Frequency of Parathyroid Hormone Assessment in the Evaluation of Hypercalcemia. A Comparison Between Patients With and Without a History of Malignancy in a 20-year Dataset of 20,954 Patients.

Background: The purpose of this study was to evaluate whether a prior diagnosis of malignancy affected the assessment of parathyroid hormone (PTH) in hypercalcemic patients and whether the rate of this assessment changed over time. Methods: A retrospective cohort study was designed that included adult patients with hypercalcemia with and without a history of malignancy between January 1, 2000 and December 31, 2019 in the Marshfield Clinic Health System (MCHS). The overall and annual rates of PTH assessment in each group was determined. In patients with a PTH assessment, duration of time and number of elevated serum calcium levels between the first documentation of hypercalcemia and the assessment of PTH were recorded, as was the degree of hypercalcemia. Results: Approximately a quarter (23%) of the patients in each group had a PTH assessment. The rate of PTH assessment initially increased over time but later declined significantly. Although a more severe degree of hypercalcemia predicted a greater probability of PTH assessment, the rate of assessment declined with all degrees of hypercalcemia in the last 5 years. While most patients who had a PTH assessed did so within a few months of the first documentation of hypercalcemia, less than half (40%) had a delay of more than 2 years before a PTH level was drawn. Conclusion: This lack of appropriate and timely assessment may have significant health consequences in both groups of patients. Better education of providers about the appropriate and timely assessment of PTH in the evaluation of hypercalcemia is urgently needed.