Urinary stone risk factors in the siblings of patients with calcium renal stones.
OBJECTIVE
We determined which, if any, urinary stone risk factors accurately discriminate stone forming and nonstone forming siblings of patients with calcium renal stones.


METHODS
A total of 252 siblings of stone formers provided 2, 24-hour urine samples, which were sent overnight and analyzed at a central laboratory. Standard stone risk factors were measured and the supersaturation of calcium oxalate, calcium phosphate and uric acid was calculated.


RESULTS
Discriminant functions were derived for each gender by multivariate analysis. In stone forming sisters higher urinary calcium and pH discriminated with a success rate of 70%. In stone forming brothers higher urinary calcium, lower urinary potassium and older age discriminated with a success rate of 79%.


CONCLUSIONS
Select urinary measurements as well as age classify siblings into those with and without stones with fair accuracy. Calcium excretion and urinary pH in females, and calcium excretion, urinary potassium and age in males are feasible identifiers of stone forming siblings. To determine whether these measurements can be used to predict new stone onset may require years of observation of our current cohort.
Kinder
Jennifer M
JM
Litholink Corp. and Nephrology Section, University of Chicago Pritzker School of Medicine, Chicago, Illinois, USA.
Clark
Cyndi D
CD
Coe
Brian J
BJ
Asplin
John R
JR
Parks
Joan H
JH
Coe
Fredric L
FL
D000328:Adult; D000367:Age Factors; D000368:Aged; D002118:Calcium / Q000652:urine*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007669:Kidney Calculi / Q000235:genetics* / Q000652:urine; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000652:urine; D012307:Risk Factors; D012737:Sex Factors
D011188:Potassium; D002118:Calcium