Parathyroid gland neoplasms with irregular hormone activity (a series of clinical cases)

Primary hyperparathyroidism is an endocrine disorder characterized by excessive secretion of parathyroid hormone accompanied by upper-normal or elevated serum calcium levels resulting from primary parathyroid gland pathology. The diagnosis of primary hyperparathyroidism is established exclusively based on laboratory findings. However, the 2025 Russian Clinical Guidelines for the Management of Primary Hyperparathyroidism mention another form of the hypercalcemic variant of this condition, which may manifest as hypercalcemia combined with high-normal parathyroid hormone levels (falling within the upper limit of the reference range without exceeding it). A detailed description of this form of the disease is not provided, and in clinical practice, differential diagnosis with familial hypocalciuric hypercalcemia is recommended. Furthermore, the pathogenesis of this variant of primary hyperparathyroidism remains unclear and contradicts the classical understanding of the disease progression. Consequently, most specialists interpret hypercalcemia with normal parathyroid hormone levels as a laboratory error rather than a manifestation of primary hyperparathyroidism. In the literature, reports of primary hyperparathyroidism with normal parathyroid hormone levels are rare and largely limited to isolated case reports.

The article presents three clinical cases of diagnosis and treatment of parathyroid neoplasms with irregular hormonal activity. It is described that, despite the presence of hypercalcemia, visualization of parathyroid tumors, and high parathyroid hormone levels in the needle washings, normoparathyremia was observed in patients over a long period. In all cases, the diagnosis was verified by histological examination.