Primary hyperparathyroidism is diagnosed through blood tests. Since the parathyroid hormone (PTH) levels control the calcium levels, the two levels normally move in opposite directions. (see What do the parathyroid glands do?) For example, when the blood calcium level is high, the PTH level should be low or on the lower end of normal. When the blood calcium level is low, the PTH level should increase (in order to tell the body to absorb more calcium). In primary hyperparathyroidism, both levels are elevated. Ocasionally in patients with primary hyperparathyroidism, one or both of these levels may be normal, but in the higher end of normal (see Special Cases: Normocalcemic Hyperparathyroidism). Additional tests that may be helpful in making the diagnosis of primary hyperparathyroidism include the blood phosphate level, the vitamin D level, urine calcium levels (a urine test of calcium collected over a 24-hour period), and the blood creatinine level (a measure of kidney function). The 24 hour urine calcium level will help determine if the individual has familial hypocalciuric hypercalcemia (a benign condition not requiring surgery). Vitamin D levels should be checked because low vitamin D levels may be causing a problem called secondary hyperparathyroidism and vitamin D levels need to be cautiously replaced before further work up is done. (see Secondary Hyperparathyroidism) Patients with elevated calcium and/or parathyroid hormone levels should also have their bone density tested. This is done by a special x-ray test called a DEXA-scan.
Untreated primary hyperparathyroidism can cause a number of health problems over the long term, such as kidney stones and osteoporosis (thinning or weakening of the bones), but most often does not lead to medical emergencies. Once you have been diagnosed with primary hyperparathyroidism, the decision for treatment should be made after careful consideration with the advice of your primary care physician, endocrinologist, and/or endocrine surgeon. Prior to an operation, a series of "localizing tests" (radiology tests to determine which gland(s) are abnormal) will likely be ordered. (see Localizing Tests)