Visit 1 Enrollment Measurements Week 1, Day 1, include the following measurements: Biometric measurements: Body Weight, confirmation of hypertension by 24-h ABPM Urine studies: start 24 hour Urine collection, safety laboratory evaluations: bone morphogenetic protein , document concomitant medications, and adverse reactions. Visit 1 Enrollment Measurements Week 1 Day 2 the subject will return the 24-hour urine collection and the 24 hour ABPM will be removed. The study medication chlorthalidone will be started. The subject will take study medication for 3 weeks before returning for the next study visit: Visit 2 (Week 3) Day 1 . A three day window will be allowed.