Figure 2

VALIDATE-D study schema : subjects will be screened and then may undergo a medication washout to withdraw interfering anti-hypertensive medications (when applicable). Aim 1: The circulating RAS will be assessed on LS diet before and after randomization to calcitriol/placebo (visits 2 & 5). Aim 2: The renal-vascular tissue-RAS will be assessed on HS diet before and after calcitriol/placebo (visits 3 & 6). Aim 3: All subjects will then receive lisinopril 5 mg/d in addition to calcitriol/placebo to assess the impact of combination therapy (calcitriol + lisinopril vs. placebo + lisinopril) on the renal-vascular tissue-RAS (visits 6 & 8) and proteinuria (visits 6, 8, 13). Serum calcium and phosphate will be monitored weekly throughout the study for safety, at each visit and at designated safety checks (visits 4, 7, 9–12).