Using X-Ray Dye to Locate Hidden Parathyroid Tumors

Study Summary

Occasionally tumors of the parathyroid gland cannot be detected by standard x-ray diagnostic procedures (CT scans, MRIs, and ultrasounds). In order for the tumor to be removed surgically it must first be localized. To do this often requires a procedure known as parathyroid arteriography and parathyroid venous sampling. This procedure begins by placing a catheter through a blood vessel in the groin. The catheter is then guided through blood vessels to reach the area of the neck. The blood vessels in this region flow in and out of the thyroid and parathyroid. An X-ray dye is then injected through the catheter into the arteries of the thyroid/parathyroid (parathyroid arteriography). The alternative is taking a small sample of the veins found in this same region (parathyroid venous sampling). Researchers prefer parathyroid arteriography because it causes less discomfort to the patient and requires less experience to do the procedure. However, parathyroid arteriography provides positive results in only 50% of patients undergoing the procedure. Parathyroid venous sampling provides greater amounts of positive results but the readings are often imprecise. Parathyroid tissue secretes a hormone known as PTH (parathyroid hormone). The release of PTH is stimulated by low levels of calcium in the blood. The idea behind the study is to inject a dye into the area of the parathyroid that will cause a release of PTH. Several parathyroid venous samplings will be taken following the abrupt elevation of PTH. This will provide information on the effectiveness of an intraarterial hypocalcemic stimulus (injection of dye into the arteries of the parathyroid when calcium blood levels are low) and venous sampling as techniques to improve localizing parathyroid tumors.