Higher vitamin D levels in hypertensive patients, especially those without diabetes, may be at lower risk for new-onset proteinuria, new study findings suggest.

In a large prospective cohort study that include 1655 Chinese patients with hypertension, investigators found an inverse association between baseline plasma levels of 25-hydroxyvitamin D3 (25[OH]D3) and new-onset proteinuria. After adjusting for age, sex, body mass index, and other variables, patients in the third and fourth quartiles of 25(OH)D3 levels (17.8 ng/mL or higher) had significant 55% decreased odds of new-onset proteinuria compared with those in the first quartile (less than 13.1 ng/mL), a team led by Xianhui Qin, MD, PhD, of Nanfang Hospital, Southern Medical University, Guangzhou, China, concluded in the Journal of Renal Nutrition. Each standard deviation (SD) increment in 25(OH)D3 was associated with significant 30% decreased odds of new-onset proteinuria.

“If further confirmed, maintaining optimal 25(OH)D3 concentrations may be considered an adjuvant nutritional strategy for the prevention and treatment of proteinuria in a general hypertensive population,” the authors wrote.

The inverse association between 25(OH)D3 levels and new-onset proteinuria was strongest among patients without diabetes. In this group, each 1 SD increment in 25(OH)D3 was associated with significant 43% decreased odds of new-onset proteinuria. Among diabetics, however, each 1 SD increment in 25(OH)D3 was associated with nonsignificant 48% increased odds of new-onset proteinuria.


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The authors noted that possible mechanisms by which diabetes causes proteinuria may include endothelial dysfunction, immune-mediated inflammatory processes, and activation of the intrarenal renin-angiotensin-aldosterone system. “We hypothesized that because diabetes and lower 25(OH)D3 share some common mechanisms associated with the risk of new-onset proteinuria, the detrimental effects of diabetes may attenuate the potential protective effects of higher 25(OH)D3 levels on incident proteinuria,” they wrote.

The study was a post hoc analysis of the renal substudy of the China Stroke Primary Prevention Trial. The analysis included patients who at baseline did not have proteinuria and had an estimated glomerular filtration rate of 60 mL/min/1.73 m2 or higher. The investigators defined new-onset proteinuria as a urine dipstick reading of 1+ or higher at the exit visit.

Reference

Zhou H, Li H, He P, et al. Plasma 25-hydroxyvitamin D3 concentrations and risk of new-onset proteinuria in patients with hypertension. Published online December 9, 2020. J Ren Nutr.  doi:10.1053/j.jrn.2020.09.005