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What Is the Parathyroid Gland?

The parathyroid is one of those mysterious body parts that not many people understand or know much about.  But it’s actually a vital part of our endocrine system and overall bone health.  Let’s learn all about what it is, what it does, and what happens when it malfunctions.

By
Sanaz Majd, MD,
March 27, 2014
Episode #149

I recently received an email request from a listener asking me to explain the parathyroid, hypercalcemia, and the risks involved. I love receiving listener requests for specific medical topics because this way, I know what's worrying you and how I can help.  So thank you, Corina, for writing to the House Call Doctor.

The parathyroid is really one of those mysterious and vague parts of the body that not many people understand or know much about.  But it’s actually a vital part of our endocrine system and plays a big role in our overall bone health.  Let’s learn all about what it is, what it does, and what happens when it malfunctions.

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What Is the Parathyroid Gland?

The parathyroid glands are typically 4 tiny structures (as small as grains of rice) that hide behind the thyroid gland (hence, the name “PARA-thyroid -clever, I know). They're located in your neck.  Even though the parathyroid sits behind the thyroid gland, it has a separate function.  It releases an important hormone called…yep, you guessed it…the parathyroid hormone, or PTH (see, medicine isn't always that complicated). PTH plays a crucial role in how calcium is used in your body.  Therefore, a good working parathyroid system is important for strong bone health. 

Because they hide behind the thyroid, your doctor will not be able to feel your parathyroid glands, unfortunately.  So how do we know it’s out of whack?  Well, doctors often begin their detective work using a simple blood test that checks your blood calcium levels.

What Does the Parathyroid Do?

The parathyroid is the chief of the calcium tribe that's running around in your body (it also bosses phosphorous around, too, but we’ll keep it simple for today's purposes).  It dictates what calcium living in the bone, blood stream, and kidneys needs to do.  So, when the body is low in calcium, it has to find a way to recruit more tribe members from nearby sources.  How does it do this?  In three important ways:

  1. By stealing it (from the bone):  It stimulates the bone to break down and release the stored calcium inside the bone.  By stealing this calcium, the bone becomes weaker since it just lost all its tribe members.  This can be a problem for patients with osteoporosis, or low bone density.

  2. By activating a second-in-command (Vitamin D):  The parathyroid may be the chief, but every chief needs a second-in-command, and that's Vitamin D. When the body needs more calcium, it hires (or activates) his side-kick Vitamin D in the gut to do part of the job for him.  Why does it do this?  Because Vitamin D has a notorious reputation for his superior ability to recruit young, fresh tribal members entering the region -- it increases calcium absorption in the gut from the food you ingest.  So now you know why all those over-the-counter calcium supplements are mysteriously sold with Vitamin D inside.

  3. By hiring tribal enforcers (the kidneys):  The parathyroid also enlists the help of the kidneys to act as the enforcers to keep calcium from escaping the territory. The kidneys hold onto the calcium and keep it from fleeing through the urinary river.

Parathyroid Malfunction

When danger strikes and tribal order is threatened, the parathyroid is either overactive (fierce and hostile - known as HYPERparathyroid) or underactive (overwhelmed and disheartened - known as HYPOparathyroid). Here's how the two conditions differ:

Hyperparathyroidism:  If severe enough, patients with overactive parathyroids rarely get bone pain (because of too much bone breaking down) or even dehydrated (because of too much calcium running around in the blood stream and not enough fluid to compensate for it).  There are 2 main ways this can occur:

  1. Problematic Chief (Primary Hyperparathyroidism):  We refer to this when for some reason the parathyroid goes out of whack all on its own;  the problem is within the gland itself, either due to a benign overgrowth of the parathyroid tissue (called a tumor) or cancer (which is rare).

  2. Weak Enforcers (Kidney Disease):  When the kidneys don’t do what they are told to hold onto calcium, the parathyroid gets angry and tries to compensate by overworking himself (hence, overproducing PTH).  Here, the problem is within the kidneys.

  3. Weak Second-in-Command (Vitamin D Deficiency):  Vitamin D helps calcium absorption in the gut.  So when we are severely deficient, the low circulating calcium levels may stimulate the parathyroid hormone to pump out more PTH in order to compensate.

Hypoparathyroidism:  If severe enough, patients with underactive parathyroids can get muscle cramping or twitching, or tingling/numbness sensations (due to low blood calcium levels).  Hypoparathyroid can be caused by several very rare diseases (DiGeoges Syndrome or autoimmune disorders), but it often occurs after damage to the parathyroid during combat - as in after thyroid surgery (which is rare nowadays due to advanced surgical techniques).

Diagnosis of Parathyroid Gland Problems

Patients often present without any symptoms and the diagnosis is often suspected after abnormal calcium levels (either high or low) on routine blood work.  If the calcium levels are more than just mildly out of range, your doctor may decide to further determine the cause of the parathyroid gland issue by testing the patient's levels of:

  • PTH
  • Vitamin D 
  • Bone density
  • Kidney function
  • urine calcium release

If parathyroid gland problems are suspected, your doctor may decide to refer you to an endocrinologist, the Gods of the Land (I mean gland). Venture on, my Lord of the Flies, until next time.

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Please note that all content here is strictly for informational purposes only.  This content does not substitute any medical advice, and does not replace any medical judgment or reasoning by your own personal health provider.  Please always seek a licensed physician in your area regarding all health related questions and issues.

Thyroid image courtesy of Shutterstock.

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