Parathyroid hormone (PTH) is produced by the parathyroid glands. These are four glands located behind the thyroid gland in a person’s neck. These glands are responsible for producing the PTH which exists to help regulate calcium levels in the bloodstream.
When your calcium level is at the high range, normal parathyroid glands stop producing PTH; when the calcium level is in the low range, the parathyroid glands produce PTH in proportion to the amount of calcium that is required by the body.
When the body's calcium metabolism is in balance, there is an even amount of bone breakdown and bone building so that the calcium storage in our body remains even and the bones remain dense and strong.
When too much PTH is produced (overactive PTH production), this is a condition called hyperparathyroidism. An elevated PTH level is not normal and should be investigated.
PTH and Primary Hyperparathyroidism
Parathyroid disease is caused by a tumor in one or more parathyroid glands that secretes excessive PTH. Normal parathyroid glands stop secreting parathyroid hormone in response to normal or elevated calcium levels in the blood. The abnormal parathyroid in primary hyperparathyroidism does not "turn-off" in response to a normal or elevated calcium level in the blood stream and therefore causes elevated levels of PTH.
In the case of primary hyperparathyroidism, drugs will not counteract the effects of elevated PTH. Symptoms of primary hyperparathyroidism include bone pain, osteoporosis (thin bones), kidney stones, and abdominal discomfort.
Elevated PTH also affects the mind and mental health. An excess of PTH can be associated with feeling of anxiety and fatigue. Other symptoms include sleep difficulty, headaches, difficulty concentrating and depression.
Elevated PTH may also have a direct toxic effect on the function of the heart muscle. Studies have shown that after a successful parathyroid operation, many (but not all of these heart problems) can significantly, if not completely, improve.
Vitamin D Deficiency
When the body does not have sufficient Vitamin D to maintain a normal calcium level, there can also be an elevation in the PTH level. This is usually a small elevation in the PTH level. However this comes about because the calcium level is low for a prolonged period and the parathyroid glands respond by producing PTH to a level above normal. This is different than primary hyperparathyroidism because the calcium level is below normal or in the low normal range. It is never normal to have a normal or high normal calcium and elevated PTH at the same time and this is not caused by Vitamin D deficiency.
Secondary hyperparathyroidism can also cause an elevated PTH level. This usually occurs from chronic kidney disease where Vitamin D is not effectively converted to its active form by the kidneys. This form of Vitamin D deficiency can result in low calcium levels and secondary hyperparathyroidism. The parathyroid hormone levels in this condition can be very high and frequently are over 100 when the upper limit of normal is 65.
Testing For Elevated PTH During Parathyroid Surgery
We use the Tosoh AIA-360 Parathyroid Hormone Analyzer for Rapid Intraoperative Parathyroid Hormone testing (IOPTH). The intraoperative PTH testing is performed on most patients undergoing parathyroid surgery. The purpose of the test is to ensure that there is a “chemical” cure to the hyperparathyroidism.
Intraoperative parathyroid hormone (IOPTH) monitoring is a test that we use to measure the parathyroid hormone level in the bloodstream before we remove the parathyroid adenoma and after we remove the parathyroid adenoma. If the parathyroid hormone level drops to 50% or more of its initial value within 10 minutes of parathyroid tumor removal, then this confirms the biochemical cure of primary hyperparathyroidism. This very specialized test is available at only a few medical centers.
Can PTH Levels Return to Normal?
Yes, but only after removal of the abnormal tumor. Elevated PTH caused by hyperparathyroidism will not fix itself in time. Only the removal of the bad parathyroid gland will cure the parathyroid disease.
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