A parathyroid disorder is any condition where your parathyroid glands produce too much or too little parathyroid hormone (PTH), disrupting your body’s calcium balance. Most people have four parathyroid glands, each about the size of a grain of rice, sitting behind the thyroid in the neck. Despite their small size, these glands control calcium levels throughout your entire body, and when they malfunction, the effects can reach your bones, kidneys, digestive system, and brain.
What Parathyroid Glands Actually Do
Your parathyroid glands have one job: keep blood calcium in a tight range (normally 8.6 to 10.3 mg/dL). They do this by releasing PTH, which acts on three systems simultaneously. In bone, PTH triggers cells called osteoclasts to break down bone tissue and release stored calcium into the bloodstream. In the kidneys, PTH tells your body to hold onto calcium rather than excreting it in urine, while also flushing out excess phosphate. PTH also activates vitamin D in the kidneys, and that activated vitamin D then boosts calcium absorption from food in your intestines.
This system runs on a feedback loop. When calcium drops, the glands release more PTH. When calcium rises, they slow down. A parathyroid disorder breaks this feedback loop, either flooding the body with too much PTH or leaving it without enough.
Hyperparathyroidism: Too Much Hormone
Hyperparathyroidism is the more common category of parathyroid disorder, and it comes in three forms depending on where the problem originates.
Primary Hyperparathyroidism
In primary hyperparathyroidism, the problem starts in the parathyroid glands themselves. One or more glands overproduce PTH regardless of how much calcium is already in the blood. A single benign growth called an adenoma causes up to 85% of cases. Two adenomas account for another 4% to 5%, and enlargement of all four glands (called hyperplasia) makes up 10% to 12%. Parathyroid cancer is a rare cause.
Many people with primary hyperparathyroidism have no obvious symptoms at first. The condition is frequently caught by accident, when a routine blood test reveals elevated calcium. Over time, though, the persistent excess calcium can cause real damage. Medical students learn the classic signs through a mnemonic: “stones, bones, groans, and psychic moans.” That translates to kidney stones, weakened bones prone to fractures, abdominal problems like constipation and nausea, and cognitive symptoms including fatigue, memory trouble, and depression. Early symptoms tend to be vague: tiredness, general weakness, muscle aches.
Secondary Hyperparathyroidism
Secondary hyperparathyroidism is a reaction, not a gland problem. When another condition drains calcium from the body, the parathyroid glands ramp up PTH production to compensate. The most common trigger is chronic kidney disease, because failing kidneys can’t activate vitamin D properly, which means your gut absorbs less calcium from food. Low vitamin D levels, intestinal diseases that impair nutrient absorption, and certain intestinal surgeries can also cause it. In secondary hyperparathyroidism, PTH is high but calcium is typically low or normal, which is the key difference from the primary form.
Tertiary Hyperparathyroidism
Tertiary hyperparathyroidism develops after the parathyroid glands have been overstimulated for so long (usually by end-stage kidney disease) that they essentially go rogue. Even after the underlying calcium problem is corrected, the glands keep overproducing PTH on their own. At this stage, both PTH and calcium are elevated, and the condition no longer responds to the medical treatments that work for secondary hyperparathyroidism.
Hypoparathyroidism: Too Little Hormone
Hypoparathyroidism is the opposite problem. The glands don’t produce enough PTH, so blood calcium drops too low. The most common cause is accidental damage to or removal of the parathyroid glands during neck surgery, particularly thyroid operations or surgery for throat and neck cancers. Autoimmune conditions can also attack the glands, and some people are born with glands that are absent or nonfunctional.
Low calcium makes nerves and muscles overly excitable, which produces a distinctive set of symptoms: tingling or burning in the fingertips, toes, and lips; muscle cramps in the legs, feet, abdomen, or face; and spasms or twitching, especially around the mouth but also in the hands, arms, and throat. Chronic hypoparathyroidism can lead to fatigue, weakness, headaches, memory difficulty, and cataracts. In children, it can interfere with normal tooth development, affecting both enamel and roots.
How Parathyroid Disorders Are Diagnosed
Diagnosis starts with two blood tests: serum calcium and intact PTH. Normal PTH falls between 11 and 51 pg/mL. The pattern of these two values together points to the type of disorder. High calcium with high PTH suggests primary hyperparathyroidism. Low calcium with high PTH points to secondary hyperparathyroidism. Low calcium with low PTH indicates hypoparathyroidism. Vitamin D levels, phosphate, and kidney function tests help round out the picture.
Once hyperparathyroidism is confirmed and surgery is being considered, imaging helps pinpoint which gland is the problem. A sestamibi scan, which uses a small amount of radioactive tracer that concentrates in overactive parathyroid tissue, has a sensitivity of about 82%. A newer technique called 4D CT scanning performs slightly better at roughly 88% sensitivity. Ultrasound is another option, picking up abnormal glands about 73% of the time. Surgeons often use a combination of these to plan their approach, especially for minimally invasive procedures where they need to know exactly which gland to target.
Treatment for Hyperparathyroidism
Surgery is the definitive treatment for primary hyperparathyroidism. The traditional approach involves exploring the neck and examining all four glands, with cure rates above 95%. Increasingly, surgeons use a minimally invasive technique through an incision smaller than 3 centimeters, targeting just the one abnormal gland. This approach, combined with a rapid PTH blood test done during surgery to confirm hormone levels are dropping, achieves cure rates as high as 99% with fewer complications. Good candidates for the minimally invasive approach are people with a single adenoma that shows up clearly on preoperative imaging. People with very large adenomas (over 3 cm), prior neck surgery, or multiple affected glands typically need the traditional exploration.
For people who can’t have surgery, medications called calcimimetics can help control the condition. These drugs make the calcium-sensing receptor on parathyroid cells more sensitive, essentially tricking the glands into thinking calcium levels are higher than they are. This lowers PTH release without actually raising calcium and phosphorus in the blood. Calcimimetics are particularly useful in secondary hyperparathyroidism from kidney disease.
Treatment for secondary hyperparathyroidism focuses on addressing the root cause: managing kidney disease, correcting vitamin D deficiency, or treating whatever condition is preventing calcium absorption. Tertiary hyperparathyroidism, because the glands no longer respond to medical management, usually requires surgery.
Treatment for Hypoparathyroidism
Hypoparathyroidism is managed by replacing what the body can no longer regulate on its own. That means calcium supplements and active vitamin D to maintain safe blood calcium levels. The goal is to keep calcium high enough to prevent symptoms like muscle spasms and tingling, while avoiding levels so high they cause kidney problems. This typically requires regular blood monitoring to adjust doses over time, since the body’s natural feedback system for calcium is no longer working.
What Untreated Parathyroid Disease Does Over Time
Left unmanaged, hyperparathyroidism slowly pulls calcium from bones, weakening them and increasing fracture risk, particularly at the spine, hip, and wrist. Kidney stones become a recurring problem because excess calcium filters through the kidneys and crystallizes. Chronic high calcium can also contribute to cardiovascular issues and persistent fatigue that chips away at quality of life. Because symptoms develop gradually and can be vague for years, many people attribute them to aging or stress rather than a treatable gland problem.
Untreated hypoparathyroidism carries its own risks. Chronically low calcium can lead to seizures, heart rhythm abnormalities, and calcium deposits in the brain and kidneys. The muscle cramping and cognitive fog that come with persistent hypocalcemia can significantly affect daily functioning. Both forms of parathyroid disease are highly manageable once identified, which is why an unexplained calcium abnormality on a routine blood panel is worth investigating further.