Alkaline phosphatase and arterial structure and function in hypertensive African men: the SABPA study

Background: Vascular calcification is believed to be due to the conversion of vascular smooth muscle cells into osteoblast-like cells and is associated with mortality. Since hypertension and related mortality in Africans is a concern, we investigated associations between a marker of osteoblastic activity, alkaline phosphatase (ALP), and measures of arterial structure and function in hypertensive African men. Methods: This study included 79 participants. We conducted 24 h ambulatory blood pressure and carotid intima–media thickness (cIMT) measurements. cIMT was obtained with an intra-observer variability of 0.04 mm and the cross-sectional wall area (CSWA) was calculated. ALP was measured in serum. Results: ALP was within its reference range (101.6 vs. 30.0–120.0 U/L), however cIMT was higher when this group was stratified and compared to gender and age-specific reference values. In univariate and partial regressions, and confirmed with multiple regression analyses, 24 h systolic blood pressure (β=0.289, p=0.018), 24 h pulse pressure (β=0.387, p=0.002), but not 24 h diastolic blood pressure (β=0.073, p=0.58), were positively associated with ALP. In addition, mean cIMT (β=0.322, p=0.006) and CSWA (β=0.285, p=0.013) also correlated positively with ALP after adjusting for significant covariates, and after excluding participants with diabetes, renal dysfunction or a HIV positive status. Conclusion: Serum alkaline phosphatase is adversely associated with measures of arterial structure and function in hypertensive African men