Therapeutic Effect of Sodium Intake Reduction in Treatment Resistant Hypertension

The study consists of 3 phases. The first phase is to exclude pseudo-resistant hypertension by improving compliance to antihypertensive medications. Patients should visit with a prescribed antihypertensive drugs to calculate compliance to medication. If patient has compliance to medication \>= 85% \[= (the number of pills dispensed - the number of pills counted) / the number of pills expected to have been taken (calculated by multiplying the daily dose by the number of days since the date dispensed)\], ambulatory blood pressure will be measured. If the patient had compliance to medication \>= 85%, and daytime ambulatory blood pressure \>=135/85 mmHg, he will be entered into first phase of treatment. If patient had compliance to medication \<85%, patients will be asked to enhance medication adherence to 85% or more, and revisit after 1 months. In the first phase of treatment, dose of current antihypertensive medications (diuretics should be included) will be escalated to optimal doses. Three or more classes of antihypertensive drugs should be prescribed, and educate to keep compliance to medication \>=85%. The duration of second phase of treatment is 2 months. After start of first phase, there is a monitoring visit monitoring of adverse drug reaction of diuretics for safety. If there is adverse drug reaction, the dose of suspected drug will be decreased. After 2 months of treatment, if daytime ambulatory blood pressure is \>= 135/85 mmHg with compliance to medication \>=85%, the patients will be entered into second phase of treatment. In the second phase of treatment, patients will be randomly assigned to receive either education of exercise or education of exercise and low sodium diet (intensive education with education materials). To the patients assigned to exercise education, detailed training of diet control using educational materials will not be provided. The patients will be blinded to educational group assignments. The duration of second phase of treatment is 1 month. Before start and after completion of second phase of treatment, the amount of sodium intake will be measured by 24-hour urine sodium excretion.