Preliminary study on serum levels of 1,25-dihydroxyvitamin D and 25-hydroxyvitamin D in cadmium-induced renal tubular dysfunction.

Serum 1,25-dihydroxyvitamin D [1,25(OH)2D] and 25-hydroxyvitamin D [25(OH)D] were measured in 7 women living in a cadmium-polluted area in Toyama, Japan. Despite the fact that these subjects had severe proximal renal tubular dysfunction showing increased fractional excretion of beta 2-microglobulin (FE beta 2-m) ranging from 9.7-49.1% with a mean of 30.7%, the levels of serum 1,25(OH)2D, which is produced in the proximal tubules, were within the normal range in 6 subjects. Significant correlations were found between 1,25(OH)2D and creatinine clearance (r = 0.802, P less than 0.05), and FE beta 2-m (r = -0.829, P less than 0.05), respectively. These results suggest that renal production of 1,25(OH)2D decreases with progression of cadmium-induced renal tubular dysfunction.