Feasibility Of Diet Recall And 24-h Urine Na Measurement In Evaluating Daily Salt Intake And Their Relationship With Blood Pressure

Objective:To evaluate the feasibility of diet recall and 24-h urine Na measurement in evaluating daily salt intake,and to assess relationship between salt intake and blood pressure in Chinese patients with first-ever stroke.Methods:Patients with first-ever stroke in Jingling Hospital were prospectively enrolled between December 2013 and December 2014.Patients who did not start antihypertension treatment within 10 days after the occurrence of st:roke,average blood pressure of 8 to 10 days after the stroke were taken as window period of blood pressure.If patients started treatmen within 10 days,3 days’ blood pressure before the treatment were taken as the window period of blood pressure.During follow up,patients who agreed to collect 24-h urinary sampling were screened and evaluated for study enrolment.Patients’ blood pressure were measured by an experienced doctor and recorded as follow-up blood pressure.All the subjects were trained to collect 24-h urine.Urinary excretion of Na and K were analyzed by flame photometry and creatinine by Jaffe’s procedure.The quantity of sodium,potassium and total energy for each food of diet recall were calculated by using Chinese food composition tables.Sodium:Potassium Ratio(SPR),sodium density and potassium density were also calculated.The correlation between urinary and dietary Na and K was analysed.The association between those indexes and blood pressure were also examined.Results:A total of seventy-six patients provided 24 hours urine samples,but only fifty-five were complete(Three urine samples were contaminated,nine incomplete,another nine tested samples unqualified).Of these 55 patients,the 24-h urine volume(mean±SD)was 1731.8±565.3 ml,24-h urine sodium was 161.3 ± 49.8 mmol,24-h urine potassium was 44.7±14.0 mmol,24-h urine creatinine was 10.3 ± 2.4mmol,sodium:potassium ratio(SPRu)was 4.0 ± 1.7.Of the 55 patients,19 patients provided qualified 24-h diet recall.Daily Na intake assessed by dietary recall was 143.1±42.7mmol.K intake was 39.4 ± 13.5 mmol,daily intake of sodium:potassium ratio(SPRd)was 3.8± 1.1.24-h urinary sodium excretion(24-h salt intake)was associated with the window period of systolic blood pressure(SBP)(r=0.298,p=0.027)and the follow-up diastolic blood pressure(DBP)(r=0.270,p=0.046).Sodium density was associated with the follow-up SBP(r = 0.642,p = 0.003).There existed significant correlationship between K intake evaluated by dietary recall and 24-h urine measurement(r=0.861,p<0.001).The SPR by these two methods was also correlated(r=0.620,p=0.005).No significant coralationship was detected between salt intakes evaluated by dietary recall and 24 urine measurement(r=0.395,P=0.090).Conclusion:Chinese patients with first-ever stroke intaked far more salt than that recommend by WHO and Chinese Guidelines.Diet recall may underevaluate the salt intake in elderly with stroke.Salt intake(sodium)and potassium may associate with blood pressure in stroke patients.