Introduction: It is difficult to differentiate benign and malignant lesions just by histopathological evaluation due to lack of clear criteria of diagnosis. Moreover, the group of benign pathologies of parathyroids is not homogenous, and recurrence of symptoms of hyperparathyroidism after surgical management was also noted in this group. This complication is not always due to inappropriate surgical technique. The goal of this work was to find the relationship between cellular ploidy and proliferative activity of adenomas and hyperplasia of parathyroids and preoperative levels of calcium and parathormone in the serum of patients surgically treated for primary hyperparathyroidism.

Material and methods: A total of 98 parathyroid glands were tested, of which 81 (82.7%) were from female patients and 17 (17.3%) from male; the age of the patients was from 22 to 82 years, with an average of 58 years.

Results: In resected glands pathological evaluation showed the following results: in 53 (54.1%) adenoma was present, and in 45 (45.9%) there was hyperplasia. Sixty-seven of the samples (68.4%) were characterised as diploid and 31 (31.6%) as aneuploid. There is important positive correlation (r = 0.34595; p = 0.011) between the percentage of S-phase cells (% SPF) and calcium levels measured prior to surgical resection of adenoma. The further analysis of patients with adenoma characterised by aneuploidy proved a statistically valid, positive correlation between %SPF and ionised calcium levels in blood serum of patients both before (r = 0.7189; p = 0.003) and after the surgical treatment (r = 0.6313; p = 0.012).

Conclusions: 1. Benign lesions of parathyroid with ploidy indicates their heterogeneity. 2. In aneuploid benign adenomas of parathyroid glands an increased percentage of cells in S phase (% SPF) correlates with a high level of calcium in serum pre- and post-parathyroidectomy.