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Paper 19 (1100)
SURGERY FOR HYPERPARATHYROIDISM: DOES FUNCTION OR SIZE MATTER MOST?
Background: Minimally invasive parathyroidectomy has a high cure rate despite studies demonstrating that not all enlarged parathyroid glands are necessarily removed, and that the fall in IO-PTH does not necessarily predict the presence of multiple enlarged glands. The aim of this study was to compare functional characteristics, such as PTH secretion, with parathyroid gland morphology.
The 26th Annual Meeting of the American
Association of Endocrine Surgeons
April 3rd- 5th,2005 - Paradisus Riviera Cancun.
Leigh Delbridge, Ryan Mun, Margaret Wilkinson, Arthur Conigrave
University of Sydney, Sydney, Australia
Methods: PTH secretion was determined by the technique of periperfusion. Fresh parathyroid cells were loaded onto a bed of Bio-Gel P4/ Sephadex G-25 and exposed to a Ca++ gradient. PTH was measured and PTH secretion expressed as maximum secretion rate, IC50 (calcium receptor sensitivity), and percent suppression. The study was conducted in 3 phases: (1) PTH secretion in cells from 12 normal parathyroids autotransplanted at thyroid surgery was compared with 14 parathyroid adenomas; (2) in those same adenomas, functional characteristics such as PTH secretion, sestamibi uptake, serum calcium, and IO-PTH fall, were correlated with morphological characteristics such as gland weight and histology; (3) the accuracy of PTH secretion as a predictor of the sequential fall in IO-PTH was then determined in 4 patients with double parathyroid adenomas.
Results: (1) there were significant differences between normal and abnormal parathyroid tissue consistent with reduced calcium sensitivity: maximum secretion rate (mean + SD) (3.9 + 1.54 vs 2.0 + 1.40 fg/min/cell, p= 0.002), IC50 (1.1 + 0.06 vs 1.2 + 0.08 mM/L, p=0.02). However there was considerable heterogeneity within the adenomas, with some overlapping the normal range, and others exhibiting spectacular loss of calcium-dependent regulation; (2) there was no overall correlation between PTH secretion and gland morphology; (3) in 3 of 4 double adenomas removed, PTH secretion of either the first or second removed enlarged gland accurately predicted the observed fall in IO-PTH, however gland size did not correlate with IO-PTH dynamics.
Conclusions: Adenoma function as determined by PTH secretion is an accurate predictor of IO-PTH dynamics. Not all macroscopically enlarged parathyroid glands demonstrate abnormal PTH secretion.