Effects of treatment with an angiotensin 2 receptor blocker and/or vitamin D3 on parathyroid hormone and aldosterone: A randomized, placebo‐controlled trial.

Summary: Objective: Emerging evidence supports a positive, bidirectional and clinical relevant interaction between parathyroid hormone (PTH) and the renin‐angiotensin‐aldosterone‐system (RAAS). A beneficial effect of the widely used RAAS inhibitors might include a PTH‐lowering effect, as high PTH levels may be harmful to cardiovascular health. We aimed to investigate whether PTH levels are lowered by short‐term treatment with an angiotensin 2 receptor blocker (valsartan) independently of coadministration of vitamin D3. Secondary end‐points included effects on blood pressure, cardiac conduction and concentrations of renin and aldosterone. Design and Methods: In a double‐blind placebo‐controlled trial, we included 81 otherwise healthy postmenopausal women with high PTH levels (>6.9 pmol/L) and vitamin D insufficiency (25(OH)D < 50 nmol/L). Participants received 2 weeks of treatment with valsartan 80 mg/d, vitamin D3 70 μg/d, valsartan plus vitamin D3 or double placebo. Results: Valsartan treatment did not affect plasma PTH, although treatment reduced diastolic blood pressure (P = .01) and the aldosterone/renin ratio (P < .001). We found no associations between calciotropic hormones and RAAS markers. Vitamin D3 supplementation reduced PTH by 3.4% (25th, 75th −9.0 to 8.7) compared to a 7.1% increase (25th, 75th −2.4 to 30.9) in the placebo group (P = .01), but did not affect blood pressure, cardiac conduction or concentrations of renin and aldosterone. Conclusions: Independently of vitamin D3, short‐term valsartan treatment did not reduce PTH. Vitamin D3 reduced PTH but did not affect blood pressure, cardiac conduction or the RAAS. The study does not support a direct association between PTH and aldosterone or a blood pressure‐lowering effect of vitamin D3. [ABSTRACT FROM AUTHOR]