Albuminuria is a known risk factor for cardiovascular disease (CVD), chronic kidney disease (CKD) progression, all cause mortality. Inhibition of the renin-angiotension-aldosterone system (RAAS) plays an important role in the reduction of albuminuria and preservation of renal function in patients with CKD and it is known that the daily intakes of sodium have a significant effect on the activity of RAAS. Dietary sodium restriction has been shown to enhances the blood pressure, albuminuria, and renal function preservation. Furthermore, recent study has shown that intensive low-salt dietary education reduces albuminuria in patients with CKD. The average sodium intake of Koreans is 4,791 mg/d, which is higher than other countries. It is difficult for medical staff in Korea to invest enough time in low salt diet.

Recently, the development of health-related applications (apps) has been carried out worldwidely, and researches on lifestyle improvement using apps have been actively studied. However, there is no research yet on whether intensive education using an apps can affect lifestyle habits and thus changes in actual new features. Smartphone apps may provide an alternative to resource-intensive low salt diet-education. Therefore, this study aims to investigate the effect of intensive low salt diet training on the changes of albuminuria using application.

This is an pen-label, case-control, randomized clinical trial.

• Run-in period (8 weeks) : before 8 weeks of study initiation, all of the patients have to stop all RAAS blockers or diuretics and switch to antihypertensive agents of other categories such as calcium channel blockers.
• 0-8 weeks : After run-in period, the patients complete laboratory examination and a dish frequency questionnaire. From 0 weeks, all participants will be prescribed valsartan 80mg per day until the end of study.
• 8-16 weeks : After 8 weeks, the patients will be randomly assigned to receive an low-salt dietary intervention after second laboratory examination.

Usual education : Conventional education at an outpatient clinic Intensive education : Low salt diet education through Smartphone app

The patients in the conventional education group will receive routine CKD education once at an outpatient clinic. Otherwise, the patients in the intensive education group will be trained low salt diet through smartphone app.

Inclusion Criteria:

• Age : 19-65
• Underlying hypertension or antihypertensive medication , or Systolic blood pressure ≧ 140 mmHg or Diastolic blood pressure ≧ 90
• Modification of Diet in Renal Disease study (MDRD) eGFR ≧ 30 ml/min per 1.73m2
• Random urine albumin-to-creatinine ratio ≧ 30 mg/g
• Smartphone ownership

Exclusion Criteria:

• Age under 18 or over 66
• Uncontrolled hypertension (BP>160/110 mmHg)
• Pregnancy within 6 months
• Serum potasium > 5.5 mEq/L
• malignancy
• a diagnosis of CVD (cerebral infarction, hemorrhagic infarction, acute myocardial infarction or unstable angina, coronary angioplasty, or coronary artery bypass surgery) within the last 6 months
• Contraindication to angiotensin II receptor blocker
• life expectancy less than 6 months