High serum vitamin D protects against renal dysfunction due to cadmium exposure

High serum levels of 25-hydroxyvitamin D (25(OH)D) appear to reduce the risk of renal tubular dysfunction in individuals exposed to cadmium, a recent study has shown.

The study included 133 adults born in two cadmium-polluted areas and one control area. Cadmium levels in urine (UCd) and blood (BCd) were measured, along with urinary β2Microglobulin (UBMG), urinary creatinine (UCr), urinary retinol binding protein (URBP) and serum 25(OH)D.

There was a significant and inverse association between serum 25(OH)D and UBMG and URBP (p<0.05). Participants with serum 25(OH)D levels ≥40 ng/mL were less likely to have renal dysfunction when either UBMG (odds ratio [OR], 0.20; 95 percent CI, 0.1–0.8) or URBP (OR, 0.28; 0.1–1.1) was used as indicators. Serum 25(OH)D <30 ng/mL was used as reference.

A similar trend was observed when analysis was restricted to participants with high UCd or BCd concentrations.

Using UBMG as a marker, researchers showed that those with UCd ≥3.0 µg/g Cr but serum 25(OH)D ≥40 ng/mL had significantly lower risks of renal dysfunction (OR, 0.23; 0.1–0.9). In participants with BCd ≥2.0 µg/L, high serum levels of 25(OH)D also correlated significantly with reduced UBMG (OR, 0.19; 0.1–0.8).

The trends for both high-UCd and high-BCd patients were similar when using URBP as an indicator of renal dysfunction, but the effects were not statistically significant.

“[T]he [protective] effects of vitamin D against cadmium-induced renal dysfunction may be due to its role on oxidative stress and inflammatory reaction,” said researchers.