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Original Investigation
July 29, 2020

Analysis of Primary Hyperparathyroidism Screening Among US Veterans With Kidney Stones

Author Affiliations
  • 1Division of Nephrology, Department of Medicine, Stanford University School of Medicine, Palo Alto, California
  • 2Division of Nephrology, Department of Urology, Veterans Affairs Palo Alto Health Care System, Palo Alto, California
  • 3Department of Urology, Stanford University School of Medicine, Palo Alto, California
  • 4Department of Surgery, Stanford University School of Medicine, Palo Alto, California
  • 5Department of Urology, Santa Clara Valley Medical Center, San Jose, California
  • 6Department of Epidemiology and Population Health, Stanford University School of Medicine, Palo Alto, California
JAMA Surg. 2020;155(9):861-868. doi:10.1001/jamasurg.2020.2423
Key Points

Question  What proportion of patients with kidney stones are screened for primary hyperparathyroidism in clinical practice?

Findings  In this cohort study of 7561 veterans with kidney stones and hypercalcemia who received care in Veterans Health Administration facilities, only 25% completed a serum parathyroid hormone level measurement around the time of their initial stone diagnosis.

Meaning  Findings of this study suggest that improving the rates of screening for primary hyperparathyroidism in patients with kidney stones could increase the rates of detection and treatment of primary hyperparathyroidism and decrease recurrent stone disease.

Abstract

Importance  Approximately 3% to 5% of patients with kidney stones have primary hyperparathyroidism (PHPT), a treatable cause of recurrent stones. However, the rate of screening for PHPT in patients with kidney stones remains unknown.

Objectives  To estimate the prevalence of parathyroid hormone (PTH) testing in veterans with kidney stones and hypercalcemia and to identify the demographic, geographic, and clinical characteristics of veterans who were more or less likely to receive PTH testing.

Design, Setting, and Participants  This cohort study obtained Veterans Health Administration (VHA) health records from the Corporate Data Warehouse for veterans who received care in 1 of the 130 VHA facilities across the United States from January 1, 2008, through December 31, 2013. Historical encounters, medical codes, and laboratory data were assessed. Included patients had diagnostic or procedural codes for kidney or ureteral stones, and excluded patients were those with a previous serum PTH level measurement. Data were collected from January 1, 2006, to December 31, 2014. Data analysis was conducted from June 1, 2019, to January 31, 2020.

Exposures  Elevated serum calcium concentration measurement between 6 months before and 6 months after kidney stone diagnosis.

Main Outcomes and Measures  Proportion of patients with a serum PTH level measurement and proportion of patients with biochemical evidence of PHPT who underwent parathyroidectomy.

Results  The final cohort comprised 7561 patients with kidney stones and hypercalcemia and a mean (SD) age of 64.3 (12.3) years. Of these patients, 7139 were men (94.4%) and 5673 were white individuals (75.0%). The proportion of patients who completed a serum PTH level measurement was 24.8% (1873 of 7561). Across the 130 VHA facilities included in the study, testing rates ranged from 4% to 57%. The factors associated with PTH testing included the magnitude of calcium concentration elevation (odds ratio [OR], 1.07 per 0.1 mg/dL >10.5 mg/dL; 95% CI, 1.05-1.08) and the number of elevated serum calcium concentration measurements (OR, 1.08 per measurement >10.5 mg/dL; 95% CI, 1.06-1.10) as well as visits to both a nephrologist and a urologist (OR, 6.57; 95% CI, 5.33-8.10) or an endocrinologist (OR, 4.93; 95% CI, 4.11-5.93). Of the 717 patients with biochemical evidence of PHPT, 189 (26.4%) underwent parathyroidectomy within 2 years of a stone diagnosis.

Conclusions and Relevance  This cohort study found that only 1 in 4 patients with kidney stones and hypercalcemia were tested for PHPT in VHA facilities and that testing rates varied widely across these facilities. These findings suggest that raising clinician awareness to PHPT screening indications may improve evaluation for parathyroidectomy, increase the rates of detection and treatment of PHPT, and decrease recurrent kidney stone disease.

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