Normally, low blood calcium triggers an increase in parathyroid hormone (PTH) which raises the calcium level. When the calcium level goes high, the PTH is autonatically reduced which lowers the calcium level.
In Primary Hyperparathyroidism, however, this amazing feedback mechanism doesn't kick in when the PTH gets too high due to a parathyroid gland disorder and you will have high calcium and high PTH levels.
In Secondary Hyperparthyroidism, the disorder is due to an underlying condition which causes low blood calcium levels. Here, the PTH remains high until whatever caused the low calcium in the first place has been treated. So you will have low or normal calcium and high PTH. You may also have high phosphate or low vitamin D too.
The low calcium levels may be caused by
Symptoms relate to the underlying causes above so may include
What tests do I need?
If you or your doctor suspect sceondary hyperparathyroidism, you should get the following tests done:
Treating the underlying problem usually brings the calcium and PTH levels back to normal. Sometimes parathyroid surgery may be necessary. In secondary hyperparathyroidism, usually all four of the parathyroid glands are affected.
Patients with chronic kidney failure are usually given calcium and vitamin D, and are told to avoid phosphate in their diet. A medication called cinacalcet (Sensipar) may also be recommended. Sometimes, dialysis or a kidney transplant may be needed.
Sometimes, more often in those with kidney problems, one of the parathyroids becomes autonomous and starts producing too much parathyroid hormone after the underlying cause has been treated. You will have high calcium and high PTH. lThis, then, is called Tertiary Hyperparathyroidism. If this happens the offending parathyroid is usually removed surgically. Sometimes this may, in turn, lead to hypocalcaemia due to the long term or chronic affect on the bone.
Other complications include: