NEPHROLITHIASIS IN PRIMARY HYPERPARATHYROIDISM: A COMPARISON BETWEEN SILENT AND SYMPTOMATIC PATIENTS

Objective: To characterize primary hyperparathyroidism (PHPT) patients with renal stones and to compare silent with symptomatic stone formers. Methods: We reviewed clinical data from 234 patients with PHPT, comparing those with and without renal stones (n = 109 and 125, respectively), and among stone formers those symptomatic versus silent ( n = 93 and 16, respectively). Results: Stone formers were younger, had higher urinary calcium levels and higher estimated glomerular filtration rates (eGFRs) compared to patients without stones. Patients with silent stones had higher parathyroid hormone (PTH) and lower 25OH-vitamin D (25OHD) levels and more frequently experienced microlithiasis than patients with symptomatic renal stones. Conclusion: Nephrolithiasis is a common complication of PHPT. Most patients with silent renal stones have microlithiasis, associated to some features of more severe disease. Lower 25OHD levels in silent stone formers raise the hypothesis that vitamin D status can influence the clinical expression of nephrolithiasis in PHPT patients.