Hyperparathyroidism

Causes

• Primary Hyperparathyroidism:
  • This is the most common cause of hypercalcemia.
  • Usually caused by a single benign tumor (adenoma) on one of the parathyroid glands (85-90% of cases).
  • Less commonly, it can be due to enlargement of two or more parathyroid glands (hyperplasia).
  • Rarely, it can be caused by parathyroid cancer.
  • Genetic syndromes, such as Multiple Endocrine Neoplasia (MEN) types 1 or 2, can also lead to primary hyperparathyroidism.
• Secondary Hyperparathyroidism:
  • Occurs when another condition causes the body to produce too much PTH, typically in response to low calcium levels.
  • Severe Vitamin D Deficiency: Vitamin D is necessary for calcium absorption, so a deficiency can lead to chronically low calcium, stimulating PTH production.
  • Chronic Kidney Failure: The most common cause. Damaged kidneys cannot convert vitamin D to its active form, and they also retain phosphorus, both of which lead to low blood calcium, triggering the parathyroid glands to overwork.
  • Severe Calcium Deficiency: Chronically low dietary calcium intake.
• Tertiary Hyperparathyroidism:
  • Develops after prolonged secondary hyperparathyroidism.
  • In this form, the parathyroid glands, after years of overstimulation (e.g., due to chronic kidney disease), become abnormally enlarged and produce excessive PTH independently of blood calcium levels, even if calcium levels are normalized.

Symptoms

• Bone and Joint Symptoms:
  • Osteoporosis (thinning of bones) and increased risk of fractures.
  • Bone pain and tenderness.
  • Joint pain.
• Kidney-Related Symptoms:
  • Kidney stones (nephrolithiasis) due to excess calcium in urine.
  • Frequent urination (polyuria).
  • Excessive thirst (polydipsia).
  • Kidney damage or failure over time.
• Digestive Symptoms:
  • Abdominal pain.
  • Nausea and vomiting.
  • Constipation.
  • Loss of appetite.
• Neurological and Psychological Symptoms:
  • Fatigue and weakness.
  • Depression and anxiety.
  • Memory problems or confusion.
  • Difficulty concentrating.
  • Headaches.
• General Symptoms:
  • Muscle weakness.
  • Heart palpitations or arrhythmias (due to calcium's effect on heart function).
  • High blood pressure.

Diagnosis

• Blood Tests:
  • Calcium Levels: Elevated blood calcium (hypercalcemia) is a key indicator.
  • Parathyroid Hormone (PTH) Levels: High PTH levels confirm that the parathyroid glands are overactive. The combination of high calcium and high PTH is characteristic of primary hyperparathyroidism.
  • Vitamin D Levels: To check for vitamin D deficiency, which can cause secondary hyperparathyroidism.
  • Phosphorus Levels: Often low in primary hyperparathyroidism.
  • Kidney Function Tests: (Creatinine, GFR) to assess kidney health and rule out kidney disease as a cause of secondary hyperparathyroidism.
• Urine Tests:
  • 24-hour Urine Calcium: Measures calcium excretion in urine, which can help differentiate causes of high calcium.
• Bone Mineral Density Test (DEXA scan): To assess for bone loss (osteoporosis) caused by prolonged PTH excess.
• Imaging Tests (to locate the affected gland(s) before surgery):
  • Sestamibi Scan: A nuclear medicine scan that uses a radioactive tracer taken up by overactive parathyroid glands.
  • Ultrasound of the Neck: To visualize the parathyroid glands.
  • CT Scan or MRI: May be used in more complex cases, especially if initial imaging is inconclusive.

Treatment

• For Primary Hyperparathyroidism:
  • Surgery (Parathyroidectomy): The definitive treatment. The surgeon removes the overactive parathyroid gland(s). This is highly effective in curing the condition.
  • Observation (Watchful Waiting): For asymptomatic patients with mild elevation of calcium and no complications, regular monitoring of blood calcium, kidney function, and bone density may be an option.
  • Medications:
    • Cinacalcet (Sensipar): A calcimimetic drug that mimics calcium, tricking the parathyroid glands into releasing less PTH. Used for patients who cannot undergo surgery or for severe hypercalcemia.
    • Bisphosphonates: (e.g., alendronate) Can help strengthen bones and reduce calcium levels.
    • Hormone Replacement Therapy (HRT): For postmenopausal women, can help maintain bone density but does not address the underlying parathyroid issue.
• For Secondary Hyperparathyroidism:
  • Treat the Underlying Cause:
    • Vitamin D Supplementation: To correct vitamin D deficiency.
    • Calcium Supplements: If due to dietary calcium deficiency.
    • Phosphate Binders: For chronic kidney disease patients to reduce phosphorus levels.
    • Calcimimetics: (e.g., cinacalcet) To reduce PTH levels in chronic kidney disease.
    • Active Vitamin D Analogs: (e.g., paricalcitol, doxercalciferol) To help manage calcium and PTH in kidney disease.
• For Tertiary Hyperparathyroidism:
  • Surgery (Parathyroidectomy): Often necessary, as the glands have become autonomous. Usually, 3.5 of the 4 glands are removed, or sometimes all four with reimplantation of a small piece of parathyroid tissue elsewhere.

Deciding About Parathyroid Surgery

Primary hyperparathyroidism is one of the few common conditions that an operation cures outright. Most of the harm from waiting is quiet, to bone and kidney, which is why the decision about surgery is made on tests rather than on how you feel.

Who is advised to have surgery

Anyone with symptoms, kidney stones, or a fracture is offered surgery. For people who feel well, it is still advised when calcium is more than about 1 mg/dL above the upper limit of normal, when age is under 50, when bone density shows osteoporosis, when kidney function is reduced, or when kidney imaging shows stones or the urine calcium is high. Meeting none of those criteria makes monitoring reasonable, but many people who qualify for surgery are never told so.

What the operation involves

When imaging locates a single overactive gland, a minimally invasive parathyroidectomy through a small neck incision takes under an hour, is often done as a same-day procedure, and cures the condition in the large majority of cases; experienced parathyroid surgeons have the best results, so the referral matters. Calcium can dip afterward as the bones take it back up, so calcium and vitamin D are taken for a period and tingling around the mouth or fingers is reported promptly.

Watching safely if surgery is deferred

Monitoring means calcium and kidney function yearly, a bone density scan every one to two years, and kidney imaging if stones are suspected. Restricting dietary calcium does not help and raises parathyroid hormone further, so normal intake continues. Correcting vitamin D deficiency is safe and recommended before and after surgery. Alendronate protects bone in people who decline or cannot have surgery, although it does not lower the calcium. Our bone health after 50 guide covers the rest of the plan.

Medications, heat, and the mimics

Hydrochlorothiazide and lithium raise calcium and are reviewed when the diagnosis is made. Dehydration pushes calcium higher and raises the chance of kidney stones, so fluid intake matters more here than in most of the country; our kidney stone prevention article covers what that looks like in practice. A 24-hour urine collection distinguishes primary hyperparathyroidism from familial hypocalciuric hypercalcemia, a harmless inherited pattern that surgery does not fix, and from the secondary form caused by chronic kidney disease.

Signs that cannot wait

Confusion, severe nausea, extreme thirst, or marked weakness with a known high calcium can mean a hypercalcemic crisis and needs emergency care, usually intravenous fluids. Our endocrine team arranges the workup and surgical referral. NIDDK and MedlinePlus publish patient guidance on diagnosis and surgery.

If your calcium has been high on more than one test and no one has discussed surgery, schedule a visit.