Using X-Ray Dye to Locate Hidden Parathyroid Tumors
Using X-Ray Dye to Locate Hidden Parathyroid Tumors
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.
Although noninvasive diagnostic studies [ultrasound (US), computed tomography (CT), sestamibi
 scanning, magnetic resonance imaging (MRI)] detect parathyroid pathology in one-half the
 patients referred to NIH with recurrent or persistent hyperparathyroidism (1), the invasive
 studies (direct aspiration for PTH, arteriography, venous sampling) must be performed in the
 remaining patients to provide definitive preoperative localization (2). Arteriography is
 positive in less than half the patients who must then proceed to parathyroid venous sampling,
 a technique requiring broad experience and yielding positive, but imprecise results as
 regards localization. The abrupt lowering of calcium in blood perfusing a parathyroid adenoma
 should stimulate the release of PTH which could be detected by simultaneous venous sampling.
 This principle, the intraarterial injection of a secretagogue with subsequent sampling for
 released hormone, has been applied successfully in the localization of insulinomas (3) and
 gastrinomas (4). In fact, portal venous sampling is no longer performed in this group of
 patients, having been completely replaced by the intraarterial injection of secretin or
 calcium as appropriate secretagogues for gastrin and insulin.

 Since release of PTH from parathyroid adenomas is stimulated by hypocalcemic perfusions, we
 propose to perform serial venous sampling from a catheter positioned in the SVC to detect
 abrupt elevations of PTH following the injection of contrast agent into each of the vessels
 selectively catheterized at the time of parathyroid arteriography (superior thyroid arteries,
 thyrocervical trunks, internal mammary arteries). Samples from the SVC catheter will be
 obtained at 20 second intervals up to one minute and in some patients simultaneous peripheral
 samples. An elevation of parathyroid hormone 1.5 times above the baseline will be considered
 diagnostic. This technique will be applied routinely at each injection of standard
 parathyroid arteriography even in the absence of an angiographically-visualized adenoma: an
 elevation of PTH will provide localizing information comparable to venous sampling. In
 addition, when any of the imaging studies suggest that a particular anatomic site is the
 likely location of the patient's adenoma, sodium citrate, a calcium chelating agent, will be
 injected into the artery supplying this region. Blood samples will be obtained in similar
 fashion to those samples taken with contrast injections to measure PTH release following
 sodium citrate injection and determine whether this is a more effective hypocalcemic
 stimulant.
INCLUSION CRITERIA:

 Patients over the age of 2 who are enrolled in 91-DK-0085, "Studies of Hyperparathyroidism
 and Related Disorders", or patients who are undergoing parathyroid localization as part of
 routine patient care while enrolled in other Clinical protocols will be considered for the
 study.

 EXCLUSION CRITERIA:

 Patients will be excluded if:

 There is any contraindication to arteriography.

 The Patient is pregnant.