What Are The Parathyroid Glands?

The parathyroid glands are four small pea-sized glands located next to the thyroid gland in the neck. They are part of the body’s endocrine system that produces hormones.

The parathyroid glands produce a hormone called the parathyroid hormone or PTH. Underactivity of the parathyroid glands (low PTH levels) is called hypoparathyroidism. Overactivity of the parathyroid glands (high PTH levels) is called hyperparathyroidism. Both can cause health problems if left untreated.

What Does Parathyroid Hormone Do?

The main function of the parathyroid glands is to release parathyroid hormone (PTH). PTH regulates blood calcium levels in the body. Precise control of calcium levels is critical for healthy bones, nerve, and muscle function.

Effects of parathyroid hormone in the body include:

Release of calcium from bones into the blood.
Increased absorption of calcium from food in the intestines.
Helping kidney cells to transform vitamin D into its strongest form, which helps the body to easily absorb calcium from the intestines.
Conservation of calcium from the kidneys

When parathyroid hormone levels are high, it can result in hypercalcemia (high blood calcium levels) and hypophosphatemia (low blood phosphorus levels).

What Level of Parathyroid Hormone is Too High?

The normal level of “intact” PTH in blood is 15 to 65 picograms per milliliter (pg/mL). This normal PTH range can vary among laboratories. Your healthcare provider will interpret the results with reference to the laboratory’s normal range.

Causes of Low Parathyroid Hormone Levels

Autoimmune disorders or injury to the parathyroid glands during surgery on the thyroid glands of patients can result in hypoparathyroidism (low PTH levels). This can be treated with hormone replacement therapy (injections of parathyroid hormone) in addition to calcium and vitamin D supplements.

Causes of High Parathyroid Hormone Levels

High parathyroid hormone levels mainly occur due to overactive parathyroid glands which produce too much hormone. This is called hyperparathyroidism and is a treatable condition.

The National Institute for Diabetes and Digestive and Kidney Diseases (NIDDK) estimates that about 100,000 people develop primary hyperparathyroidism in the United States each year. There are 3 types of hyperparathyroidism (too much parathyroid hormone):

Primary Hyperparathyroidism

Primary hyperparathyroidism occurs because of overproduction of parathyroid hormone by an overactive parathyroid gland. One or more of the four parathyroid glands can be enlarged.

For example, a single enlarged overactive gland may be due to a benign (noncancerous) growth called a parathyroid adenoma. The condition is called parathyroid hyperplasia when two or more parathyroid glands are enlarged. A rare genetic condition called multiple endocrine neoplasia type 1 can cause primary hyperparathyroidism. You can also develop primary hyperparathyroidism due to parathyroid cancer, but this is rare.

Other risk factors for primary hyperparathyroidism include postmenopausal women, severe calcium or vitamin D deficiency, and radiation treatment to the neck for cancer. Long-term lithium therapy, a medicine used to treat bipolar disorder, can potentially cause hyperparathyroidism by affecting calcium levels.

Enlargement of the parathyroid glands results in hypercalcemia (too much calcium in the blood), which causes health problems. Primary hyperparathyroidism surgery to remove the enlarged gland(s) is curative.

A rare genetic disorder called familial hypocalciuric hypercalcemia can raise blood calcium levels and is sometimes misdiagnosed as primary hyperparathyroidism.

Secondary Hyperparathyroidism

Secondary hyperparathyroidism occurs when another health condition causes low calcium in your blood. With time, the parathyroid glands release more PTH as the body tries to raise and normalize calcium levels.

Any condition that lowers calcium levels can trigger hyperparathyroidism, such as the following:

Chronic kidney disease
Certain intestinal diseases
Gastrointestinal surgeries such as weight loss surgery, after which the body is unable to absorb enough calcium from the gut.

The treatment for secondary hyperparathyroidism depends on the underlying cause. For instance, if the cause is severe vitamin D deficiency, it can be treated with vitamin D supplementation. When secondary hyperparathyroidism is due to renal failure, it can be treated with a medicine such as cinacalcet.

Tertiary Hyperparathyroidism

Tertiary hyperparathyroidism occurs after chronic (long-term) secondary hyperparathyroidism. In most patients with chronic kidney failure on dialysis, parathyroid gland function returns to normal after kidney transplantation. However, in some patients, the parathyroid glands never return to normal function because they have functioned abnormally for so long.

Surgical removal of the parathyroid glands is typically recommended in patients with tertiary hyperparathyroidism to protect the transplanted kidney from the negative effects of too much PTH, such as kidney stones, reduced kidney function, and dehydration.

Symptoms and Complications

Common Symptoms of High PTH

The symptoms of high PTH are actually the symptoms of a high calcium level in the blood. They can range from mild to severe and may include:

Long-Term Health Complications

The long-term health complications of hyperparathyroidism mainly occur due to too much calcium in your blood and too little calcium in your bones. Complications can include:

Osteoporosis. Low levels of calcium in the bones can result in bone loss and low bone mineral density. This can lead to weak/brittle bones that are prone to bone fractures.
Kidney stones. High calcium levels in blood can lead to excess calcium in urine. This can lead to the formation of small, hard calcium deposits in the kidneys called kidney stones. A kidney stone can cause severe pain when it passes through the narrower parts of the urinary tract.
Cardiovascular disease. The exact link is not fully understood, but high calcium levels can lead to a buildup of calcium in the blood vessels. This is linked to an increased risk of cardiovascular conditions such as high blood pressure, heart disease, heart attack, and stroke.
Skin sores and infections. These problems can develop due to the buildup of calcium in the skin.
Neonatal hypoparathyroidism. Pregnant women with severe untreated hyperparathyroidism can result in dangerously low calcium levels in the newborn baby. However, women of childbearing age rarely develop primary hyperparathyroidism.
Loss of kidney function after kidney transplant. This complication can occur in people with untreated tertiary hyperparathyroidism.

Diagnostic Procedures

How is High PTH Diagnosed?

While routine blood tests do not usually include lab work for hyperparathyroidism, high PTH is often discovered due to other lab abnormalities, such as high blood calcium. Depending on the symptoms and an individual's health history, healthcare providers may decide to check the PTH levels. High PTH can be diagnosed with a blood test to measure the intact PTH level in your blood. Your healthcare provider may also order other blood tests, such as calcium and vitamin D levels, and tests for kidney function, as well as a 24-hour urine test.

Importance of Imaging

Imaging tests can help in diagnosis and treatment planning for hyperparathyroidism (high PTH). These include a parathyroid scan (sestamibi scan) to identify which glands are producing too much PTH, ultrasound imaging of the parathyroid glands and/or kidneys, and a bone density test to check for bone thinning.

How Do You Get Your Parathyroid Levels Down?

Treatment depends on the type of hyperparathyroidism, primary vs. secondary.

Surgical and Medical Treatments for Primary Hyperparathyroidism

Parathyroidectomy (surgical removal of an enlarged parathyroid gland) can cure primary hyperparathyroidism. Healthcare providers are more likely to recommend parathyroid surgery to people below 50 years of age and those who have high blood calcium levels, high urine calcium or creatinine levels, kidney stones, or osteoporosis.

People who don’t undergo parathyroid surgery are closely monitored and may be prescribed the following medications:

Bisphosphonates to prevent calcium loss from bones and improve bone density. Examples include alendronate (Fosamax), ibandronate (Boniva), zoledronic acid (Zometa), and etidronate (Didronel).
Calcimimetics to mimic calcium in the tissues and cause the parathyroid glands to make less PTH. These drugs are often used to treat secondary hyperparathyroidism. Examples include cinacalcet (Sensipar) and etelcalcetide injection (Parsabiv).
Medications to treat high blood pressure and other health complications.

Additionally, certain medications can increase the risk of hyperparathyroidism. For example, lithium, a medicine used to treat mental health conditions such as bipolar disorder, can potentially cause hyperparathyroidism by affecting calcium levels. Similarly, loop diuretics (water pills) such as furosemide (Lasix) are also associated with increased PTH levels. When hyperparathyroidism is drug-induced, your healthcare provider will discuss dosing adjustment or alternate therapy with you.

You may also need to make dietary changes to regulate how much calcium and vitamin D you are getting through foods and supplements and to prevent kidney stones.

Treatments for Secondary Hyperparathyroidism

Treatment of secondary hyperparathyroidism depends on the underlying cause. For example, if you have chronic kidney disease or kidney failure, you may need dialysis or a kidney transplant. You may also need to eat a kidney-friendly, low-phosphorus diet. Medications used to treat secondary hyperparathyroidism may include:

Phosphate binders to lower phosphate levels in your blood. Examples include sevelamer carbonate (Renvela) and lanthanum carbonate (Fosrenol).
Vitamin D supplement to treat low vitamin D levels.
Calcimimetics to lower PTH levels. Examples include cinacalcet (Sensipar) and etelcalcetide (Parsabiv).

When medical treatments for secondary parathyroidism don’t work or tertiary hyperparathyroidism develops, parathyroid surgery may be necessary.

Lifestyle Changes and Management Strategies

Treatment of hyperparathyroidism is complicated. If you have hyperparathyroidism (high parathyroid hormone), do not take over-the-counter supplements or herbal remedies, and do not make dietary or lifestyle changes without your doctor’s approval.

Frequently Asked Questions

What Happens If Parathyroid Hormone Is High?

If the enlargement of one or more parathyroid glands causes high parathyroid hormone levels, it is called primary hyperparathyroidism. The treatment is parathyroid surgery to remove the enlarged gland(s). If a medical condition has caused low calcium in your blood, it can trigger the release of PTH from the parathyroid glands as the body tries to raise calcium levels. This is called secondary hyperparathyroidism and can be treated with medications or surgery if the medications don’t work.

What Is The Parathyroid Rule of 3?

The rule of 3 parathyroid refers to three diagnostic findings that alert healthcare providers to the possibility of parathyroid cancer. These findings include a blood calcium level over 3 mmol/L, a parathyroid lesion over 3 cm in size, and ionic calcium over 1.77 mmol/L. Note: Parathyroid cancer is very rare.

What Is The Diet for Primary Hyperparathyroidism?

Consuming a balanced, healthful diet is essential if you have primary hyperparathyroidism. Generally, depending on the severity of your condition, low to moderate consumption of calcium and phosphorus-rich food and beverages, with a good intake of vitamin D-rich food, is recommended.

Last, staying well-hydrated by drinking plenty of water is also vital. Your doctor can refer you to a registered dietitian who can provide valuable resources and guidance on the type and amount of food to consume.

In many cases, in addition to a good diet, taking vitamin D supplement is still necessary to treat low vitamin D. If all your parathyroid tissue is removed during primary hyperparathyroidism surgery, you may need to take supplements lifelong to provide more calcium and vitamin D.

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