Parathyroid Gland & its Disorders

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  • 0:00 Parathyroid Glands
  • 1:15 Overactive Parathyroid…
  • 3:55 Underactive…
  • 4:50 Diagnosing the Patient
  • 5:40 Lesson Summary
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Lesson Transcript
Instructor: Adrianne Baron

Adrianne has taught high school and college biology and has a master's degree in cancer biology.

This lesson covers the basics of the parathyroid glands and the different conditions that may occur when the parathyroid doesn't function like it is supposed to. We will also touch on one treatment for parathyroid gland disorders.

Parathyroid Glands

Michelle is a new patient who is being seen in the endocrinology office where you work. You've just called her back so you can figure out what brought her into the office. Once you two are in the exam room, she begins to explain that she was monitored by her previous doctor for possible problems with her parathyroid glands. You think for a minute and remember learning that the parathyroid glands are a set of 4 very small glands that surround the thyroid gland. The hormone released by the parathyroid glands that helps to regulate calcium is PTH, also called parathyroid hormone, parathyrin or parathormone.

You let her know that Dr. Alex will be in shortly to examine her and run some tests. Upon returning to your desk, you pull out a quick guide that you often refer to in order to learn more about glands, hormones and disorders. It states that the parathyroid glands are controlled by changes in blood calcium levels. When blood calcium is low, PTH is released and if blood calcium is high, PTH is decreased. The guide then goes on to discuss some disorders that can happen if this regulation of PTH is not maintained.

Overactive Parathyroid Disorders

The first of the disorders that you read about are the ones that are caused when too much PTH is released by the parathyroid gland resulting in hyperparathyroidism. It pops into your mind that there are two different types of hyperparathyroidism: primary and secondary. You recall to yourself that primary hyperparathyroidism occurs when one or all of the parathyroid glands releases too much PTH due to some type of disease or disorder of the parathyroid glands.

This is seen a lot in people who have tumors, cancers, or other overgrowths in the parathyroid. The guide is helpful in explaining the other types since you didn't remember the details about it. The guide reminds you that secondary hyperparathyroidism is when too much PTH is released due to decreases in blood calcium caused by disorders in other parts of the body. The most common reasons for this to happen are problems with vitamin D and calcium absorption and kidney failure.

You go on to read that both types of hyperparathyroidism cause the same signs and symptoms. The first noticeable sign will show up in blood tests. Hypercalcemia is an increased amount of calcium in the bloodstream. This alone can cause it's own symptoms in the body such as bone weakness, problems with nerve signals and weakening of muscles. The guide also lets you know that it can cause problems with kidney function too, since the kidneys work harder when too much calcium is in the blood.

The lessons you learned about PTH flashes through your mind and helps you to recall most of the other signs and symptoms. They are: excessive urination, arthritis, nausea and vomiting, fatigue, kidney stones, depression and confusion. The guide fills in the other signs and symptoms of osteoporosis, loss of appetite and abdominal pain.

Another condition that you read about that can result from hyperparathyroidism is osteitis fibrosa, which is when bones are so weak they become deformed. You pause because you thought calcium is what your bones need to be strong. So why would too much calcium cause bones to become deformed?

After a little more reading, you see that PTH increases calcium by causing bones to break down to release calcium into the bloodstream. As long as too much PTH is released, then the bones will continue to break down in an effort to raise the blood calcium levels. Now it clicks! Osteitis fibrosa doesn't happen due to the calcium, it happens due to the extra PTH in the blood.

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