Abstract and Introduction
Abstract
Context: Hypercalcemia of malignancy (HCM) has not been studied in a fashion to determine all possible mechanisms of hypercalcemia in any given patient.
Objective: The 2 objectives were to assess the completeness of evaluation and to determine the distribution of etiologies of HCM in a contemporary cohort of patients.
Methods: A retrospective analysis was performed of patients with cancer who developed hypercalcemia over 20 years at a single health system. Laboratory data were electronically captured from medical records to identify cases of parathyroid hormone (PTH)-independent hypercalcemia. The records were then manually reviewed to confirm the diagnosis of HCM, document the extent of evaluation, and determine underlying etiology(ies) of HCM in each patient.
Results:The initial data set included 167 551 adult patients with malignancy, of which 11 589 developed hypercalcemia. Of these, only a quarter (25.4%) had assessment of PTH with a third of the latter (30.9%) indicating PTH-independent hypercalcemia. Of those with PTH-independent hypercalcemia, a third (31.6%) had assessment of PTH-related peptide (PTHrP) and/or 1,25-dihydroxy (1,25-OH) vitamin D and constituted the 153 cases of HCM examined in this study. Eighty-three of these patients had an incomplete evaluation of their HCM. The distribution of etiologies of HCM was therefore determined from the remaining 70 patients who had assessment of all 3 possible etiologies (PTHrP, 1,25-OH vitamin D, and skeletal imaging) and was as follows: PTHrP, 27%; osteolytic metastases, 50%; and 1,25-OH vitamin D, 39%, with combinations of etiologies being common (approximately 20%).
