Prevalence and metabolic abnormalities of vitamin D-inadequate patients presenting with urolithiasis to a tertiary stone clinic.
[cystinuria]
To assess the prevalence and metabolic abnormalities of patients with inadequate vitamin D (VD) presenting with urolithiasis to a tertiary stone clinic in North America.A retrospective review of consecutive patients presenting from August 2009 to January 2010 was performed. Demographic and clinical data were collected together with metabolic stone workup, including 2 24-hour urine collections and serum 25-hydroxy VD [25(OH)D]. VD inadequacy (VDI) included VD deficiency and VD insufficiency defined as 25-(OH) VD levels <20 ng/mL and 21-29 ng/mL, respectively.Of 101 patients, 81 (80.2%) were found to have VDI: 34 (33.7%) were deficient and 47 (46.5%) had insufficient VD. Mean age was 50.4 ± 15.8 years and the mean body mass index was 28.7 ± 5.8 kg/m(2). Forty-two percent were smokers, 51% were recurrent stone formers, and 54% had positive family history of urolithiasis. Hyperparathyroidism was detected in 25.9% of patients, of which 91% of them were secondary to VDI. Hypocalcemia and hyperuricemia were found in 36% and 11% of patients, respectively. Of 81 VDI patients, 69 (85.2%) had complete 24-hour urine collections, of which 92.7% had at least one abnormality. However, only 40% of patients with normal VD had metabolic abnormalities (P <.0001). The most prevalent pattern of urinary abnormalities in VDI patients were suboptimal volume (45%), hypocitaturia (24%), hypocalciuria (33%), hypercalciuria (20%), hyperuricosuria (16%), cystinuria (5%), and hyperoxaluria (7.2%).In this preliminary study, patients presenting with urolithiasis were found to have a high prevalence of inadequate VD associated with abnormalities on metabolic stone work-up.
