Features to differentiate parathyroid adenoma from hyperplasia would include which of the following -

Parathyroid adenoma can be differentiated from hyperplasia only at the time of surgery. In the case of adenoma, only one gland is found to be enlarged the other three are normal or atrophic. In hyperplasia, all four glands are diffusely enlarged. Some recent techniques such as 99mTc sestamibi scan are now able to localize and differentiate adenoma from hyperplasia, preoperatively.