Quick one today: interesting article in a recent issue of C-JASN by Shantouf et al that demonstrates a link between serum alkaline phosphatase levels and vascular calcification in patients with ESRD. Briefly, the study examined 137 randomly-selected ESRD patients and assessed both their serum alkaline phosphatase level as well as their coronary artery calcification score (CACS), which is determined by CT scan. The investigators discovered that having a serum ALKP > 120 IU/L resulted in a multivariate odd ratio of 5.0 (with a confidence interval 1.6 - 16.3 and a p = .007, seemingly solid numbers). The authors suggest that perhaps ALKP could be used as a surrogate marker for risk of CVD and potentially used to follow positive response to cardiovascular therapies.
There are of course several potential reasons for alkaline phosphatase to be elevated in this patient population. High turnover bone disease (e.g., osteitis fibrosa cystica) is present frequently in the ESRD population. The authors also suggest that perhaps alkaline phosphatase is release in response to vascular damage, where it could potentially play a role in limiting vascular damage. Alkaline phosphatase works by hydrolyzing phosphate groups from a variety of biological compounds.