Risk factors for kidney stones in older women in the southern United States.
BACKGROUND
The occurrence of kidney stones is disproportionate in the southern region of the United States. Risk factors for the occurrence of kidney stones in this geographic area have not been reported previously.


METHODS
The Women's Health Initiative (WHI) is an ongoing multicenter clinical investigation of strategies for the prevention of common causes of morbidity and mortality among postmenopausal women. A case-control ancillary study was conducted on 27,410 (white or black) women enrolled in the 9 southern WHI clinical centers. There were 1,179 cases (4.3%) of kidney stones at the baseline evaluation. Risk factors for stone formation were assessed in cases versus age- and race-matched control subjects.


RESULTS
Risk factors (univariate) included low dietary potassium (2,404 versus 2,500 mg/day, P = 0.006), magnesium (243 versus 253 mg/day, P = 0.003) and oxalate (330 versus 345 mg/day, P = 0.02) intake, as well as increased body mass index (28.5 versus 27.7 kg/m2, P = 0.001) and a history of hypertension (42% versus 34%, P = 0.001). A slightly lower dietary calcium intake (683 versus 711 mg/day, P = 0.04) was noted in case subjects versus control subjects, but interpretation was confounded by the study of prevalent rather than incident cases. Supplemental calcium intake >500 mg/day was inversely associated with stone occurrence.


CONCLUSIONS
Multivariate risk factors for the occurrence of kidney stones in postmenopausal women include a history of hypertension, a low dietary intake of magnesium, and low use of calcium supplements.
Hall
W D
WD
Emory University School of Medicine, Atlanta, Georgia, USA. whall@emory.edu
Pettinger
M
M
Oberman
A
A
Watts
N B
NB
Johnson
K C
KC
Paskett
E D
ED
Limacher
M C
MC
Hays
J
J
D000367:Age Factors; D000368:Aged; D000428:Alcohol Drinking / Q000009:adverse effects; D001581:Benzothiadiazines; D015992:Body Mass Index; D002136:Calcium, Dietary / Q000008:administration & dosage; D004032:Diet; D004232:Diuretics; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000188:drug therapy; D007669:Kidney Calculi / Q000453:epidemiology* / Q000209:etiology*; D016015:Logistic Models; D008274:Magnesium / Q000008:administration & dosage; D008875:Middle Aged; D017419:Potassium, Dietary / Q000008:administration & dosage; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D049993:Sodium Chloride Symporter Inhibitors / Q000009:adverse effects; D012982:Sodium, Dietary / Q000008:administration & dosage; D015144:Southeastern United States / Q000453:epidemiology; D013696:Temperature
D001581:Benzothiadiazines; D002136:Calcium, Dietary; D004232:Diuretics; D017419:Potassium, Dietary; D049993:Sodium Chloride Symporter Inhibitors; D012982:Sodium, Dietary; D008274:Magnesium