Predictors of Single Adenoma versus Four Gland Disease in Normohormonal Patients with Parathyroid-Induced Hypercalcemia

Abstract

Objectives:

1) Examine differences in spatial measurements of parathyroid glands in normohormonal patients with parathyroid-related hypercalcemia. 2) Determine a predictive value to stratify which patients will require single- or four-gland surgery.

Methods:

A retrospective chart review was conducted of parathyroidectomy patients from 2008-2011 at our tertiary care institution. Patients with parathyroid hormone levels < 65 pg/ml were included and divided into single adenoma (SA) or four gland surgery (FGS). Exclusion criteria included diagnoses of secondary or tertiary hyperparathyroidism. Preoperative ultrasound measurement (cm), intraoperative gland weight (g), and intraoperative parathyroid hormone (iPTH) were recorded and used to calculate gland volume (cm3) and density (g/cm3). Significant differences between groups were examined with the student t-test (P < 0.05).

Results:

24 patients were included, 18 (75%) with SA and 6 (25%) with FGS. There was no significant difference in age or gender between included patients and those with elevated PTH levels. SA patients were significantly more likely to have larger maximum ultrasound measurements, larger gland volume, weight and density, and greater iPTH values than patients with FGS. Of the spatial measurements collected, a cut-off density of < 0.3 g/cm3 was 100% specific and sensitive for predicting patients who required FGE surgery. Positive predictive value was 100%.

Conclusions:

Normohormonal patients with hypercalcemia have a higher incidence of four gland disease than those with elevated PTH levels. Regardless, single adenomas can be found in these patients. Pre-operative ultrasound and intraoperative calculation of gland density are easily done and may be an alternative to iPTH for surgical decision making.