Primary Hyperparathyroidism

Abstract

Thirty-nine patients with primary hyperparathyroidism were studied four to eight years after their initial operation. In six patients, both the pathologist and surgeon agreed on the diagnosis of solitary adenoma; in 16 patients, the surgeon diagnosed solitary adenoma and the pathologist parathyroid hyperplasia (microscopic hyperplasia). In 16 patients, primary chief cell hyperplasia was agreed upon by the pathologist and surgeon. In the 16 patients with microscopic hyperplasia, there have been no long-term recurrences of hypercalcemia, but, in two patients, plasma parathyroid hormone levels are high. Parathyroid hormone--total calcium regression curves demonstrate significant preoperative correlation in solitary adenoma, p less than 0.01, and primary chief cell hyperplasia, p less than 0.05. After operation, significant correlations were not found between parathyroid hormone and total calcium. T-testing slope differences of pre- and postoperative parathyroid hormone--total calcium regression curves demonstrates a significant (p less than 0.01) shift to the right of the microscopic hyperplasia patients after operation, moving them to a broader range of total calcium per picogram parathyroid hormone. We conclude that 1) in primary hyperparathyroidism, positive regulation of total calcium by autonomously released parathyroid hormone exists in patients with solitary adenoma and chief cell hyperplasia; 2) autonomously functioning parathyroid tissue has been removed by operation for solitary adenoma with coexistent microscopic parathyroid hyperplasia. In this four- to eight-year follow-up period, it is clear that microscopic parathyroid hyperplasia is not associated with recurrent hypercalcemia. Two functionally distinct forms of parathyroid suppression are suggested; positively regulated microscopic hyperplasia and negatively regulated pathologically suppressed glands.

Postoperative Elevated Serum Levels of Intact Parathyroid Hormone after Surgery for Parathyroid Adenoma: Sign of Bone Remineralization and Decreased Calcium Absorption

“…Microscopic hyperplasia was previously demonstrated in the remaining parathyroid glands after surgery for a single adenoma [16]. Thus the possibility of persistent HPT as a cause of the elevated postoperative PTH levels must be considered.…”

Is focused parathyroidectomy appropriate for patients with primary hyperparathyroidism?

“…In addition, some groups have reported that microscopically hyperplastic glands of normal size are of no clinical significance and that the removal of such glands is unnecessary [ 23 ]. After experienced surgeons inspected ambiguous parathyroid lesions in patients with MGD and double adenoma, they decided whether a frozen biopsy should be performed.…”

“…In some cases, intraoperative PTH monitoring is thought to confuse the decision-making process [ 27 30 ]. Furthermore, undetected hyperplastic glands of normal size in the preoperative imaging study are of no clinical significance, and the removal of such glands is unnecessary [ 23 ].…”

Double Parathyroid Adenoma, a Clinically Nondistinct Entity of Primary Hyperparathyroidism

“…The involved parathyroid cells express more or less distinct phenotypic abnormalities in support of the association of morphology and function [5], which includes such functional characteristics as calcium receptor expression and parathyroid hormone immunoreactivity [6 -8]. Microscopic foci of morphologically abnormal parathyroid cells nevertheless must be assumed to be consistent with the absence of a clinically overt parathyroid disorder [9,10].…”