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The parathyroid gland is a set of four or more pea-sized organs in the neck. Its main job is to make parathyroid hormone (PTH), which controls calcium levels in your bloodstream.
When the parathyroid gland is overactive (hyperparathyroidism), excess PTH is produced, leading to a rise in blood calcium levels. If blood calcium levels get too high (hypercalcemia), symptoms and complications like bone loss and kidney problems can develop.
This article reviews the types, causes, diagnosis, and treatment of hyperparathyroidism. It also discusses the role of calcium and vitamin D in disease development and management.
Are the Parathyroid and Thyroid Glands the Same?
While similar in name and location (in the neck), the parathyroid and thyroid glands share no connection. The thyroid gland regulates metabolism and releases thyroid hormones into the bloodstream.
The two main types of hyperparathyroidism are:
Primary hyperparathyroidism is a parathyroid gland disease that results in excess PTH production.
The excess PTH pulls calcium into the bloodstream from the bones. The PTH also signals the gut to absorb more calcium and the kidneys to hold on to calcium and not lose it through urine. All of these PTH-driven actions result in elevated blood calcium levels.
Three causes of primary hyperparathyroidism are:
Risk Factors for Primary Hyperparathyroidism
Factors that increase a person's risk for primary hyperparathyroidism include:
(Note that when research or health authorities are cited, the terms for sex or gender from the source are used.)
Secondary hyperparathyroidism is not a disease of the parathyroid gland. Instead, it's a normal and appropriate reaction of the parathyroid gland to another health problem going on in the body that is causing low blood calcium levels.
The low blood calcium levels are most commonly due to vitamin D deficiency or chronic kidney disease.
Vitamin D Deficiency
Vitamin D is created by your body when your skin is exposed to the sun. Vitamin D can also be obtained through supplements or foods like salmon, tuna, egg yolk, and vitamin D-fortified orange juice.
Since vitamin D plays a role in ensuring sufficient calcium absorption in the gut, a deficiency can lead to low calcium levels.
Vitamin D deficiency has many potential causes, including:
Chronic Kidney Disease
Chronic kidney disease leads to an abnormality in kidney vitamin D activation. As a result of insufficient vitamin D levels in the body, low calcium levels develop. The low calcium levels trigger the parathyroid gland to release parathyroid hormone in an attempt to raise calcium levels.
Related: Common Causes of Chronic Kidney Disease
Symptoms of hyperparathyroidism depend on the type.
Most people with primary hyperparathyroidism have no or minimal symptoms.
If symptoms are present, they are due to high blood calcium levels and include:
Long-term manifestations of primary hyperparathyroidism include:
The symptoms of secondary hyperparathyroidism are related to the underlying condition.
For example, a person with secondary hyperparathyroidism from vitamin D deficiency may have muscle aches or mild weakness. If the vitamin D deficiency is severe, symptoms of rickets or osteomalacia can develop, such as:
Vitamin D deficiency also increases a person's risk for osteoporosis and fractures.
Secondary hyperparathyroidism from chronic kidney disease is also linked to osteoporosis and bone fractures. In addition, it can raise the risk of death from heart disease and anemia, although more research is needed to understand these connections.
Very rarely, secondary hyperparathyroidism from chronic kidney disease can lead to calciphylaxis, a condition associated with skin necrosis (tissue death) and severe open wounds that are difficult to heal.
The diagnosis of hyperparathyroidism is based on results from a blood calcium test and blood parathyroid hormone test.
With primary hyperparathyroidism, most individuals will have a high calcium and PTH level.
With secondary hyperparathyroidism, individuals have a high PTH and a normal or low blood calcium level. Additional blood tests, such as vitamin D and creatinine levels (a measure of kidney function), are also ordered to determine the cause of secondary hyperparathyroidism.
When evaluating for hyperparathyroidism, healthcare providers usually order studies besides blood tests to check for disease complications, especially bone loss and kidney stones.
Results from these studies also help guide management, like whether parathyroid surgery is needed.
These studies include:
Surgical removal of the parathyroid gland (parathyroidectomy) is the only cure for primary hyperparathyroidism. Nonsurgical therapies may be advised in certain situations.
Parathyroidectomy for primary hyperparathyroidism has a cure rate of 95% to 98%. It's indicated in all people with symptoms of primary hyperparathyroidism.
In asymptomatic individuals, surgery is indicated if one or more of the following criteria is met:
Requires Experienced Endocrine Surgeon
If surgery is indicated or requested, it should be performed by a highly skilled and experienced endocrine surgeon (a type of general surgeon that operates on hormone-producing glands in the body).
Learn More: Parathyroid Surgery: Everything You Need to Know
Nonsurgical therapies for primary hyperparathyroidism are generally only considered in people who cannot tolerate surgery or who have a mildly high calcium level and no symptoms or evidence of complications (e.g., low bone density or the presence of kidney stones).
The main aim of nonsurgical therapies is to control blood calcium levels so they don't get too high and cause complications.
Such therapies might include:
Appropriate calcium intake/supplementation is also advised.
Nutritional guidelines from the Institute of Medicine (IOM) are generally followed for calcium. The IOM recommends:
What Are Some Calcium-Rich Foods?
Foods rich in calcium include milk and other dairy products (e.g., cheese or yogurt), beans, almonds, sesame seeds, calcium-fortified orange juice, and leafy green vegetables like kale and spinach.
Related: The 6 Best Calcium Supplements of 2023
The treatment of secondary hyperparathyroidism involves correcting the root cause.
For instance, people with vitamin D deficiency from poor food intake or low sun exposure may be treated with prescription vitamin D supplements.
Vitamin D deficiency from gut malabsorption requires additional therapies like eating a gluten-free diet if diagnosed with celiac disease.
Treating secondary hyperparathyroidism from chronic kidney disease is complex and requires the careful attention of a nephrologist (a doctor specializing in kidney care).
Therapies may include taking a calcimimetic (a drug that blocks PTH release) and a vitamin D analog (a manufactured active form of vitamin D).
Keep in mind that a parathyroidectomy is required to control secondary hyperparathyroidism in around 15% of people 10 years after the onset of dialysis.
Learn More: How Is Kidney Failure Treated?
The key to living well with hyperparathyroidism involves following up with your healthcare team. Whether or not you undergo surgery, close monitoring is required to ensure the right balance of calcium and PTH in your body.
For instance, if you underwent surgery for primary hyperparathyroidism, you must obtain periodic blood tests to check calcium and PTH blood levels after surgery. You will also need calcium supplements after the operation until your body adjusts.
If surgery is not performed for primary hyperparathyroidism, annual monitoring of your blood calcium levels, kidney function, and bone density is essential to ensuring no disease progression and subsequent need for surgery.
In the end, health risks will be minimized if a person's hyperparathyroidism is cured or managed well. With surgery-the only curable treatment-research has found long-term improvements in quality of life.
Hyperparathyroidism is an overactive parathyroid gland that releases excess parathyroid hormone (PTH).
Hyperparathyroidism may result from a diseased parathyroid gland (primary hyperparathyroidism) or be a normal response to compensate for low calcium blood levels (secondary hyperparathyroidism).
Primary hyperparathyroidism does not usually cause symptoms but can lead to bone loss and kidney stones if not treated. The good news is that primary hyperparathyroidism can be cured by surgically removing the parathyroid gland.
The symptoms and management of secondary hyperparathyroidism are based on the underlying cause, most commonly vitamin D deficiency or chronic kidney disease.