Parathyroid Disease
Anatomy and Physiology
There are four parathyroid glands located just behind the thyroid gland in the neck. Each round gland is normally less than ¼ inch long and weighs 25 – 35 mg. The glands produce parathyroid hormone (PTH) which regulates the calcium level in the body.
Primary Hyperparathyroidism
Primary hyperparathyroidism is generally caused by a benign adenoma involving one of the four parathyroid glands of the neck. Occasionally, it is caused by a benign adenoma of two glands or abnormal growth of all four glands. Parathyroid carcinoma is an extremely rare cause of hyperparathyroidism. The benign adenoma produces too much parathyroid hormone (PTH). This results in an elevated calcium level. The degree of the elevation can be mild to severe. However, symptoms do not always correlate with the level of the calcium in the blood.
These symptoms can include fatigue, muscle weakness, kidney stones, decreased memory, psychiatric problems, body aches, loss of bone strength, and broken bones. Often these symptoms can be quite subtle.
Secondary and Tertiary Hyperparathyroidism Secondary hyperparathyroidism occurs when external factors stimulate the parathyroid gland to secrete parathyroid hormone to the point where it develops hyperplastic overgrowth. This is most commonly seen in chronic renal failure. Tertiary hyperparathyroidism occurs after secondary hyperparathyroidism when the external factor is corrected but the parathyroid glands remain hyperplastic.
Parathyroid Surgery
The only treatment of an overgrown parathyroid gland is surgical removal. The operation requires a small incision over the base of the neck, and may require an overnight stay in the hospital. Frequently, the parathyroid adenoma can be identified before surgery with a nuclear medicine scan (sestamibi-scan). This can aid the surgeons to focus their exploration for the abnormal gland. Recent advances in monitoring the PTH level during surgery allow these procedures to be done with local anesthesia and some mild sedation. A radio-guided probe can also be used to aid the localization of the abnormal gland. This procedure is known as Minimally Invasive Parathyroid Surgery (MIP) with intraoperative PTH monitoring. These new techniques enable the surgeon to focus on the one abnormal gland, to avoid exploration of all the glands. Usually these patients can be discharged the afternoon of their operation.
