By: Samuel K Snyder, M.D., F.A.C.S.
Chief of Endocrine Surgery, DHR Diabetes and Endocrinology Institute
If this test result has occurred outside the hospital through your doctor’s office, there is a high likelihood that you have parathyroid gland disease. There are several causes of hypercalcemia, but the most common one is primary hyperparathyroidism. Four small pea-size parathyroid glands make parathyroid hormone, which controls the blood calcium level. “Para” means “next to” and that is what parathyroid glands are anatomically. They are typically located on the backside of the thyroid gland, 2 on each side, upper and lower parathyroid glands. Parathyroid hormone increases the blood calcium by removing calcium from bone, increasing calcium absorption from the intestine, and reducing calcium excretion in the kidneys. If the blood calcium is elevated, then the parathyroid hormone level should be appropriately low. When an individual has primary hyperparathyroidism, the parathyroid hormone level is inappropriately elevated or high normal in the face of elevated blood calcium. If the first check of the blood parathyroid hormone level is inappropriately high, then the diagnosis of primary hyperparathyroidism is established.
The cause of primary hyperparathyroidism is unknown, but individuals with this disease invariably have low blood vitamin-D levels. Vitamin-D helps with absorption of calcium from the intestine, so a deficiency of it can lead to relatively low blood calcium that requires more parathyroid hormone secretion to keep the calcium normal. Individuals with low vitamin-D levels frequently have elevated parathyroid hormone levels. Correcting this deficiency can lower the parathyroid hormone level to normal, if the blood calcium is also normal. Vitamin-D deficiency is very prevalent in the Rio Grande Valley so it is wise to check the vitamin-D blood level, particularly with primary hyperparathyroidism.
Primary hyperparathyroidism is typically caused by a single benign parathyroid tumor in 1 of the 4 glands. The tumor secretes excessive parathyroid hormone. This can lead to complications over time with high urine calcium, causing kidney stones/damage or leaching of calcium from bones to cause osteoporosis. Calcium is important for normal nerve and muscle function, so patients with high calcium may have symptoms of fatigue, or difficulty with memory and concentration. The location of the parathyroid tumor can be determined by neck ultrasound, a nuclear medicine scan with technetium sestamibi that gets picked up by a parathyroid tumor preferentially, or a special 4D-CT x-ray with timed intravenous contrast to localize the hypervascular parathyroid tumor.
Once the location of the parathyroid tumor is determined, a minimally-invasive approach to parathyroid surgery can be used. Technetium sestamibi can be injected just prior to surgery to allow using a Geiger counter device to guide surgery. The half-life of parathyroid hormone is 3 to 5 minutes. The parathyroid hormone blood level is checked 5 and 10 minutes after removing the parathyroid tumor. A marked reduction in the parathyroid hormone level confirms that the primary hyperparathyroidism is corrected and surgery can be minimized and done as an outpatient procedure. Options to surgery include just monitoring the severity of the disease or when the risk of surgery is high, giving calcimimetic medication to try to reduce the parathyroid hormone level.