Objective: To characterize the effect of vitamin D(3) intake on urinary calcium:creatinine ratios across predefined ranges of serum 25(OH)D.
Design: Patients with multiple sclerosis (n=25) received escalating doses of vitamin D(3) (4000-40,000IU/d) with calcium (1200mg/d).
Results: Urinary calcium:creatinine was driven by increased 25(OH)D when concentrations were <75nmol/L (r=0.424, p=0.009) and >200nmol/L (r=0.281, p=0.01), but no relationship existed when 25(OH)D concentrations were 76-200nmol/L.
Conclusions: A "safe", physiological range of 25(OH)D concentrations is 75-200nmol/L.
Trial registration: ClinicalTrials.gov NCT00644904.
Copyright © 2011 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.