes trouble.
The most important issue in Primary Hyperparathyroidism is that constant high levels of PTH stimulate the Osteoclast cells that eat away bone. They keep eating away more and more bone in order to release more and more calcium into the bloodstream. This can seriously weaken bones to the point of spontaneous fragility fractures. That is serious Osteoporosis.
Primary Hyperparathyroidism is suspected when both serum calcium and PTH are high. The diagnosis is confirmed by a Parathyroid Scan. The Treatment is removal of the enlarged Parathyroid gland by surgery. This stops the loss of bone and often reverses the Osteoporosis.
Jay Ginther, MD
2009, Revised May 2011