Diagnosing Hyperparathyroidism

NYU Langone endocrinologists can quickly diagnose the specific type of hyperparathyroidism. This condition is characterized by an inappropriately high level of parathyroid hormone production from one or more of the four parathyroid glands. These glands, each normally about the size of a lentil, are located behind the thyroid gland in the neck.

Parathyroid hormone controls calcium levels in the body by regulating the release of calcium from bone, the absorption of calcium from the intestines, and the excretion of calcium from the kidneys into the urine.

The parathyroid glands also control the activation of vitamin D in the kidneys. The body obtains vitamin D from food or sunlight, and then the kidneys convert it into an active form that helps the body to absorb calcium and form strong bones.

If your parathyroid glands secrete too much parathyroid hormone, calcium levels in the blood rise, leading to a condition called hypercalcemia. People with mild hypercalcemia usually don’t have symptoms. Those with more significant hypercalcemia may experience cognitive impairment, constipation, bone and joint pain, excessive urination and thirst, and malaise.

Excess parathyroid hormone can also lead to more serious conditions, such as kidney stones, permanent kidney damage, and osteoporosis.

The three types of hyperparathyroidism—primary, secondary, and tertiary—result from different causes.

Primary Hyperparathyroidism

The most common form of the condition is hyperparathyroidism due to the presence of an adenoma, or a benign tumor, in one of the parathyroid glands. It’s usually referred to as primary hyperparathyroidism.

In the majority of people with hyperparathyroidism, the disease occurs without a known cause. In a small percentage of people with hyperparathyroidism, it’s associated with an inherited disorder or another condition.

For example, inherited forms of hyperparathyroidism may be due to a rare condition known as multiple endocrine neoplasia syndrome. In people with this genetic disorder, one or more of the parathyroid glands are overactive. Tumors, or growths, may also appear on the affected glands.

In a small percentage of people with hyperparathyroidism, the parathyroid glands become overactive due to long-standing kidney failure.

The vast majority of overactive or enlarged parathyroid tumors are benign, or noncancerous. Parathyroid cancer is extremely rare and can cause severe primary hyperparathyroidism, with marked elevation of parathyroid hormone and blood calcium levels. A large or visible neck mass may also be present in people with advanced parathyroid cancer.

Secondary Hyperparathyroidism

Secondary hyperparathyroidism occurs when the parathyroid glands secrete too much parathyroid hormone in response to low calcium and vitamin D levels in the blood.

Low calcium levels can result when the body lacks vitamin D, which is necessary for the absorption of calcium from the gastrointestinal tract. Kidney disease can also lead to low calcium levels and elevated parathyroid hormone levels because it prevents the kidneys from activating vitamin D.

Doctors prescribe vitamin D supplements for people with secondary hyperparathyroidism due to vitamin D deficiency. People with secondary hyperparathyroidism due to kidney disease may be treated with vitamin D supplements and, occasionally, medication.

Tertiary Hyperparathyroidism

In tertiary hyperparathyroidism, parathyroid hormone is produced in excessive and uncontrolled amounts. This condition often occurs in people with advanced chronic kidney disease. Many of these people have long-term secondary hyperparathyroidism that has caused the parathyroid glands to reach a point where they produce too much parathyroid hormone, regardless of the body's calcium levels.

This condition leads to severely elevated calcium levels. It often requires treatment with surgery.

Diagnosing Hyperparathyroidism

Your doctor performs a physical exam and several tests to diagnose and determine the cause of hyperparathyroidism. Because secondary and tertiary forms commonly result from other conditions, your doctor may ask about any other medical issues you’re experiencing.

Blood tests are very effective in determining the type of hyperparathyroidism. Your doctor may order tests that measure calcium, parathyroid hormone, and vitamin D levels.

Kidney function tests can help doctors assess how well the kidneys are working. These can also reveal if any dysfunction is causing the excessive production of parathyroid hormone. The results of these tests help your doctor to diagnose the specific type of hyperparathyroidism and determine the best treatment.

Your endocrinologist may order one of several studies to identify the overactive parathyroid gland, particularly if surgery may be indicated.