Table 1.

Characteristics of 3757 patients with CKD according to quartile of 24-hour urinary excretion of sodium and potassium (the CRIC Study)

VariableUrinary Sodium Excretion, mmol/24 hUrinary Potassium Excretion, mmol/24 h
<116.8 (n=940)116.8–153.6 (n=939)153.7–194.5 (n=938)≥194.6 (n=940)P Value for Group Difference<39.4 (n=939)39.4–52.1 (n=940)52.2–67.0 (n=938)≥67.1 (n=940)P Value for Group Difference
Age, yr59.7±10.658.4±10.957.6±10.955.2±10.8<0.00157.5±11.357.6±11.257.6±10.958.2±10.30.60
Men, %37.848.164.072.4<0.00140.447.759.474.9<0.001
Race/ethnicity, %
 White44.946.948.548.80.0428.040.054.266.9<0.001
 Black41.840.341.941.861.848.434.421.2
 Other13.312.99.69.410.211.611.411.9
High school graduate, %76.778.381.683.9<0.00170.978.883.087.8<0.001
Current smoking %15.011.811.512.80.1020.613.211.26.2<0.001
Weekly alcohol drinking, %17.919.524.620.50.00314.817.223.227.2<0.001
Physical activity, METs/wk174.4±121.2193.8±131.1208.3±152.7220.2±165.2<0.001194.5±160.3194.4±133.2200.3±143.2207.4±140.00.20
Total calorie intake, kcal/24 h1675±7191808±7961846±8321996±884<0.0011759±8471795±8601824±7511939±806<0.001
Hypertension, %83.484.588.587.90.00289.287.784.582.8<0.001
Diabetes, %40.248.047.755.2<0.00143.051.748.547.90.002
History of CVD, %31.335.432.333.00.3034.933.331.831.90.40
Antihypertensive medication, %87.692.293.694.1<0.00193.492.791.090.50.07
 Diuretics56.859.358.262.10.1062.160.156.757.50.07
 RAS blocking agents58.669.072.375.3<0.00164.371.571.268.30.002
 Other antihypertensive medicationsa67.573.470.070.90.0472.672.368.568.30.06
Systolic BP, mmHg128.4±23.2127.8±22.8128.4±21.1127.8±20.10.90129.9±23.2129.7±22.9126.7±20.9126.1±20.1<0.001
Diastolic BP, mmHg70.2±12.870.5±12.471.9±12.773.3±12.8<0.00172.0±13.471.6±12.670.9±12.671.4±12.20.30
Waist circumference, cm98.9±16.5103.8±17.0107.2±15.5112.7±17.6<0.001101.1±17.1106.0±17.5106.7±17.1108.8±17.0<0.001
Body mass index, kg/m229.1±6.931.2±7.232.4±6.834.9±8.1<0.00130.4±7.532.4±7.832.2±7.332.7±7.5<0.001
Lean body mass index, kg/m219.0±3.820.2±3.821.5±3.723.2±4.2<0.00119.5±3.720.8±4.121.3±4.122.3±4.2<0.001
LDL-cholesterol, mg/dl102.3±36.5104.2±35.6103.0±35.4100.0±34.30.07103.4±37.2103.4±37.3103.1±35.299.6±31.90.05
HDL-cholesterol, mg/dl51.6±18.148.1±15.146.0±13.544.4±13.9<0.00149.0±16.648.5±16.046.9±14.645.6±14.5<0.001
Triglycerides, mg/dl149.1±108.5150.4±97.0164.3±144.3162.0±109.4<0.01155.0±108.4150.2±117.1160.0±130.3160.7±107.80.20
Glucose, mg/dl109.4±49.1113.2±48.4116.1±53.2119.5±49.2<0.001110.6±46.1116.8±55.5116.6±51.2114.3±47.00.02
HbA1c, %6.4±1.56.6±1.56.7±1.66.8±1.6<0.0016.5±1.66.7±1.66.7±1.56.6±1.50.03
Urinary sodium, mmol/24 h90.2±20.1135.8±10.4173.6±11.8244.0±48.8<0.001123.1±44.4154.1±51.0169.2±54.2197.2±73.4<0.001
Urinary potassium, mmol/24 h44.0±19.451.0±21.057.5±19.369.1±28.3<0.00130.5±6.645.9±3.759.0±4.386.1±24.4<0.001
Urinary creatinine, mg/24 h1046±3211255±3581487±4041707±480<0.0011085±3371294±3941449±4221667±492<0.001
Urinary protein, g/24 h0.12 (0.06–0.59)0.16 (0.07–0.70)0.22 (0.07–1.00)0.31 (0.09–1.49)<0.0010.20 (0.07–0.88)0.19 (0.07–0.97)0.19 (0.07–1.00)0.16 (0.08–0.82)0.40
eGFR, ml/min per 1.73 m242.5±15.243.9±14.744.3±14.347.3±15.1<0.00141.5±15.243.4±14.444.5±14.648.5±14.6<0.001
  • Values are percentage of participants, mean±SD, or median (interquartile range). METs, metabolic equivalents; RAS, renin-angiotensin; HbA1c, glycated hemoglobin.

  • a Other hypertension medications include α-blockers, β-blockers, calcium channel blockers, and vasodilators.