Primary Hyperparathyroidism
Primary hyperparathyroidism is a disorder where one or more of the four tiny parathyroid glands in your neck becomes overactive and produces too much parathyroid hormone, leading to high calcium levels in your blood that can affect your bones, kidneys, and other organs.
Table of contents
- What is Primary Hyperparathyroidism?
- What Do the Parathyroid Glands Do?
- Associated Anatomy
- How Common is Primary Hyperparathyroidism?
- What Causes Primary Hyperparathyroidism?
- What Are the Symptoms?
- Possible Complications
- How is it Diagnosed?
- Treatment Options
- Diet Considerations
What is Primary Hyperparathyroidism?
Primary hyperparathyroidism is a disorder of the parathyroid glands, which are four pea-sized glands located on or near the thyroid gland in the neck. The term “primary” means this disorder begins in the parathyroid glands themselves, rather than resulting from another health problem such as kidney failure.[1]
In primary hyperparathyroidism, one or more of these glands becomes overactive. As a result, the gland makes too much parathyroid hormone (PTH), which is a substance that helps control calcium levels in your body. Too much PTH causes calcium levels in your blood to rise too high, which can lead to health problems such as bone thinning and kidney stones.[1]
Doctors usually catch primary hyperparathyroidism early through routine blood tests, before serious problems occur. In fact, most people with this condition have no symptoms at all, and the diagnosis comes as a complete surprise during blood testing for other reasons.[1][15]
- Parathyroid glands
- Thyroid gland
- Neck
- Bones
- Kidneys
- Intestines
What Do the Parathyroid Glands Do?
The parathyroid glands have only one purpose: to make PTH, which helps maintain the right balance of calcium in your body. Calcium is especially important for nerves and muscles to work properly, and it is critical for bone health.[1][2]
PTH raises blood calcium levels in three main ways. First, it causes bone, where most of your body’s calcium is stored, to release calcium into the blood. Second, it helps your intestines absorb calcium from food. Third, it helps your kidneys hold on to calcium and return it to your blood instead of flushing it out in urine.[1]
When the level of calcium in your blood falls too low, the parathyroid glands respond within seconds and release just enough PTH to bring calcium levels back to normal. The glands tightly regulate the calcium concentration within a narrow normal range, constantly adjusting PTH output throughout the day as calcium levels fluctuate.[4][15]
Associated Anatomy
The four parathyroid glands are normally located behind the four poles of the thyroid gland at the bottom of the neck. Each parathyroid gland is about the size of a grain of rice or a pea.[2][4] Rarely, a parathyroid gland may be located elsewhere in the neck or upper chest region, and while uncommon, it’s possible to have more than four glands.[15]
How Common is Primary Hyperparathyroidism?
Primary hyperparathyroidism is one of the most common hormonal disorders. In the United States, about 100,000 people develop this condition each year. The prevalence is about one to seven cases per 1,000 adults.[3]
The condition is more common in certain groups of people. It is more common in the African-American population.[3] Women are more likely than men to develop primary hyperparathyroidism, with women diagnosed about three times as often as men.[3][19]
The risk of developing primary hyperparathyroidism increases with age. The disorder can occur in persons of any age, including pregnant women, but it is more common in persons older than 50 years. In the United States, the estimated incidence in persons older than 65 years is one case per 1,000 in men and two to three cases per 1,000 in women.[4] Most patients with primary hyperparathyroidism are postmenopausal women, with the average age at diagnosis being 55 years.[4]
What Causes Primary Hyperparathyroidism?
The most common cause of primary hyperparathyroidism is a single noncancerous growth called an adenoma on one of the parathyroid glands. An adenoma is a benign tumor that causes the gland to become overactive and make more PTH than needed.[3][15] In 85 to 97 percent of patients with primary hyperparathyroidism, the underlying cause is an adenoma in a single parathyroid gland.[4][5]
Less often, all four parathyroid glands become enlarged, a condition called hyperplasia, and produce too much PTH. This accounts for about 2.5 percent of cases. Multiple adenomas within the parathyroid glands can also occur.[4][5]
Sometimes primary hyperparathyroidism results from radiation to the neck area or the use of certain medications. Lithium therapy can be responsible for overactive parathyroid glands, with the excess activity sometimes persisting even after discontinuation of the drug. Thiazide diuretics are another medication that can sometimes contribute to the condition.[3][4]
In a small number of cases, people inherit a gene that leads to primary hyperparathyroidism. The condition can be a feature of several familial disorders, including Multiple Endocrine Neoplasia Type 1, Multiple Endocrine Neoplasia Type 2A, and familial hyperparathyroidism.[5]
Rarely, parathyroid cancer causes primary hyperparathyroidism. Fewer than 0.5 percent of cases are caused by parathyroid malignancies.[3][4]
What Are the Symptoms?
Many people with primary hyperparathyroidism have no symptoms at all, or only very mild symptoms that are hard to notice. The condition is usually diagnosed after an elevated calcium level is found incidentally during routine blood testing or tests for other conditions.[1][4][7] Today, asymptomatic cases account for about 80 percent of all diagnoses.[15]
When symptoms are present, they are related to the resulting elevated calcium levels in the blood, a condition called hypercalcemia. The symptoms of primary hyperparathyroidism are classically summarized by the phrase “stones, bones, abdominal groans, thrones and psychiatric overtones.”[5]
“Stones” refers to kidney stones, a painful condition where small clumps of calcium form in the kidneys. High calcium levels can also cause excessive urination and increased thirst.[5]
“Bones” refers to bone-related problems. Too much PTH causes more calcium to be released from the bones, which over time can result in weak bones that break easily. The classic bone disease in hyperparathyroidism is called osteitis fibrosa cystica, which results in bone pain and sometimes broken bones that occur without significant injury. Other bone conditions associated with hyperparathyroidism include osteoporosis and osteomalacia.[3][5]
“Abdominal groans” refers to digestive symptoms. These can include constipation, indigestion, nausea and vomiting, and loss of appetite. Hypercalcemia can also lead to peptic ulcers and acute pancreatitis.[4][5]
“Thrones” refers to frequent urination and constipation.[5]
“Psychiatric overtones” refers to effects on the brain and mental health. Symptoms can include tiredness, weakness, low mood, depression, trouble concentrating, confusion, forgetfulness, anxiety, memory loss, and in severe cases, even delirium or coma.[4][5][7]
Other symptoms that may occur include muscle weakness, aches and pains (particularly in joints, hands, arms, feet and legs), and itching.[5][7]
Possible Complications
If hyperparathyroidism is not treated, it can lead to several serious complications over time.[7]
Osteoporosis is a condition where bones become weaker and more likely to break. This occurs because too much calcium is removed from the bones over time.[7]
Kidney stones are another common complication. These are small clumps of calcium that form in the kidneys and can be extremely painful. High calcium levels can also lead to a decline in kidney function over time and can ultimately lead to kidney failure.[3][5]
High blood pressure can develop, which increases the risk of heart disease and stroke.[7] In some people, calcium can build up in blood vessels, the heart, and other parts of the body.[10]
How is it Diagnosed?
Primary hyperparathyroidism is often discovered when a blood test done for another reason shows a high level of calcium in the blood. If your healthcare provider suspects that you may have hyperparathyroidism, blood tests will be used to confirm the diagnosis.[8]
Persistent hypercalcemia (high calcium levels) and an elevated parathyroid hormone level are the main diagnostic criteria for primary hyperparathyroidism. If blood tests show that you have a high level of calcium and a raised (or inappropriately normal) level of parathyroid hormone at the same time, this confirms the diagnosis.[4][8][16]
After diagnosing hyperparathyroidism, your healthcare provider will likely suggest more tests to check for complications and see how serious the condition is. These additional tests may include:[3][8][16]
- Blood tests to check how well the kidneys are working
- A measure of calcium levels in urine, usually collected over 24 hours
- A bone mineral density test, called dual-energy X-ray absorptiometry (DXA), to check bone health and see if bones are weak or brittle
- Imaging tests such as ultrasound, X-ray, or CT scan to check for kidney stones
To identify the source of the excessive hormone secretion, additional imaging tests may be performed. These can include ultrasound of the neck or other specialized scans to locate which parathyroid gland has an adenoma or is enlarged.[5]
Treatment Options
Surgery, called parathyroidectomy, is the definitive treatment and the only complete cure for primary hyperparathyroidism. During this procedure, one or more parathyroid glands are removed. When performed by experienced surgeons, the procedure has success rates of 90 to 95 percent and a low rate of complications.[2][4]
Not everyone with primary hyperparathyroidism needs surgery right away. You may not need treatment if your calcium levels are not too high and are not causing you any problems. If you have asymptomatic primary hyperparathyroidism, you and your healthcare provider can have a fairly benign course for years, even a lifetime.[7][15]
Asymptomatic patients who decline surgery and meet criteria for medical management must commit to careful long-term monitoring. This includes regular blood tests to monitor calcium levels, kidney function tests, and bone density scans.[4]
If you are unable to have surgery or do not want it, you may be offered medicines to help lower your calcium levels. These medications do not cure the condition but can help manage symptoms and prevent complications.[7][11]
Diet Considerations
An important point to remember is that you should not make any changes to your diet to try to lower your calcium levels unless you have been told to by your specialist. A change in your usual diet could make your symptoms worse or cause more serious problems.[7]
Any unexplained elevation of calcium levels should be evaluated promptly to prevent complications from hypercalcemia. Your healthcare provider will give you specific guidance about diet and lifestyle based on your individual situation.[4]