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

ABSTRACT

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. ABBREVIATIONS BMI = body mass index Ca = serum total calcium DM = diabetes mellitus eGFR = estimated glomerular filtration rate HOMA-IR = Homeostasis Model Assessment-Insulin Resistance 25OHD = 25OH-vitamin D PHPT = primary hyperparathyroidism PTH = parathyroid hormone UCa = 24-h urine for calcium US = ultrasound.