Parathyroid Hormone

What is parathyroid hormone?

Parathyroid hormone (PTH) is a hormone that your parathyroid glands make and release to control the level of calcium in your blood, not your bones.

Calcium is one of the most important and common minerals in your body. PTH also helps control the levels of phosphorus (a mineral) and vitamin D (a hormone) in your blood and bones.

Your hormones are chemical messengers that work hard behind the scenes to keep you healthy. And parathyroid hormone is no different. It keeps your blood calcium levels in check so your nerves, muscles and heart can function properly.

What is the function of parathyroid hormone?

Your parathyroid gland releases parathyroid hormone (PTH) when your body detects low calcium levels in your blood. These glands are embedded in the back of your thyroid.

PTH regulates calcium levels in your blood by affecting the following parts of your body:

• Bones. PTH triggers the release of small amounts of calcium from your bones into your bloodstream.
• Kidneys. PTH enables the production of active vitamin D (calcitriol) in your kidneys. PTH also signals your kidneys to keep calcium in your body rather than flushing it out through your pee.
• Small intestine. PTH signals your small intestine to absorb more calcium from the food you eat.

How does my body control parathyroid hormone levels?

Your body controls your parathyroid hormone levels by identifying how much calcium is in your blood. This is known as a feedback loop. In other words, low blood calcium levels trigger parathyroid hormone release. High blood calcium levels prevent your glands from releasing PTH.

But sometimes, an issue with your parathyroid glands can cause them to release too much or too little PTH, regardless of the feedback loop.

What conditions are related to parathyroid hormone issues?

When your parathyroid hormone levels are off balance, it causes certain health conditions.

High PTH levels (hyperparathyroidism) cause:

• High blood calcium levels (hypercalcemia)
• Low levels of phosphorous in your blood (hypophosphatemia)

Hyperparathyroidism has several possible causes. Some causes include parathyroid cancer, parathyroid adenoma and kidney disease.

Low PTH levels (hypoparathyroidism) cause:

• Low blood calcium levels (hypocalcemia)
• High levels of phosphorous in your blood (hyperphosphatemia)

Hypoparathyroidism is rare. About 3 out of 4 cases (75%) are from accidental damage to your parathyroid glands from neck or thyroid surgery. Certain genetic and autoimmune conditions can cause it as well.

Symptoms of abnormal PTH levels

PTH mainly controls the amount of calcium in your blood. So, the symptoms of low or high PTH levels are actually the symptoms of low or high blood calcium levels.

Low blood calcium can cause symptoms like:

• Brain fog or confusion
• Dry skin and brittle nails
• Muscle cramps
• Tingling in your lips, fingers or feet

High blood calcium can cause symptoms like:

• Fatigue
• Headaches
• Joint pain and bone pain
• Peeing more frequently and being thirsty

You should see your healthcare provider if you have symptoms of low or high blood calcium levels.

What test checks parathyroid hormone levels?

Your healthcare provider can check your parathyroid hormone levels with a blood test. Healthcare providers and laboratories call this test “PTH, intact.”

What are normal parathyroid hormone levels?

In general, the normal range for a PTH blood test is 15 to 65 picograms per milliliter (pg/mL). A picogram is one-trillionth of a gram.

Normal ranges for parathyroid hormone levels can vary from lab to lab. Always reference the lab’s normal range on your blood test report.

If you need a PTH level test, your healthcare provider will assess your result. They’ll let you know if you need further testing.