Hispanics with chronic kidney disease (CKD) and low vitamin D levels respond worse to ergocalciferol therapy than Caucasians, data show.

Researchers led by James Wetmore, MD, of the University of Kansas Medical Center in Kansas City, retrospectively analyzed data from 157 Hispanic and 27 Caucasian CKD patients not on dialysis. Low levels of 25-hydroxyvitamin D—25(OH)D—were found in 89.4% of Hispanics compared with 61.4% of Caucasians, despite similar degrees of CKD, according to an online report in International Urology and Nephrology.

Despite treatment with ergocalciferol in accordance with guidelines from the Kidney Disease Outcomes Quality Initiative (KDOQI), 85.5% of treated Hispanics and 66.7% of treated Caucasians remained vitamin D deficient. Both Hispanics and Caucasians had significant increases in 25(OH)D levels, but the absolute changes were modest (5.0 and 8.0 ng/mL, respectively). The increase observed in Caucasians was significantly greater than in Hispanics, the study showed. Hispanic ethnicity remained independently associated with poorer treatment response even after adjusting for other factors.

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“Our findings suggest that the KDOQI protocol provides inadequate 25(OH)D repletion in many patients with CKD and that alternative approaches may be required,” the authors noted.

They also observed that their findings “may have implications for other darker-skinned populations, even in solar-rich environments.”

Study participants were drawn from a community nephrology practice in a part of southern Texas that had 226 and 205 clear sunny days in 2006 and 2007, respectively, and is considered a “sunny area” by the U.S. National Weather Center.

The authors acknowledged some important study limitations, including the retrospective nature of the study and the relatively small number of Caucasians, which the investigators noted was “a reality of our practice demography.”