Study On The Relationship Between 24h Urinary Sodium And Ambulatory Blood Pressure In Patients With Essential Hypertension

Objective:To investigate the relationship between 24-h urinary sodium levels and ambulatory blood pressure monitoring outcomes including blood pressure levels,blood pressure rhythm,blood pressure variability,and early morning blood pressure in patients with essential hypertension.Method:A total of 370 patients with essential hypertension who underwent 24-hour urine sodium testing and 24-hour ambulatory blood pressure monitoring in Fujian Provincial Hospital from January 2016 to September 2020 were selected for the study based on the inclusion and exclusion criteria.Basic data,medication use,laboratory data,cardiotocography,and 24-hour ambulatory blood pressure related data(including All-day average systolic blood pressure(24h SBP),Daytime average systolic blood pressure(d SBP),Nighttime average systolic blood pressure(n SBP),All-day average diastolic blood pressure(24h DBP),Daytime average diastolic blood pressure(d DBP),Nighttime average diastolic blood pressure(n DBP),All-day mean arterial pressure(24h MAP),24-h average heart rate(24h HR),The standard deviation of the 24 h systolic blood pressure fluctuations(24h SBPSD),The standard deviation of the 24 h diastolic blood pressure fluctuations(24h DBPSD),BP rhythm(dipper,nondipper),early morning systolic BP,early morning diastolic BP).According to the 24 h urinary sodium level to assess salt intake,patients were divided into three groups,namely,low urinary sodium group: urinary sodium ≤ 100 mmol / 24 h(salt intake ≤ 6 g / d),medium urinary sodium group: 100 mmol / 24 h < urinary sodium ≤ 200 mmol / 24 h(6 g / d < salt intake ≤ 12 g / d),and high urinary sodium group: urinary sodium > 200 mmol / 24 h(salt intake > 6 g / d).Ambulatory blood pressure monitoring results as well as gender,age,disease duration,body mass index(BMI),blood lipids,renal function test,electrolytes,fasting blood glucose(FBG),glycated hemoglobin A1c%(Hb A1c%),left ventricular ejection fraction(LVEF),left ventricular mass index(LVMI),relative wall thickness(RWT),medication use were analyzed among the three groups,and further correlation analysis,multiple liner regression and binary logistic regression were applied to explore the relationship between ambulatory blood pressure monitoring results and 24 h urinary sodium.Result:(1)The average urinary sodium of 370 patients was 159.1mmol/24 h.Among the patients,208 were males and 162 were females,with a male to female ratio of1.28:1.Compared with the medium and low urinary sodium groups,patients in the high urinary sodium group had a shorter duration of hypertension;were more often men;had a larger BMI;were more dyslipidemic,and had higher 24-h ambulatory BP(including24h SBP,24 h DBP,d SBP,d DBP,n SBP,n DBP,24 h MAP,24 h HR,systolic BP load,diastolic BP load,nondipper rhythm occupancy,early morning systolic BP,early morning diastolic BP)(P < 0.05).However,there were no significant differences in age,office systolic and diastolic blood pressure,renal function test,electrolytes,FBG,Hb A1c%,LVEF,LVMI,RWT,and blood pressure variability among the three groups(P > 0.05).(2)There were no significant differences in the use of antihypertensive drugs including angiotensin-converting enzyme inhibitors/angiotensin receptor antagonists,calcium channel blockers,beta blockers,diuretics and other antihypertensive agents among the three groups(P > 0.05).There was no significant difference in the number of antihypertensive medications used per person(P > 0.05).(3)Correlation analysis showed that 24 h SBP,24 h DBP,d SBP,d DBP,n SBP,n DBP,systolic BP load,diastolic BP load,24 h MAP,24 h HR,early morning systolic BP,early morning diastolic BP were positively correlated with 24-hour urine sodium.Among other factors,triglycerides(TG)and BMI were positively correlated with 24-h urinary sodium,while high-density lipoprotein cholesterol(HDL-C)and disease duration were negatively correlated with 24-h urinary sodium.Multiple linear regression analysis showed that 24-h urine sodium was a significant influencing factor of 24 h SBP,24 h DBP,d SBP,d DBP,n SBP,n DBP.Binary logistic regression showed that after adjustment for age、gender、duration of illness、presence of diabetes、BMI、LVMI、creatinine and number of antihypertensive medications,increased 24-hour urinary sodium is independently associated with the nondipper of blood pressure.After adjustment for age 、 sex 、 duration of illness 、 presence of diabetes 、 Fasting blood glucose、BMI、LVMI、creatinine and number of antihypertensive medications,increased24-hour urinary sodium was independently associated with the development of early morning hypertension.Conclusion: 24-hour urine sodium is positively correlated with ambulatory blood pressure in patients with essential hypertension and Increased 24-hour urine sodium can increase the risk of blood pressure circadian rhythm disappearance and morning blood pressure rise in patients with essential hypertension.