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 hypertensive African men. We conducted 24h ambulatory blood pressure and carotid intima-media thickness (cIMT) measurements. The 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 compared to gender and age-specific reference values i.e., 25 to 40 years (0.63 vs. 0.43–0.53 mm), 40 to 50 years (0.71 vs. 0.50–0.61 mm) and older than 50 years (0.84 vs. 0.53–0.70 mm). In single and partial regressions, and confirmed with multiple regression analyses, 24h systolic blood pressure (R²=0.304, β=0.299, p=0.011), 24h pulse pressure (R²=0.318, β=0.398, p<0.001), but not 24h diastolic blood pressure (R²=0.164, β=0.078, p=0.54), were positively associated with ALP. In addition, cIMT (R²=0.393, β=0.302, p=0.008) and CSWA (R²=0.409, β=0.255, p=0.023) also correlated positively with ALP after adjusting for significant covariates, and after excluding participants with diabetes and renal dysfunction.

Conclusion: Serum alkaline phosphatase in hypertensive African men is adversely associated with measures of arterial structure and function, independent of diabetes and renal dysfunction.