Hyperparathyroidism and High Calcium: What Overactive Parathyroid Glands Do to Your Bones and Kidneys
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Hyperparathyroidism happens when there is too much parathyroid hormone in the blood, which raises the calcium level in the blood [1]. It often causes no symptoms and is first spotted on a routine blood test showing high calcium. Left untreated, it can weaken bones, form kidney stones, and affect the heart and blood vessels [1]. Surgery is the most common treatment for the primary form and often cures it [2].
Quick Answer: What is hyperparathyroidism?
Hyperparathyroidism is a condition in which the body produces too much parathyroid hormone, raising blood calcium. Many people have no symptoms, but signs include thirst, fatigue, bone pain and depression. Blood tests showing high calcium and hormone together confirm it. Surgery often cures the primary form, while the secondary form is treated with medicines and by fixing the cause. [1] [2]
What the research says
Surgery improved bone density compared with observation in mild disease. In the SIPH randomized trial, 191 people with mild primary hyperparathyroidism were assigned to parathyroidectomy or observation, and 145 were analyzed at 5 years. Surgery had a significant benefit on bone mineral density at the lumbar spine, femoral neck, ultradistal radius, and total body compared with observation, while bone density in the observation group fell significantly at every site except the lumbar spine (Lundstam et al., Journal of Bone and Mineral Research, 2017 [3]).
Surgery was linked to fewer fractures and less kidney disease in a very large cohort. Among 50,958 people with primary hyperparathyroidism (26.5% treated surgically), the 10-year incidence of major osteoporotic fracture was 5.20% with surgery versus 7.91% without, and chronic kidney disease incidence was 21.2% versus 33.6%. This is observational data, so it shows association rather than proof (Sant et al., Journal of the Endocrine Society, 2024 [4]).
For some people with mild disease, the short-term benefit of surgery is hard to show. A meta-analysis of 8 studies in people with mild disease and no clear indication for surgery found no significant differences between surgery and active surveillance in bone health, quality of life, or neuropsychiatric symptoms over short-term follow-up, partly because fractures, kidney stones, and deaths were rare. The authors called for long-term data (Singh Ospina et al., Osteoporosis International, 2016 [5]).
What Is Hyperparathyroidism?
Hyperparathyroidism happens when there is too much parathyroid hormone in the blood. Parathyroid hormone is made by the parathyroid glands. The body has four of these glands, each about the size of a grain of rice, located behind the thyroid gland at the bottom of the neck [1].
Parathyroid hormone controls the body's levels of calcium and phosphorus. It keeps the right amount of calcium in the blood and in the tissues that depend on calcium to work correctly. Getting this balance right matters most for nerves and muscles, and it is critical for bone health [1].
There are two main types, and they work very differently [1]:
Primary hyperparathyroidism: one or more parathyroid glands make too much hormone, so blood calcium is high. Common causes are a noncancerous gland growth (adenoma), gland enlargement (hyperplasia), and, rarely, cancer.
Secondary hyperparathyroidism: another condition causes low calcium, so the glands overproduce hormone to compensate. Blood calcium is low or normal at first. Common causes are kidney disease, low vitamin D, and intestines that can't absorb calcium.
The four parathyroid glands behind the thyroid, and how too much parathyroid hormone raises blood calcium.
If hyperparathyroidism is not treated, the high hormone and high calcium levels can lead to many health problems over time [1].
Symptoms of Hyperparathyroidism
Symptoms of hyperparathyroidism can be so mild that they are hard to notice, or they may seem to belong to another health concern. If the condition is not treated, symptoms might get worse over time. Symptoms include [1]:
Frequent urination: urinating much more than usual.
Excessive thirst: often being thirsty.
Fatigue: tiring easily.
Weakness: feeling weak.
Bone and joint pain: aching bones and joints.
Belly pain: abdominal discomfort.
Digestive upset: nausea, vomiting, or loss of appetite.
Constipation: trouble passing stool.
Itchy skin.
Depression: feeling depressed.
Trouble concentrating: problems focusing or thinking clearly.
Many people with primary hyperparathyroidism do not have any symptoms at all. The condition is often found when a blood test done for another reason shows a high level of calcium in the blood. Because the symptoms overlap with so many other conditions, this disorder is often missed until a routine blood test shows high calcium [1].
When to see a doctor
See your healthcare professional if you have any symptoms of hyperparathyroidism. Those symptoms could be triggered by other health conditions that cause hyperparathyroidism, and some of those conditions can lead to other serious health concerns. Getting an accurate diagnosis as soon as possible matters, so the cause can be found and treatment can begin right away [1].
How It Happens: The Calcium–Hormone Balance
When the parathyroid glands are working correctly, they keep calcium and phosphorus in the blood within a healthy range. The system works like a thermostat [1]:
When there is not enough calcium in the blood, the parathyroid glands make more parathyroid hormone. The hormone triggers a release of calcium from the bones, raises the amount of calcium the small intestine absorbs from food, and lowers the amount of calcium lost in urine. Together, these changes raise blood calcium.
When there is too much calcium in the blood, the glands normally make less hormone, and the calcium level drops.
Calcium does more than build teeth and bones. It helps nerve cells send signals correctly and keeps muscles healthy. Phosphorus, another mineral controlled by parathyroid hormone, works along with calcium to keep the body healthy. Hyperparathyroidism develops when one or more of the glands stops following this balance and keeps producing a high amount of hormone [1].
Causes of Hyperparathyroidism
The causes differ between the two types [1].
Primary hyperparathyroidism
Primary hyperparathyroidism happens because of a health issue with one or more of the parathyroid glands themselves [1]:
Adenoma: a growth on a parathyroid gland that is not cancer. It is the most common cause.
Hyperplasia: two or more parathyroid glands growing larger than usual. It causes most of the other cases.
Cancer: a cancerous parathyroid tumor. It is a rare cause.
Secondary hyperparathyroidism
Secondary hyperparathyroidism happens because of another health condition that lowers the amount of calcium in the blood. The parathyroid glands respond by making too much hormone in an effort to bring blood calcium back to a healthy level [1]:
Not enough calcium: the digestive system cannot absorb enough calcium from food, often after surgery on the intestines, including weight loss surgery.
Not enough vitamin D: vitamin D keeps blood calcium healthy and helps the digestive system absorb calcium. Sunlight helps the body make it, and some comes from food.
Kidney problems: the kidneys change vitamin D into a form the body can use. When kidneys do not work as they should, usable vitamin D and calcium levels can drop.
Long-lasting kidney disease, called chronic kidney disease, is the most common cause of secondary hyperparathyroidism [1].
Tertiary hyperparathyroidism
In some people with secondary hyperparathyroidism that lasts a long time, the parathyroid glands get bigger. This is often due to end-stage kidney disease. The enlarged glands then begin to release parathyroid hormone when the body does not need it. The hormone level no longer comes down with medical treatment, and the amount of calcium in the blood becomes too high. This stage is called tertiary hyperparathyroidism [1].
Risk Factors
Risk factors for primary hyperparathyroidism include [1]:
Menopause: being a person who has gone through menopause.
Calcium deficiency: having too little calcium in the body for a long time.
Vitamin D deficiency: having too little vitamin D in the body for a long time.
An inherited disorder: a rare inherited disorder, such as multiple endocrine neoplasia type 1, that affects the parathyroid glands.
Genetic changes: changes in certain genes that can cause hyperparathyroidism.
Radiation: radiation treatment on the head or neck.
Lithium: taking the medicine lithium.
Complications
The complications of hyperparathyroidism are mainly related to the long-term effects of too little calcium in the bones and too much calcium in the blood [1]:
Osteoporosis: too much hormone causes loss of calcium from bones, leading to weak, brittle bones that break easily.
Kidney stones: too much calcium in the blood may lead to too much calcium in urine, forming small, hard calcium deposits in the kidneys. Read more in our guide to kidney stones.
Heart and blood vessel problems: high blood calcium is linked to some cardiovascular conditions, including high blood pressure, bradycardia (a heartbeat that is too slow), and arrhythmia (a heartbeat that is not regular).
How too much parathyroid hormone and high blood calcium can harm the bones, kidneys, and heart.
How Hyperparathyroidism Is Diagnosed
Hyperparathyroidism is often found when a blood test done for another reason shows a high level of calcium in the blood [2].
Blood tests
If a blood test shows high calcium, your healthcare professional will likely repeat the test. Many conditions can raise blood calcium. But hyperparathyroidism can be diagnosed when blood tests show a high level of parathyroid hormone at the same time as high calcium [2].
More testing
After diagnosing hyperparathyroidism, your healthcare professional will likely suggest more tests. These show how serious the condition is, check whether other conditions might be causing it, and see whether it is already leading to other health concerns [2]:
Bone mineral density test (DXA): shows whether bones are weak or brittle (osteoporosis). An X-ray device measures the grams of calcium and other bone minerals in part of a bone.
24-hour urine test: shows how well the kidneys work and how much calcium is in the urine. It helps gauge severity and find kidney problems that may be causing the condition.
Kidney imaging (X-ray, ultrasound, or other): shows whether kidney stones or other kidney concerns are present.
Imaging tests before surgery
If surgery is needed, imaging tests help locate the parathyroid glands that are causing the condition [2]:
Sestamibi parathyroid scan: a radioactive substance taken up by overactive parathyroid glands is tracked by a scanner. Radioactive iodine is also taken so the thyroid gland, which takes up iodine, does not block the view of the parathyroid glands. CT scanning may be combined with the scan.
Ultrasound: high-pitched sound waves sent from a small transducer bounce off tissue, and a computer turns the echoes into images of the parathyroid glands and surrounding tissue.
Treatment Options for Hyperparathyroidism
Treatment can include watchful waiting, surgery, and medicines. The right choice depends on the type, the calcium level, kidney and bone health, and symptoms [2].
Watchful waiting
Sometimes a healthcare professional may suggest no treatment right away for primary hyperparathyroidism, with regular checkups instead. This approach is called watchful waiting or medical monitoring [2]. It may be used when:
your calcium level is only a little higher than usual,
your kidneys are working well with no kidney stones,
your bone density is within the standard range or only slightly below it, and
you have no other symptoms that may get better with treatment.
If you choose watchful waiting, you will likely need regularly scheduled tests to check the amount of calcium in your blood, your bone density, and how well your kidneys are working [2].
Surgery
Surgery is the most common treatment for primary hyperparathyroidism, and it often cures the condition. During surgery, the surgeon removes the parathyroid glands that are larger than usual or that have a tumor. If all four glands are affected, the surgeon will likely remove only three glands and perhaps part of the fourth, leaving some parathyroid tissue behind that still works [2].
The operation may be done as an outpatient procedure, meaning you go home the same day without staying overnight. It is often done through very small incisions in the neck with local anesthetics that numb the neck only [2]. Complications are not common, but risks include:
Nerve damage: damage to the nerves that control the vocal cords.
Low calcium after surgery: a lasting low level of blood calcium if all the parathyroid glands are removed or damaged, so the body cannot make enough hormone to keep calcium at a healthy level.
Medicines
Medicines are used in certain situations, and each one targets a different part of the problem [2]:
Calcimimetic (cinacalcet, Sensipar): mimics calcium in the blood so the parathyroid glands make less hormone. It is used for primary hyperparathyroidism when surgery has not cured it or cannot be done, and with prescription vitamin D for secondary hyperparathyroidism in people with kidney conditions.
Bisphosphonates: prevent the loss of calcium from bones, easing osteoporosis caused by the condition. They do not treat the glands themselves, so blood calcium stays high.
Hormone replacement therapy: helps keep calcium in the bones in people past menopause who have signs of osteoporosis. It does not address the underlying parathyroid problem.
Always talk with your healthcare professional and pharmacist about the benefits and potential side effects of any medicine.
Treatment options depend on the type, calcium level, and bone and kidney health.
Self-Care and Lifestyle Steps
If you and your healthcare professional have chosen watchful waiting, several self-care steps can help prevent other health concerns from developing [2]:
Watch your calcium and vitamin D intake. Limiting how much calcium you eat or drink is not recommended for people with hyperparathyroidism. The daily recommended amount of calcium is 1,000 mg for adults ages 19 to 50 and men ages 51 to 70, and 1,200 mg for women age 51 and older and men age 71 and older. The daily recommended amount of vitamin D is 600 international units (IU) for people ages 1 to 70 and 800 IU for adults age 71 and older. Talk to your healthcare professional about how much you need.
Drink plenty of fluids. Drink enough fluids, mostly water, to make your urine look almost clear. This lowers the risk of kidney stones.
Exercise regularly. Regular exercise, including strength training, helps keep bones strong. Talk to your healthcare professional about the type of exercise that is best for you.
Do not smoke. Smoking can weaken bones and raises the risk of other serious health problems. If you smoke, talk to your healthcare professional about the best ways to quit.
Avoid medicines that raise calcium. Certain medicines, including some diuretics and lithium, can raise blood calcium. If you take these medicines, ask your healthcare professional whether you can switch to something else.
Coping and Support
Living with hyperparathyroidism often means living with uncertainty while you decide between watchful waiting, surgery, and medicines. It helps to know that this condition is highly treatable, and that the most common form is often cured with a single outpatient surgery.
Many people feel more in control when they keep a simple record of their calcium levels, bone density results, and kidney tests between visits. Sharing that record with your healthcare team makes follow-up visits more productive. If you are deciding about surgery, write down your questions in advance, and ask about the surgeon's experience with parathyroid procedures.
Lean on family and friends for help remembering test results and decisions. Support from people who know what you are going through can make the wait for test results or a surgery date easier to manage.
Preparing for Your Appointment
A high level of calcium is often found when a blood test is done as part of routine screening, tests for another condition, or tests looking for the cause of general symptoms. Talk to your healthcare professional about your results if they show high blood calcium.
What you can do before the visit
Write down all symptoms, including those that seem unrelated. Fatigue, aches, and concentration problems can all point to high calcium.
List all medicines, vitamins, and supplements with doses. Lithium and some other medicines can raise calcium.
Note your diet, especially calcium and vitamin D intake, to help your professional see whether you are getting enough.
Bring a family member or friend to help you remember the discussion.
Write down questions to make the visit more productive.
Questions to ask your healthcare professional
Do I have hyperparathyroidism?
What test do I need to confirm the diagnosis or find the cause?
Should I see a specialist in hormone disorders (an endocrinologist)?
If I have hyperparathyroidism, do you recommend surgery? What treatment can I have other than surgery?
I have other health conditions. How can I best manage them together?
Do you have printed material about hyperparathyroidism that I can take home?
What your doctor may ask you
Have you been feeling depressed?
Do you often feel tired, tire easily, or feel generally unwell?
Are you feeling any unexplained aches and pains?
Are you often forgetful, absent-minded, or unable to concentrate?
Are you often thirsty? Do you urinate more than usual?
What medicines do you take, and what is your diet like? This helps show whether you are getting enough calcium and vitamin D.
Bottom Line
Hyperparathyroidism is a hormone imbalance that quietly raises calcium in the blood, often without any symptoms. It is usually discovered on a blood test done for another reason. Left unchecked, it can weaken bones, form kidney stones, and strain the heart and blood vessels.
The condition comes in two forms, each with a different story. Primary hyperparathyroidism is most often caused by a noncancerous growth on one of the four rice-grain-sized glands at the base of the neck, and surgery, often a same-day procedure, is the most common treatment and frequently cures it. Secondary hyperparathyroidism is the body's response to low calcium, most commonly from long-lasting kidney disease, low vitamin D, or a digestive system that cannot absorb calcium, and it is managed with medicines and by treating the underlying cause.
Your next step: if a blood test has shown high calcium, or you have unexplained fatigue, bone pain, or kidney stones, ask your doctor about a parathyroid hormone test and a referral to an endocrinologist. An early, accurate diagnosis is the fastest way to protect your bones, kidneys, and heart.
Frequently Asked Questions
What is hyperparathyroidism?
Hyperparathyroidism happens when there is too much parathyroid hormone in the blood. The four parathyroid glands, each the size of a grain of rice, sit behind the thyroid and control calcium and phosphorus levels. Too much hormone raises blood calcium and can cause health problems.
What are the symptoms of hyperparathyroidism?
Symptoms include urinating much more than usual, frequent thirst, tiring easily, feeling weak, bone and joint pain, belly pain, nausea, vomiting, loss of appetite, constipation, itchy skin, depression, and problems concentrating. Many people with the primary form have no symptoms at all.
What causes primary hyperparathyroidism?
The most common cause is a noncancerous growth on a parathyroid gland called an adenoma. Two or more glands growing larger than usual, called hyperplasia, causes most of the other cases. A cancerous tumor is a rare cause.
What causes secondary hyperparathyroidism?
Secondary hyperparathyroidism is caused by another condition that lowers blood calcium, making the glands overproduce hormone. The most common cause is long-lasting kidney disease. Low vitamin D and poor calcium absorption, often after intestinal surgery, also cause it.
Is hyperparathyroidism dangerous?
Without treatment, long-term high calcium can lead to osteoporosis (weak, brittle bones), kidney stones, and heart and blood vessel problems such as high blood pressure, slow heartbeat, and irregular heartbeat.
How is hyperparathyroidism diagnosed?
Diagnosis uses blood tests showing high calcium and high parathyroid hormone at the same time. Further testing includes a bone mineral density test (DXA), a 24-hour urine test, and kidney imaging. A sestamibi scan or ultrasound locates the overactive glands before surgery.
What is the treatment for hyperparathyroidism?
Treatment includes watchful waiting for mild cases, surgery (the most common treatment for the primary form, which often cures it), and medicines such as cinacalcet (Sensipar), bisphosphonates, and hormone replacement therapy.
Can hyperparathyroidism be cured?
Surgery often cures primary hyperparathyroidism. The surgeon removes the enlarged or tumorous gland(s), usually leaving some working tissue behind. Secondary hyperparathyroidism is treated by addressing the underlying cause with medicines.
What should I eat or avoid with hyperparathyroidism?
Do not limit dietary calcium, but follow daily recommendations: 1,000 mg of calcium for most adults and 1,200 mg for women over 50 and men over 70, plus 600 to 800 IU of vitamin D. Drink plenty of water, avoid smoking, and ask about switching medicines that raise calcium.
Who is at risk for hyperparathyroidism?
Risk factors include being past menopause, long-term calcium or vitamin D deficiency, a rare inherited disorder such as multiple endocrine neoplasia type 1, certain genetic changes, radiation treatment on the head or neck, and taking lithium.
Related Reading
Parathyroidectomy: Surgery, Success Rate and Recovery explains parathyroid surgery and recovery.
Parathyroid Scan (Sestamibi): Finding Overactive Glands Before Surgery explains the scan that finds overactive parathyroid glands before surgery.
Calcium Blood Test: Normal Range and What High or Low Calcium Means explains the normal calcium range and what high or low results mean.
References
Mayo Clinic Staff. Hyperparathyroidism - Symptoms & causes. Mayo Clinic. September 19, 2025. https://www.mayoclinic.org/diseases-conditions/hyperparathyroidism/symptoms-causes/syc-20356194
Mayo Clinic Staff. Hyperparathyroidism - Diagnosis & treatment. Mayo Clinic. September 19, 2025. https://www.mayoclinic.org/diseases-conditions/hyperparathyroidism/diagnosis-treatment/drc-20356199
Lundstam K, Heck A, Godang K, et al. Effect of surgery versus observation: skeletal 5-year outcomes in a randomized trial of patients with primary HPT (the SIPH study). Journal of Bone and Mineral Research. 2017;32(9):1907-1914. PMID 28543873. https://doi.org/10.1002/jbmr.3177
Sant VR, ElNakieb Y, Lehmann CU, et al. Patient characteristics, management, and outcomes in a novel cohort of primary hyperparathyroidism. Journal of the Endocrine Society. 2024;8(8):bvae096. PMID 38988672. https://doi.org/10.1210/jendso/bvae096
Singh Ospina N, Maraka S, Rodriguez-Gutierrez R, et al. Comparative efficacy of parathyroidectomy and active surveillance in patients with mild primary hyperparathyroidism: a systematic review and meta-analysis. Osteoporosis International. 2016;27(12):3395-3407. PMID 27562567. https://doi.org/10.1007/s00198-016-3715-3
Medical disclaimer
This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. The clinical information in this guide reflects source material last reviewed in September 2025.
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