Table 1 Baseline characteristics of patients by serum Sodium concentration (mmol/L) in the Irish Health System

Observations n (%)

32,666

2503 (7.7)

29,908 (91.6)

255 (0.8)

Mean Age at baseline (SD)

32,666

65.9 (16.8)

56.1 (17.9)

63.3 (18.3)

Sex

 Women

17,367

48.8

53.6

44.7

 Men

15,299

51.2

46.4

55.3

Clinical setting at baseline ^a

 Emergency Department

4,835

30.1

13.5

16.9

 General Practice

15,293

19.7

49.4

21.2

 Inpatient

7,543

37.7

21.6

56.1

 Outpatient

4,965

12.5

15.5

5.9

Markers of renal function

 Urea (mmol/L) (Median IQR)

32,666

5.3 (3.8–8.2)

4.9 (3.8–6.2)

7.9 (5.2–14.1)

 Serum creatinine (µmol/L) (Median IQR)

32,666

81.0 (64.0–108.0)

77.0 (65.0–91.0)

97.0 (78.0–140.0)

 Baseline eGFR ^b (ml/min/1.73m²) (Median IQR)

32,666

76.5 (50.9–93.6)

86.4 (68.5–101.2)

63.1 (36.3–86.7)

eGFR Category (ml/min/1.73m²) ^b

 eGFR >  = 90

13,882

30.1

43.7

20.8

 eGFR 60–89

12,867

36.8

39.7

33.7

 eGFR 30–59

4,755

21.9

13.8

29.8

 eGFR 15–29

814

7

2

11.8

 eGFR < 15

348

4.4

0.8

3.9

Inflammatory Markers

 Haemoglobin (g/dl) (Mean SD)

26,561

12.4 (2.1)

13.5 (1.8)

12.4 (2.5)

 White blood count (× 10⁹/L) (Median IQR)

26,561

9.2 (6.7–12.7)

7.2 (5.8–9.4)

10.5 (7.2–15.0)

 Lymphocyte count (× 10⁹/L) (Median IQR)

26,561

1.2 (0.8–1.7)

1.7 (1.3–2.2)

1.3 (0.8–1.9)

 Neutrophil count (× 10⁹/L) (Median IQR)

26,561

6.8 (4.4–10.4)

4.4 (3.3–6.3)

8.4 (4.7–12.3)

Nutritional and Metabolic Markers

 Serum Albumin (g/L) (Mean SD)

32,666

32.6 (7.3)

37.7 (5.5)

29.7 (9.5)

 Serum Calcium (mmol/L) (Mean SD)

32,666

2.2(0.2)

2.3 (0.1)

2.2 (0.3)

 Serum Phosphorus (mmol/L) (Mean SD)

32,666

1.2(0.4)

1.2 (0.3)

1.2 (0.5)

 Serum Potassium (mmol/L) (Mean SD)

32,666

4.3(0.8)

4.4 (0.5)

4.1 (0.8)

Lipid related Markers

 Total Cholesterol (mmol/L) (Mean SD)

17,188

4.7 (1.3)

5.1 (1.1)

4.9 (1.2)

 Triglycerides (mmol/L) (Mean SD)

14,302

1.3 (1.1)

1.4 (0.9)

1.6 (1.2)

Glycaemic markers

 Glucose (mmol/L) (Median IQR)

32,666

6.6 (5.4–10.1)

5.2 (4.8–6.1)

6.2 (5.2–8.0)

Markers of Liver function

 Alanine Alkaline phosphatase (IU/L) (Median IQR)

31,599

79.0 (61.0–105.0)

68.0 (55.0–84.0)

75.0 (57.2–97.0)

 Alanine transaminase (IU/L) (Median IQR)

31,131

23.0 (17.0–35.0)

23.0 (17.0–32.0)

24.0 (18.0–42.0)

 Gamma-glutamyltransferase (IU/L) (Median IQR)

31,196

34.0 (21.0–67.0)

24.0 (17.0–39.0)

31.0 (21.0–70.0)

 Total bilirubin (µmol/L) (Median IQR)

30,867

13.0 (10.0–19.0)

12.0 (9.0–16.0)

14.0 (10.0–21.0)