Endocrine Abstracts

Introduction: Primary hyperparathyroidism (PHPT) is one of the most common causes of non-neoplastic hypercalcemia with characteristically increased or inappropriately normal plasma parathyroid hormone (PTH) levels. Hypercalcemia is also a significant feature of patients with multiple myeloma (MM), and a pathogenetic link is presumed between the two diseases, strengthened by preclinical data. Only limited number of case reports of concomitant PHPT and MM are available in the literature.

Case report: A 58-year-old male patient was referred to the Department of Endocrinology, University of Debrecen, in 2022 with fatigue and hypercalcemia. His PTH was in the normal range and a 15×7 mm lesion was depicted by ultrasound in the region of left parathyroid gland. Imaging with technetium 99m-pertechnetate/technetium 99m-MIBI subtraction scintigraphy and with single photon emission tomography affirmed the suspected localization of parathyroid adenoma, PTH level became slightly elevated. After the surgical removal of the parathyroid adenoma histology affirmed benign lesion, and hypercalcemia persisted accompanied by normal PTH (se calcium 2.95 mmol/l, PTH 2.4 pmol/l). Nuclear imaging was repeated, and the results excluded the existence of another parathyroid adenoma, therefore we started to evaluate the opportunity of a concomitant neoplasia. Hyperproteinemia was also detected, and hematology workup started which confirmed the diagnosis of first stage IgG-kappa type multiple myeloma without typical lytic bone lesions. Since there is increasing evidence that monoclonal gammopathies are more common in patients with PHPT, a search for multiple underlying causes of uncontrollable hypercalcemia should be performed.