Association between serum alkaline phosphatase and C-reactive protein in the United States National Health and Nutrition Examination Survey 2005–2006

Abstract

Alkaline phosphatase (ALP) is a widely used marker for skeletal and hepatobiliary disorders, but its activity is also increased in atherosclerosis and peripheral vascular disease. It is an inflammatory marker like C-reactive protein (CRP). We therefore analyzed its relationship with CRP in the United States National Health and Nutrition Examination Survey (NHANES) 2005-2006. The analysis included 4155 men and non-pregnant women over the age of 20 years. The relationship between log-transformed ALP and plasma CRP was analyzed using univariate and multivariate models. ALP activity was significantly correlated with age, waist circumference, body mass index, blood pressure, exercise, alcohol, triglycerides, and other liver enzymes after adjusting for age, gender and ethnicity (p<0.001). ALP was significantly associated with a higher frequency of cardiovascular disease (p=0.02), hypertension (p=0.01) hypercholesterolemia (p=0.04), and diabetes (p=0.02). Compared to the lowest quartile of ALP, the adjusted odds ratio (OR) associated with the highest quartile were 1.9 [95% confidence intervals (CI) 1.1-3.5], 1.6 (95% CI 1.0-2.5), 1.5 (95% CI 1.1-2.1) and 1.7 (95% CI 1.0-2.4) for cardiovascular disease, hypertension, hypercholesterolemia, and diabetes, respectively. In multivariate analysis, log ALP was an independent predictor of log CRP (p=1.0x10(-6)). A multivariate model that included log ALP, ethnicity, glycohemoglobin, waist circumference, albumin, apolipoprotein B, gamma-glutamyltransferase and uric acid explained 40% of the variance in log CRP. ALP is a marker of cardiometabolic risk, but it needs to be tested as part of a multivariate model in prospective studies.