Does large parathyroid adenomas increase risk of severe hypercalcemia?

(1) Background: Primary hyperparathyroidism (PHPT) is mainly caused by parathyroid adenoma (PA). Rare variants of PA, weighing >2,0-3,5g are called “large” or “giant” adenomas and account for about 1,5% of all PA. The purpose of this study was to compare normal sized and large parathyroid lesions identifying risk factors for severe hypercalcemia; (2) Methods: 27 patients with PHPT and parathyroid lesion ≥2,0cm3 (study group) were compared with 73 patients with PHPT and lesion <2,0cm3 (control group). In both groups majority were women (81,5%-study group, 90,5%-control group, gender ratios 9,4:1 and 4,4:1 respectively). The patients were examined preoperatively and postoperatively: PTH, creatine, calcium and phosphate serum and urine concentrations and calcidiol serum levels were assessed. Preoperatively ultrasonography (US) was performed. (3) Results: Patients with larger parathyroid lesions had signifficantly higher PTH and calcium serum concentration and lower serum phosphate and calcidiol concentration. There were no statistically significant differences in the concentration of creatine in serum and urine, calciuria and tubular reabsorption of phosphorus (TRP). US relatively underestimated the parathyroid volume of about 0,3-0,4ml (10% in larger lesions and 43% in smaller ones); (4) Conclusions: Due to higher PTH and calcium levels, larger parathyroid adenomas may be the higher risk of severe hypercalcemia. US underestimated in general parathyroid volume.