The diagnosis of hyperparathyroidism is made by testing blood for calcium, parathyroid hormone, creatinine, and vitamin D levels. Screening blood tests for calcium levels is routine, and can detect early hyperparathyroidism.
Once a diagnosis of primary hyperparathyroidism has been secured, a surgical consultation is advised to figure out if you need surgery or can be safely monitored without surgery. If surgery is indicated, preoperative imaging of the overactive parathyroid gland(s) should be undertaken to see if you may be a candidate for minimally invasive parathryoidectomy.
Performed easily with a probe on the neck and has no radiation. It can evaluate enlarged parathyroid glands, and also assess the thyroid at the same time.
4-D CT Scan
The “4-D” refers to the fourth dimension – which is very precise timing of the intravenous contrast and the scanning. This test is very accurate and finds parathyroid glands that may hide in uncommon areas such as high in the neck, behind the great vessels, such as the carotid, behind the esophagus, or in the chest. This test requires expertise in performing the scan properly, and interpreting it well. It requires intravenous contrast and does have radiation exposure.
A mild radioactive dye (called sestamibi) is injected into the vein and absorbed by the overactive parathyroid gland. Rotating X-ray scans identify the presence and location of the sestamibi. This test does require injection of the dye and multiple X-rays, and can sometimes be more time consuming.
MRI is not used routinely for detection of enlarged parathyroid glands, but may be recommended in select patients with previously failed operations for hyperparathyroidism when a CT scan cannot be done, as may be the case in pregnant women.
Arteriography and Venous Sampling
Usually reserved for patients who have undergone parathyroid surgery previously, but now have either recurrent or persistent hyperparathyroidism. This invasive test involves the placement of a tiny catheter in the vein and guided in the neck and upper chest in order to measure blood samples of parathyroid hormone levels at different locations. This can provide a map of where the most parathyroid hormone is found, and helps guide the surgeon to the location of the hidden parathyroid gland.