Four cases in our clinical experience of primary hyperparathyroidism are reported. All four cases were diagnosed as adenoma histologically. Computerized tomography (CT)was useful for the diagnosis of the location of the tumor. The minimum diameter of the adenoma identified by CT was 1.4 cm. There was one case in which the tumor was not identified by CT, but was found by catheter venous sampling of parathyroid hormone (PTH). The adenomas in all four cases were located in the lower glands. The removed tumors were all oval, their surface smooth, and color mostly dark red. In all cases, the serum calcium level before the operation was abnormally high. However, the level decreased immediately after the operation, and then gradually increased and eventually reached the normal value. In all cases the serum phosphorus level was abnormally low before the operation. However, immediately after the operation the level decreased, and then gradually increased and finally reached the normal value. The PTHN and PTHc of peripheral vein blood before operation showed a normal value and were not useful. However, the PTHN and PTHc of catheter venous sampling were very useful. PTHN using the ratio of catheter venous sampling to peripheral venous blood seemed to be more useful than PTHc in the diagnosis of an abnormal parathyroid gland with hyperparathyroidism.
