Parathyroid disease is a condition in which the parathyroid glands produce too much or too little parathyroid hormone (PTH), disrupting your body’s ability to regulate calcium levels. The most common form, primary hyperparathyroidism, affects roughly 2 in every 1,000 people. While some cases cause obvious symptoms like kidney stones and bone loss, many are discovered incidentally through routine blood work.
What the Parathyroid Glands Do
Most people have four parathyroid glands, each about the size of a grain of rice, sitting behind the thyroid gland in the neck. Their sole job is producing parathyroid hormone, which keeps blood calcium within a tight range. Calcium isn’t just about bones. It’s essential for muscle contraction, nerve signaling, and heart rhythm, so even small shifts matter.
PTH raises blood calcium through three pathways. In bone, it triggers cells called osteoclasts to break down small amounts of bone tissue, releasing stored calcium into the bloodstream. In the kidneys, it tells the body to hold onto calcium that would otherwise be lost in urine while also flushing out excess phosphorus. And it stimulates the kidneys to activate vitamin D, which in turn helps your intestines absorb more calcium from food. When calcium levels rise enough, healthy parathyroid glands dial back PTH production. When that feedback loop breaks down, parathyroid disease develops.
Primary Hyperparathyroidism
Primary hyperparathyroidism means one or more parathyroid glands are overproducing PTH on their own, independent of the body’s actual calcium needs. The hallmark lab finding is elevated PTH alongside elevated blood calcium. In 80 to 85 percent of cases, the cause is a single benign tumor called a parathyroid adenoma. Another 10 to 15 percent of cases involve enlargement of multiple glands (called multigland hyperplasia or multiple adenomas). Parathyroid cancer accounts for less than 1 percent of cases.
The classic symptoms are captured in a medical mnemonic: “stones, bones, groans, and psychic moans.” Stones refers to kidney stones, which form when excess calcium spills into the urine. Bones refers to weakened bone density and fractures, because PTH is constantly pulling calcium out of the skeleton. Groans covers abdominal complaints like constipation and nausea. Psychic moans describes the cognitive and mood effects: brain fog, depression, fatigue, and difficulty concentrating.
In practice, many people with primary hyperparathyroidism don’t have dramatic symptoms at diagnosis. Early signs tend to be vague: fatigue, general weakness, muscle aches, or constipation that’s easy to chalk up to other causes. Some patients only realize how much the disease was affecting them after treatment, when the fog lifts.
Secondary and Tertiary Hyperparathyroidism
Secondary hyperparathyroidism is a different situation. Here, the parathyroid glands are overworking because something else in the body is keeping calcium low. The two most common triggers are chronic kidney disease and vitamin D deficiency.
In chronic kidney disease, the kidneys lose the ability to clear phosphorus from the blood. High phosphorus binds to calcium and pulls levels down. At the same time, failing kidneys can no longer activate vitamin D, so less calcium gets absorbed from food. The parathyroid glands respond by pumping out more and more PTH, trying to compensate. Over time, this constant stimulation causes the glands to enlarge. Vitamin D deficiency works through a similar path: without enough active vitamin D, intestinal calcium absorption drops, and PTH rises to make up the difference.
Tertiary hyperparathyroidism develops when secondary hyperparathyroidism goes on long enough that the enlarged parathyroid glands become autonomous. They start overproducing PTH regardless of calcium levels. At this stage, both PTH and calcium are elevated (similar to primary disease), but the root cause is prolonged overstimulation, most often in patients with long-standing kidney disease. Even a kidney transplant that restores normal function may not be enough to quiet glands that have already become autonomous.
Hypoparathyroidism
Hypoparathyroidism, the underproduction of PTH, is less common but can be equally disruptive. Low PTH causes blood calcium to drop and phosphorus to rise. The most frequent cause is accidental damage to the parathyroid glands during thyroid or other neck surgeries, since the glands are tiny and sit in the same tight space. Other causes include autoimmune destruction of the glands, very low magnesium levels (which the body needs to produce PTH normally), and rare genetic conditions like DiGeorge syndrome, in which the parathyroid glands never develop.
Symptoms of low calcium can range from mild tingling in the fingertips and around the mouth to muscle cramps, spasms, and in severe cases, seizures. Some people experience anxiety, difficulty thinking clearly, or a sense of tightness in the hands and feet. Because calcium is critical for normal heart rhythm, significant drops require prompt attention.
How Parathyroid Disease Is Diagnosed
Diagnosis starts with blood tests. A PTH level paired with a serum calcium level is the cornerstone. In primary hyperparathyroidism, both are elevated. In secondary hyperparathyroidism, PTH is high but calcium is low or normal. In hypoparathyroidism, both PTH and calcium are low. Phosphorus, vitamin D, and kidney function are typically checked as well to clarify the picture.
Once primary hyperparathyroidism is confirmed, imaging helps locate the abnormal gland before surgery. Ultrasound is often the first step because it’s noninvasive and widely available. A sestamibi scan, which uses a small amount of radioactive tracer that gets absorbed preferentially by overactive parathyroid tissue, is another standard tool. For single adenomas, a specialized CT scan called 4D-CT has shown higher sensitivity than sestamibi (85 percent versus 65 percent), though sestamibi has very high specificity at 98 percent. For multigland disease, both imaging methods are less reliable, with 4D-CT detecting about 55 percent of cases and sestamibi around 25 percent.
Treatment for Hyperparathyroidism
Surgery is the only cure for primary hyperparathyroidism. A surgeon removes the overactive gland or glands, and in experienced hands the success rate is above 95 percent. Many centers now perform a minimally invasive procedure through a small neck incision, often under light sedation, with patients going home the same day.
Not everyone with primary hyperparathyroidism needs immediate surgery. If your calcium is only mildly elevated and you have no symptoms, your doctor may recommend monitoring. However, international guidelines identify several situations where surgery is advised even without symptoms: if calcium is more than 1.0 mg/dL above the upper limit of normal, if bone density scores fall to a T-score of negative 2.5 or below (indicating osteoporosis), if you’ve already had a fragility fracture, if kidney function has declined below a certain threshold, if you have kidney stones or calcium deposits in the kidneys, or if you’re younger than 50. Meeting just one of these criteria is enough to tip the recommendation toward surgery.
For people who can’t have surgery or choose not to, a class of medication called calcimimetics can help. These drugs trick the parathyroid glands into sensing more calcium than is actually present, which reduces PTH secretion and lowers blood calcium. They don’t cure the underlying disease but can keep calcium levels in a safer range.
Secondary hyperparathyroidism is treated by addressing its root cause. That means correcting vitamin D deficiency with supplements, managing phosphorus levels through diet and medications that bind phosphorus in the gut, and optimizing kidney disease treatment. Calcimimetics are also used in patients on dialysis whose PTH remains stubbornly high despite other measures. Tertiary hyperparathyroidism, because the glands have become autonomous, often requires surgery to remove most or all of the enlarged parathyroid tissue.
Treatment for Hypoparathyroidism
Hypoparathyroidism is managed with calcium supplements and active vitamin D to replace what the body can no longer regulate on its own. The goal is to keep calcium in the low-normal range, high enough to prevent symptoms but not so high that excess calcium damages the kidneys. This requires regular blood and urine monitoring, especially early on, to fine-tune doses. Some patients find their levels fluctuate and need ongoing adjustments.
Living With Parathyroid Disease
For most people with primary hyperparathyroidism, surgery resolves the problem permanently. Bone density often improves within the first year or two after a successful operation, and kidney stone risk drops significantly. Many patients report that symptoms they didn’t even fully recognize, like fatigue, poor sleep, and mental sluggishness, improve noticeably after surgery.
If you’re being monitored rather than treated surgically, regular blood tests and periodic bone density scans are important to catch progression early. Staying well-hydrated helps reduce kidney stone risk. For those with hypoparathyroidism, the condition is usually lifelong but manageable, requiring consistent medication and periodic lab checks to keep calcium stable.