Vitamin D deficiency is often detected during metabolic evaluation in the nephrolithiasis population. Multiple vitamin D repletion protocols exist, however their differing impact on urinary stone formation risk factors is unclear.
Patients with a history of calcium stones and vitamin D deficiency (<30ng/ml) were randomized to receive either 1,000 International Units (IU) daily or 50,000 IU weekly of vitamin D supplementation for 6 weeks. Patients completed a pre- and post-treatment serum vitamin D level and 24-hour urine collections to assess response and any changes in urine stone formation risk parameters.
Twenty one patients completed the study; 8 receiving 1,000 IU daily and 13 receiving 50,000 IU weekly. The 50,000 IU weekly group showed significant increase in median serum vitamin D levels of 23 ng/ml (135%% increase, p<0.01), while the 1,000 IU daily group showed a non-significant median increase of 9 ng/ml (49% increase, p=0.12). Post-repletion 24-hour urine analysis showed no significant change in urine calcium among groups; median change of -11 mg in patients receiving 1,000 IU [IQR -143, 29] and -16 mg in those receiving 50,000 IU [IQR -42, 66]. Between the groups there was no significant difference in the super-saturation of calcium oxalate or calcium phosphate.
High dose and low dose vitamin D repletion had no effect on urinary calcium excretion or the super-saturation of calcium salts in known stone formers. The higher dosing regimen had superior repletion and may be the optimal protocol in patients with vitamin D deficiency.
The Journal of urology. 2016 Oct 17 [Epub ahead of print]
Matthew C Ferroni, Kevin J Rycyna, Timothy D Averch, Michelle J Semins
Department of Urology, University of Pittsburgh Medical Center, Pittsburgh, PA; National Institutes of Health., Department of Urology, University of Pittsburgh Medical Center, Pittsburgh, PA; National Institutes of Health. Electronic address: .
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