The association of serum gamma-glutamyl transpeptidase level and other laboratory parameters with blood pressure in hypertensive patients under ambulatory blood pressure monitoring

Figures & data

Table 1 Demographic and epidemiologic characteristics of the patients

Variable	Dipper group (n=99)	Non-dipper group (n=72)	P-value
Sex (female/male), n (%)	65 (66)/34 (34)	48 (67)/24 (33)	0.890
Age (years), mean ± SD	43.8±13.7	52.3±14.4	0.0002
BMI (kg/m^2), mean ± SD	28.5±5.1	28.3±4.1	0.780
Smoking, n (%)	32 (32)	22 (31)	0.800
Diabetes mellitus, n (%)	13 (13)	7 (10)	0.490
Coronary artery disease, n (%)	9 (9)	8 (11)	0.660
Chronic kidney failure, n (%)	4 (4)	2 (2)	0.800
Antihypertensive drug usage, n (%)
One drug only	16 (16)	6 (8)	0.130
Two drugs	64 (65)	48 (67)	0.780
Three or more drugs	19 (19)	18 (25)	0.360

Abbreviations: BMI, body mass index; SD, standard deviation.

Table 2 Comparison of the biochemical parameters of the patients

Blood biochemistry	Dipper group (n=99)	Non-dipper group (n=72)	P-value
	Mean ± SD	Mean ± SD
GGT, U/L	20.5±8.8	36.2±13.8	0.030
Creatinine, mg/dL	0.74±0.22	0.8±0.3	0.220
ALT, U/L	24.7±18.9	22.4±12.8	0.370
Total cholesterol, mg/dL	196.1±50.7	197.1±53.4	0.900
LDL-cholesterol, mg/dL	112.6±36.4	116.6±36.4	0.540
HDL-cholesterol, mg/dL	51.9±13.1	50.6±15.3	0.610
Triglyceride, mg/dL	157.8±38.1	153.9±40.2	0.730
Albumin, g/dL	4.37±0.99	4.36±0.3	0.530
CRP, mg/L	3.78±4.6	7.2±7.1	0.020
Uric acid, mg/dL	5.14±2.1	6.3±1.6	0.010

Abbreviations: ALT, alanine aminotransferase; CRP, C-reactive protein; GGT, gamma-glutamyl transpeptidase; HDL, high-density lipoprotein; LDL, low-density lipoprotein; SD, standard deviation.

Table 3 Comparison of the laboratory parameters according to mean blood pressure level

Blood biochemistry	Lower blood pressure group (n=104)	Higher blood pressure group (n=67)	P-value
	Median (range)	Median (range)
GGT, U/L	67.5 (24–306)	65 (44–384)	0.429
Creatinine, mg/dL	0.7 (0.5–2)	0.8 (0.5–3)	0.015
ALT, U/L	18.5 (5–174)	22.5 (10–74)	0.270
Total cholesterol, mg/dL	195.5 (90–319)	196.5 (113–290)	0.562
LDL-cholesterol, mg/dL	115 (35–211)	120 (39–190)	0.430
HDL-cholesterol, mg/dL	47.5 (31–94)	46 (53–101)	0.269
Triglyceride, mg/dL	147 (80–436)	161 (42–526)	0.351
Albumin, g/dL	4.6 (1.1–5.2)	4.4 (0.5–4.9)	0.178
CRP, mg/L	3 (2–14)	3 (2–147)	0.086
Uric acid, mg/dL	5 (3–11)	6 (1–12)	0.140

Abbreviations: ALT, alanine aminotransferase; CRP, C-reactive protein; GGT, gamma-glutamyl transpeptidase; HDL, high-density lipoprotein; LDL, low-density lipoprotein.

Table 4 Comparison of ambulatory blood pressure monitoring results of the groups

Ambulatory blood pressure (mmHg)	Dipper group	Non-dipper group	P-value
	Mean ± SD	Mean ± SD
SBP, daytime	131.3±18.8	128.8±17.4	0.370
SBP, nighttime	116.1±15.3	125±19.5	0.001
SBP, mean	127.1±17.0	127.5±17.0	0.880
DBP, daytime	82.9±12.6	80.2±11.1	0.140
DBP, nighttime	70.8±10.7	76.9±13.3	0.001
DBP, mean	79.4±11.6	79.3±11.2	0.950
SBP, decrease	12.6±4.3	4.3±4.5	0.0001
DBP, decrease	15.1±4.2	5±4.8	0.0001

Abbreviations: DBP, diastolic blood pressure; SBP, systolic blood pressure; SD, standard deviation.

Table 5 The correlation analysis between the laboratory and ambulatory blood pressure monitoring findings

Variable	SBP, nighttime		DBP, nighttime		SBP, diurnal decrease		DBP, diurnal decrease
	r	P-value	r	P-value	r	P-value	r	P-value
GGT, U/L	0.09	0.200	0.08	0.230	−0.153	0.040	−0.16	0.030
CRP, mg/L	0.125	0.040	0.15	0.040	−0.18	0.020	−0.17	0.010
Uric acid, mg/dL	0.15	0.100	0.09	0.200	−0.23	0.001	−0.21	0.001

Abbreviations: CRP, C-reactive protein; DBP, diastolic blood pressure; GGT, gamma-glutamyl transpeptidase; r, correlation coefficient; SBP, systolic blood pressure.

Table 6 Results of multiple logistic regression analysis for risk factors for non-dipper hypertension

Risk factors	OR	95% CI	P-value
Age	1.02	0.989–1.047	0.222
CRP	1.09	0.953–1.248	0.210
Uric acid	0.97	0.791–1.193	0.782
GGT	1.01	0.996–1.017	0.240

Abbreviations: CI, confidence interval; CRP, C-reactive protein; GGT, gamma-glutamyl transpeptidase; OR, odds ratio.