Dietary and lifestyle factors and medical conditions associated with urinary citrate excretion.

BACKGROUND AND OBJECTIVES Lower urinary citrate excretion is a risk factor for nephrolithiasis and associated with metabolic acidosis and higher prevalence of hypertension and insulin resistance. This study sought to quantify the independent predictors of urinary citrate excretion in population-based cohorts. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS A cross-sectional study of 2561 individuals from the Health Professionals Follow-Up Study and Nurses' Health Studies I and II who provided two 24-hour urine collections was conducted. Dietary data were ascertained from the semiquantitative food frequency questionnaire. Lifestyle and disease data were derived from responses to biennial questionnaires. Multivariable linear regression was used to quantify the predictors of urinary citrate excretion. RESULTS After adjusting for age, urinary creatinine, dietary, and other factors, higher intake of nondairy animal protein (per 10 g/d; -20 mg/d; 95% confidence interval [-29 to -11]), higher body mass index (per 1 kg/m(2); -4 mg/d; [-6 to -2]), and history of nephrolithiasis (-57 mg/d; [-79 to -36]), hypertension (-95 mg/d; [-119 to -71]), gout (-104 mg/d; [-155 to -54]), and thiazide use (-34 mg/d; [-68 to -1]) were independently associated with lower 24-hour urinary citrate excretion. Higher intake of potassium (per 1000 mg/d; 53 mg/d; [33 to 74]), higher urinary sodium (per 100 mEq/d; 56 mg/d; [31 to 80]), and history of diabetes (61 mg/d; [21 to 100]) were independently associated with higher citrate excretion. CONCLUSIONS Several dietary and lifestyle factors and medical conditions are independently associated with urinary citrate excretion.