Bone mineral density and urine calcium excretion among subjects with and without nephrolithiasis.
BACKGROUND
Bone mineral density (BMD) is reduced among patients with idiopathic hypercalciuria (IH) and nephrolithiasis. To disentangle effects of diet, stone formation, and physiology upon BMD, we studied vertebral and femoral neck BMD among relatives of hypercalciuric stone formers, and contrasted those with to those without stones.


METHODS
Among 59 subjects from 11 families, vertebral and femoral neck BMD, diet calcium intake, urine excretions of calcium, sodium, ammonium, titratable acid, sulfate, urea nitrogen, and serum levels of calcitriol and markers of bone turnover were studied.


RESULTS
Stone formers (SF) consumed less calcium than non-stone formers (NSF). Spine and femoral neck BMD z-scores varied inversely with urine calcium loss and urine ammonium excretion among SF but not NSF. No correlations of BMD z-score were found for bone markers, calcitriol, or any of the other measurements.


CONCLUSIONS
SF consumed less calcium, presumably to prevent more stones, and displayed a bone mineral responsiveness to calcium loss and ammonium excretion not present among NSF, who ate more calcium. Lowered calcium consumption in IH, perhaps in response to stone formation, alters bone responses in a direction that can predispose to mineral loss and eventual fracture.
Asplin
John R
JR
Litholink Corporation, and Renal Section, University of Chicago, Chicago, Illinois 60612, USA.
Bauer
Kimberly A
KA
Kinder
Jennifer
J
Müller
Georg
G
Coe
Brian J
BJ
Parks
Joan H
JH
Coe
Fredric L
FL
D000328:Adult; D000368:Aged; D015519:Bone Density; D002118:Calcium / Q000652:urine*; D002136:Calcium, Dietary / Q000008:administration & dosage; D016022:Case-Control Studies; D005272:Femur Neck / Q000378:metabolism; D006801:Humans; D007669:Kidney Calculi / Q000378:metabolism* / Q000652:urine; D008875:Middle Aged; D000644:Quaternary Ammonium Compounds / Q000652:urine; D013131:Spine / Q000378:metabolism
D002136:Calcium, Dietary; D000644:Quaternary Ammonium Compounds; D002118:Calcium