Risk factors for nephrolithiasis in patients with familial idiopathic hypercalciuria.
OBJECTIVE
About 40% of patients with nephrolithiasis have idiopathic hypercalciuria, sometimes associated with a family history of kidney stones. In these families, little is known about the frequency of, and risk factors for, stone formation among hypercalciuric patients. We therefore conducted a prospective study of 216 subjects from 33 families with idiopathic hypercalciuria.


METHODS
We recorded the age, weight, and history of calcium stones in all subjects, and measured 24-hour urine volume and excretion of calcium, uric acid, sodium, magnesium, urea, citrate, phosphate, and sulfate on a nonrestricted diet. We performed a more complete metabolic evaluation in many of the hypercalciuric subjects (calciuria/weight >0.1 mmol/kg/d). Multivariate logistic regression analysis was performed to identify independent risk factors for stone formation.


RESULTS
The prevalence of self-reported nephrolithiasis was 46% (61/132) in hypercalciuric subjects and 11% (7/63) in normocalciuric subjects (P <0.0001). In multivariate analysis, age (odds ratio [OR] per 10 years of age = 1.3; 95% confidence interval [CI]: 1.1 to 1.6), urine calcium excretion (OR = 1.3 per mmol/d increase; 95% CI: 1.2 to 1.5), and uric acid excretion (OR = 3.3 per mmol/d increase; 95% CI: 1.4 to 7.5) were independent risk factors for nephrolithiasis. The risk of nephrolithiasis increased progressively with greater levels of hypercalciuria.


CONCLUSIONS
We found a significant dose-effect association between calciuria and stone disease in patients with familial hypercalciuria. Other factors associated with stone formation included higher uric acid excretion, probably reflecting higher food intake, and age, probably reflecting the length of exposure to hypercalciuria and hyperuricosuria.
Service de Néphrologie A, Hôpital Tenon, Paris, France.
Nicolas
N
Lerolle
Brigitte
B
Lantz
Françoise
F
Paillard
Bernard
B
Gattegno
Antoine
A
Flahault
Pierre
P
Ronco
Pascal
P
Houillier
Eric
E
Rondeau
D000328:Adult; D017677:Age Distribution; D000368:Aged; D002118:Calcium / Q000652:urine*; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000453:epidemiology* / Q000235:genetics; D007669:Kidney Calculi / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D015995:Prevalence; D011336:Probability; D011446:Prospective Studies; D012307:Risk Factors; D017678:Sex Distribution; D018709:Statistics, Nonparametric
D002118:Calcium