title: Vitamin D deficiency is prevalent among idiopathic stone formers, but does correction pose any risk?
abstract: While vitamin D (vitD) deficiency is thought to contribute to poor health in a variety of ways and should be corrected, there is still concern about giving vitD supplements to patients with a history of nephrolithiasis. The aim is to study the prevalence of vitD deficiency and the effect on stone risk of cholecalciferol (vitD3) supplementation in a cohort of idiopathic stone formers (ISF). We screened for vitD deficiency and urinary measures of stone risk, comparing vitD deficient (serum 25-OH vitD ≤30 nmol/L; ≤12 ng/mL) with vitD insufficient (31-75 nmol/L; 13-30 ng/mL) or vitD replete (>75 nmol/L; >30 ng/mL); we investigated the effect of giving vitD3 (20,000 IU orally, weekly for 4 months) to 37 of the vitD deficients. Thirty-one percent (142/456) were vitD deficient, 57% (259/456) vitD insufficient, and the rest (12%) vitD replete (55/456). Comparison among the groups showed that baseline 24-h urinary measures related to stone risk expressed as concentration ratios over urine creatinine (Cr), such as U. Calcium/Cr, U. Oxalate/Cr, U. Citrate/Cr, and U. Uric acid/Cr were not significantly different. VitD3 supplementation did significantly increase serum 25-OH vitD levels and U. Phosphate/Cr ratios, as well as reduce serum parathyroid hormone (PTH) concentrations. Following vitD3 supplementation, there was an overall rise in 24-h urine calcium excretion, but it failed to reach statistical significance (p = 0.06). U. Calcium/Cr increased in 22 out of 37 patients (average increase +0.07 mmol/mmol), decreased in 14 (average decrease -0.13 mmol/mmol), and remained unchanged in 1; 6 out of 26 initially normocalciuric ISF developed hypercalciuria; and 6 out of 9 patients who became vitD replete were hypercalciuric after supplementation. It is appropriate to monitor urinary Ca excretion in vitD-supplemented stone formers, because it may reveal underlying hypercalciuria in some treated patients.
authors.affiliation: UCL Centre for Nephrology, Department of Clinical Biochemistry, Royal Free Campus and Hospital, Rowland Hill Street, London, NW3 2PF, UK.
authors.forename: Nikhil
authors.initials: N
authors.lastname: Johri
authors.affiliation: UCL Centre for Nephrology, Department of Clinical Biochemistry, Royal Free Campus and Hospital, Rowland Hill Street, London, NW3 2PF, UK.
authors.forename: Philippe
authors.initials: P
authors.lastname: Jaeger
authors.affiliation: UCL Centre for Nephrology, Department of Clinical Biochemistry, Royal Free Campus and Hospital, Rowland Hill Street, London, NW3 2PF, UK.|Division of Nephrology, Department of Medical Sciences, Gemelli University Hospital, Catholic University of the Sacred Heart, Rome, Italy.
authors.forename: Pietro M
authors.initials: PM
authors.lastname: Ferraro
authors.affiliation: UCL Centre for Nephrology, Department of Clinical Biochemistry, Royal Free Campus and Hospital, Rowland Hill Street, London, NW3 2PF, UK. lshavit@szmc.org.il.|Adult Nephrology Unit, Shaare Zedek Medical Center, Jerusalem, Israel. lshavit@szmc.org.il.
authors.forename: Linda
authors.identifier: http://orcid.org/0000-0002-0294-4916
authors.initials: L
authors.lastname: Shavit
authors.affiliation: UCL Centre for Nephrology, Department of Clinical Biochemistry, Royal Free Campus and Hospital, Rowland Hill Street, London, NW3 2PF, UK.
authors.forename: Devaki
authors.initials: D
authors.lastname: Nair
authors.affiliation: UCL Centre for Nephrology, Department of Clinical Biochemistry, Royal Free Campus and Hospital, Rowland Hill Street, London, NW3 2PF, UK.|Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK.
authors.forename: William G
authors.initials: WG
authors.lastname: Robertson
authors.affiliation: Division of Nephrology, Department of Medical Sciences, Gemelli University Hospital, Catholic University of the Sacred Heart, Rome, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Gambaro
authors.affiliation: UCL Centre for Nephrology, Department of Clinical Biochemistry, Royal Free Campus and Hospital, Rowland Hill Street, London, NW3 2PF, UK.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Unwin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002118:Calcium / Q000378:metabolism* / Q000652:urine; D002762:Cholecalciferol / Q000009:adverse effects*; D015331:Cohort Studies; D003404:Creatinine / Q000652:urine; D019587:Dietary Supplements / Q000009:adverse effects*; D005260:Female; D006801:Humans; D053565:Hypercalciuria / Q000139:chemically induced / Q000652:urine*; D007669:Kidney Calculi / Q000097:blood / Q000453:epidemiology / Q000652:urine*; D008297:Male; D008875:Middle Aged; D010710:Phosphates / Q000652:urine; D015995:Prevalence; D065667:Renal Elimination / Q000187:drug effects; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000188:drug therapy / Q000453:epidemiology* / Q000652:urine; D055815:Young Adult
chemical_list: D010710:Phosphates; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D; D003404:Creatinine; D002118:Calcium
keywords: Calcium; Kidney; Nephrolithiasis; Renal stones; Vitamin D