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Table 1 Baseline characteristics based on urine osmolality quartiles in 2009–2012 NHANES participants

From: The association of urine osmolality with decreased kidney function and/or albuminuria in the United States

Characteristic

 

Urine Osmolality (mOsm/kg)

Total Sample

(N = 7373)

Quartile 1

(N = 1706)

Quartile 2

(N = 1811)

Quartile 3

(N = 1879)

Quartile 4

(N = 1977)

Urine osmolality (mOsm/kg)

627.4 (5.9)

250.0 (2.2)

540.5 (2.5)

756.9 (1.4)

963.0 (2.6)

Serum glucose (mg/dL)

96.4 (0.4)

92.2 (0.5)

97.3 (0.7)

99.4 (1.0)

96.7 (0.7)

Age (years)

42.9 (0.4)

43.6 (0.6)

46.2 (0.6)

43.9 (0.4)

38.1 (0.5)

Male (%)

51.4

40.4

50.8

53.4

61.1

Race/ethnicity (%)

 Non-Hispanic white

67.3

73.8

70.9

66.0

58.6

 Non-Hispanic black

10.5

6.3

10.2

11.1

14.6

 Mexican American

9.0

6.7

6.8

9.7

12.7

 Hispanic

6.0

5.0

5.0

5.7

8.0

 Other races

7.2

8.2

7.2

7.5

6.1

Education (%)

  < High school diploma

15.6

14.3

15.3

16.9

16.1

 High school diploma

20.9

18.4

20.8

20.4

24.0

  ≥ Some college

63.5

67.3

64.0

62.8

59.9

Income-to-poverty (%)a

  < 1

15.2

14.4

12.6

15.8

18.0

Smoking (%)b

 Never

56.2

55.5

54.6

54.2

60.3

 Former

21.9

20.2

23.6

25.4

18.5

 Current

21.9

24.3

21.8

20.4

21.2

Sodium intake (mg/d)

3677.9 (25.7)

3475.6 (53.4)

3631.3 (60.1)

3752.6 (38.5)

3852.4 (45.0)

BMI (kg/m2) (%)c

  < 25

32.0

44.9

32.0

26.2

24.6

 25–30

33.7

32.8

34.6

34.5

32.7

  ≥ 30

34.4

22.3

33.3

39.3

42.7

Diabetes (%)d

9.6

6.8

11.6

12.4

7.7

Hypertension (%)e

35.5

33.3

39.7

39.9

29.1

Coronary artery disease (%)

1.6

1.6

2.1

1.3

1.4

Decreased eGFR ± albuminuria (%)f

6.7

6.2

8.6

7.5

4.3

Decreased eGFR (%)

2.2

1.9

3.8

2.0

0.8

eGFR (mL/min/1.73m2)

98.8 (0.5)

99.0 (0.6)

95. 0 (0.7)

98.2 (0.7)

102.8 (0.7)

Albuminuria ≥ 30 mg/gm (%)g

5.0

4.7

5.7

6.0

3.5

Log-transformed ACR

1.9 (0.0)

1.9 (0.0)

1.9 (0.0)

1.9 (0.0)

1.8 (0.0)

  1. Abbreviations: NHANES National Health and Nutrition Examination Survey, SE Standard Error, BMI Body Mass Index, eGFR estimated Glomerular Filtration Rate, ACR urine Albumin-to-Creatinine Ratio
  2. Weighted data are expressed as the mean (SE) or percentage of participants. No random urine electrolytes in this publicly available dataset. No differences in serum sodium, potassium, and calcium in each osmolality quartile.
  3. a Income-to-poverty ratio < 1 if family income below the federal poverty threshold
  4. bFor self-reported smoking status, current smokers if currently smoking, former smokers if smoke > 100 in lifetime, but not current, and never smokers if not current and less than 100 in lifetime
  5. cObese if BMI ≥ 30 kg/m2, overweight if BMI ≥ 25 to < 30 kg/m2, and underweight to normal if < 25 kg/m2
  6. dDiabetes was defined as 1) self-report including borderline diabetes by using the question “Have you ever been told by a doctor or health professional that you have diabetes?” 2) use of diabetes medications, or 3) HbA1C ≥ 6.5%
  7. eHypertension was defined as self-report, use of antihypertensive agents, mean systolic BP ≥ 130 mmHg, or mean diastolic BP ≥ 80 mmHg
  8. fDecreased eGFR was defined by eGFR < 60 mL/min/1.73m2. Albuminuria was defined by ACR ≥ 30 mg/gm. The total unweighted number of cases was 610. The prevalence from the lowest to highest quartiles of osmolality was 116 (6.2%), 213 (8.6%), 179 (7.5%), and 102 (4.3%), respectively (p-value for trend = 0.02)
  9. gAlbuminuria was based on spot urine albumin-to-creatinine ratio
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BMC Nephrology

ISSN: 1471-2369

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