Background
Hypercalcemic crisis (HC) is a potentially life-threatening manifestation of primary hyperparathyroidism (PHPT). This study aims to identify patients with PHPT at greatest risk for developing HC.
Methods
This retrospective cohort study included patients with a pre-operative calcium of at least 12mg/dL undergoing initial parathyroidectomy for PHPT from 11/2000–03/2016. We compared those with HC, defined as needing hospitalization for hypercalcemia, to those without HC.
Results
The study cohort included 29(15.8%) with HC and 154(84.2%) without. Demographics and comorbidities were similar between groups. Patients with HC were more likely to have a history of kidney stones (31.0% vs. 14.3%, P=0.039), higher pre-operative calcium (median 13.8 vs. 12.4mg/dL, P<0.001), higher parathyroid hormone (PTH) (median 318 vs. 160pg/mL, P=0.001), and lower vitamin D (median 16 vs. 26ng/mL, P<0.001) than patients without HC. Cure rates with parathyroidectomy were similar, but nearly double the proportion of patients with HC had multi-gland disease (24.1 vs. 12.3%, P=0.12). In multivariable analysis, higher pre-operative calcium (OR 1.7, 95% CI 1.1–2.5), higher PTH (OR 1.0, 95% CI 1.0–1.0), and kidney stones (OR 3.0, 95% CI 1.1–8.2) were independently associated with HC. A Classification and Regression Tree revealed that 91% of patients with a calcium ≥13.25 mg/dL and a Charlson Comorbidity Index ≥4 developed HC.
Conclusions
These data indicate that calcium, PTH, and kidney stones are important in predicting who is at greatest risk of HC. The Classification and Regression Tree can further help stratify risk for developing HC and allow surgeons to expedite parathyroidectomy accordingly.