Ambulatory blood pressure in relation to interaction between dietary sodium intake and serum uric acid in the young

Figures & data

Table 1. Characteristics of the patients by gender.

Characteristic	Male (n = 488)	Female (n = 128)	p value
Age, years	19.1 ± 3.1	19.3 ± 3.4	0.40
Body mass index, kg/m^2	25.0 ± 4.9	22.5 ± 4.4	<0.0001
Waist circumference, cm	88.1 ± 13.7	77.4 ± 12.8	<0.0001
Current smoking, n (%)	27 (5.5%)	1 (0.8%)	0.02
Alcohol intake, n (%)	15 (3.1%)	1 (0.8%)	0.04
24-h systolic blood pressure, mmHg	133.9 ± 11.9	129.8 ± 14.3	0.001
24-h diastolic blood pressure, mmHg	78.1 ± 9.5	83.9 ± 11.7	<0.0001
Use of antihypertensive drugs, n (%)	347 (71.1%)	104 (81.3%)	0.02
Blood biochemistry
Fasting plasma insulin concentration, µIU/ml	9.8 (6.7–15.0)	9.2 (5.9–13.6)	0.38
Fasting plasma glucose concentration, mmol/L	4.9 (4.6–5.2)	4.8 (4.5–5.1)	0.02
Serum triglycerides concentration, mmol/L	1.3 ± 0.8	1.1 ± 0.6	0.01
High-density lipoprotein cholesterol concentration, mmol/L	1.2 ± 0.3	1.3 ± 0.3	<0.0001
Serum creatinine concentration, µmol/L	80.2 ± 15.3	58.6 ± 9.3	<0.0001
Serum uric acid concentration, µmol/L	394 ± 81	298 ± 76	<0.0001
Hyperuricaemia, n (%)	250 (51.2%)	33 (25.8%)	<0.0001
Urinary measurements
Volume, L	1.4 ± 0.6	1.4 ± 0.5	0.89
Sodium excretion, mmol	151 ± 68	126 ± 63	0.0001
Potassium excretion, mmol	36.9 ± 16.2	31.9 ± 14.3	0.001
Na^+/K^+ ratio	4.6 ± 2.8	4.6 ± 4.0	0.95

Values are arithmetic mean ± standard deviation, median (interquartile range), or number of subjects (%).

Figure 1. Prevalence of hyperuricaemia by age and gender. Symbols represent the prevalence of hyperuricaemia in youths with primary hypertension. p values for trend are given for male and female patients separately.

Table 2. Ambulatory blood pressure and 24-h urinary electrolytes by hyperuricaemia.

Variable	Normal uric acid (n = 333)	Hyperuricaemia (n = 283)	p value
Ambulatory blood pressure, mmHg
24-h systolic	132.6 ± 0.9	131.7 ± 1.1	0.54
24-h diastolic	80.9 ± 0.8	77.5 ± 0.9	0.005
24-h pulse pressure	51.7 ± 0.6	54.2 ± 0.7	0.001
Daytime systolic	137.1 ± 1.0	136.5 ± 1.1	0.71
Daytime diastolic	84.2 ± 0.8	81.8 ± 0.9	0.06
Daytime pulse pressure	52.9 ± 0.7	54.7 ± 0.8	0.09
Night-time systolic	121.9 ± 1.1	121.1 ± 1.3	0.66
Night-time diastolic	72.7 ± 0.9	70.0 ± 1.1	0.07
Night-time pulse pressure	49.2 ± 0.6	51.2 ± 0.7	0.048
24-h urinary measurement
Volume, L	1.4 ± 0.6	1.5 ± 0.6	0.78
Sodium excretion, mmol	139.0 ± 3.9	153.3 ± 4.1	0.01
Potassium excretion, mmol	34.0 ± 0.9	38.3 ± 1.0	0.001
Na^+/K^+ ratio	4.6 ± 0.2	4.4 ± 0.2	0.46

Values per group are least square mean ± standard error, adjusted for sex, age, body mass index, current smoking and alcohol intake, serum creatinine and use of antihypertensive drug.

Table 3. Ambulatory blood pressure according to the quartile distributions of 24-h urinary sodium excretion.

Ambulatory blood pressure, mmHg	24-h urinary sodium excretion
	Quartile 1	Quartile 2	Quartile 3	Quartile 4	p value (for trend)
	(<99.3 mmol/d)	(99.3–139.6 mmol/d)	(139.6–174.5 mmol/d)	(≥174.5 mmol/d)
24-h systolic	132.6 ± 1.0	132.4 ± 1.0	132.4 ± 1.0	134.9 ± 1.0	0.14
24-h diastolic	80.7 ± 0.8	78.4 ± 0.8	79.4 ± 0.8	78.4 ± 0.8	0.12
24-h pulse pressure	51.9 ± 0.7	54.0 ± 0.7	53.0 ± 0.7	56.3 ± 0.7	0.002
Daytime systolic	137.4 ± 1.1	137.0 ± 1.1	137.5 ± 1.1	137.9 ± 1.1	0.68
Daytime diastolic	85.0 ± 0.9	83.2 ± 0.9	83.0 ± 0.9	82.5 ± 0.9	0.04
Daytime pulse pressure	52.4 ± 0.8	53.8 ± 0.9	54.5 ± 0.9	55.4 ± 0.9	0.01
Night-time systolic	121.7 ± 1.2	121.5 ± 1.2	122.2 ± 1.2	123.0 ± 1.2	0.41
Night-time diastolic	72.5 ± 1.0	71.0 ± 1.0	70.9 ± 1.0	71.6 ± 1.0	0.51
Night-time pulse pressure	49.2 ± 0.8	50.4 ± 0.8	51.3 ± 0.8	51.4 ± 0.8	0.04

Values per group are least square mean ± standard error, adjusted for sex, age, body mass index, current smoking and alcohol intake, serum creatinine and use of antihypertensive drug.

p Values for trend are given.

Figure 2. 24-h, daytime and night-time systolic blood pressure according to the quartile distributions of 24-h urinary sodium excretion in patients with hyperuricaemia. Symbols represent mean value adjusted for age, sex, body mass index, current smoking and alcohol intake and use of antihypertensive drugs. The vertical lines denote standard error. p values for trend are given.