Evaluation for Primary Hyperparathyroidism in Patients Who Present With Nephrolithiasis

Background: The incidence of primary hyperparathyroidism (PHP) is likely underestimated. Nephrolithiasis may indicate PHP with indication for parathyroidectomy. We sought to determine the proportion of patients with an index diagnosis of nephrolithiasis that have serum calcium levels measured, parathyroid hormone (PTH) levels measured if hypercalcemic, and time to referral for definitive management if PHP is diagnosed. Methods: A single-institution retrospective review was performed of adult patients presenting with nephrolithiasis between July 1, 2016 and December 31, 2018. Exclusion criteria included currently admitted patients, prior nephrolithiasis, congenital or acquired urinary tract anomalies, and patients on calciuretics. Records were assessed for serum calcium and PTH measurement, as well as referrals. Univariate statistical analysis was performed. Results: Of 1782 patients with nephrolithiasis screened, 968 met inclusion criteria. Patients were 49.8% female, 88.9% white. Mean age was 53 y. Within this cohort, 620 (64.0%) patients had a calcium measured, with a mean elapsed time from presentation of 27 d (interquartile range [IQR] 0-8). Twelve patients (1.58%) with calcium measured were hypercalcemic and eight (66.7%) had PTH measured with a mean elapsed time from presentation of 183 d (IQR 72-310), all had elevated or non-suppressed PTH. Five (62.5%) were referred to surgeons with mean elapsed referral time of 270 d (IQR 95-492). Conclusions: Many with index nephrolithiasis are not assessed for hypercalcemia or hyperparathyroidism. Patients with serum calcium and PTH values indicating PHP diagnosis may have significant delay to parathyroidectomy. Targeted interventions with electronic health record alerts or automated reflex testing may improve care in this domain.