Serum total sialic acid and lipid-associated sialic acid in normal individuals and patients with myocardial infarction, and their relationship to acute phase proteins.

Serum total sialic acid (TSA) has gained medical interest, particularly as a cardiovascular risk factor and it has been hypothesized that serum levels relate to serum acute phase proteins, some of which are sialylated. We assayed serum TSA and also lipid associated sialic acid (LASA) in 50 normal individuals (24 male) and 15 subjects (12 male) who had experienced a myocardial infarct. The mean serum TSA in the normal individuals was 2.05 SD 0.38 mmol/L (range 1.16-2.74) and the mean serum LASA was 0.70 SD 0.19 mmol/L (range 0.23-1.03). We also measured five serum acute phase proteins and found a good correlation between these and serum TSA: C-reactive protein, r = 0.52, P < 0.001, alpha-1-antichymotrypsin, r = 0.79, P < 0.0001, alpha-2-macroglobulin, r = 0.38, P < 0.01 and alpha-1-acid glycoprotein, r = 0.32, P < 0.05. A significant correlation between plasma TSA and plasma C-reactive protein (r = 0.47, P < 0.04) and also fibrinogen (r = 0.53, P < 0.04) was noted on day one following the myocardial infarction, whereas a significant correlation between plasma TSA and plasma alpha-1-antichymotrypsin (r = 0.51, P < 0.03) and also plasma alpha-1-acid glycoprotein (r = 0.64, P < 0.05) was found on day two following the infarction. Thus it would seem that serum TSA is at least in part related to some of the acute phase proteins in both healthy individuals and those having had a myocardial infarction.