A source of false results in the intraoperative parathyroid density test.

A simple density test offering a valuable clue for the intraoperative differentiation of parathyroid hyperplasia from neoplasia has been described. According to the authors, if a sliver of parathyroid tissue taken from the central portion of a parathyroid gland does not sink in a mannitol solution of a defined specific gravity, it is normal. We have encountered a situation in which a sliver from the central position of an abnormal gland did not sink, thereby seemingly negating the test's utility. However, microscopic examination of the sliver revealed the reason it floated, and an additional sliver from near the surface of the same gland sank. Caution in choosing the appropriate portion of the gland to be tested is emphasized in order to avoid confusing false-negative results, or abandoning what has otherwise been a simple, fast, and accurate adjuvant intraoperative test in our laboratory.