Serum calcium and phosphorus associate with the occurrence and severity of angiographically documented coronary heart disease, possibly through correlation with atherogenic (apo) lipoproteins

The associations of serum calcium and phosphorus concentrations as well as other cardiovascular risk factors were investigated in relation to the existence and severity of coronary heart disease (CHD) in 260 clinically stable, angiographically defined CHD patients aged 40-70 years. The subjects were classified as CHD+ cases if one or more coronary arteries had a significant stenosis (>= 70%) and CHD- controls if there was no stenosis (<= 10%) in any artery. The severity of coronary occlusion was scored on the basis of the number and extent of lesions, as normal, mild, moderate or severe. Fasting serum concentrations of electrolytes, lipids and (apo)lipoproteins were determined. The concentrations of serum total calcium (2.41 +/- 0.14 vs. 2.33 +/- 0.22 mmol/L, p <= 0.05), albumin-corrected calcium (2.33 +/- 0.25 vs. 2.23 +/- 0.25 mmol/L, p <= 0.01), phosphorus (1.32 +/- 0.21 vs. 1.25 +/- 0.17 mmol/L, p <= 0.007) and the ion product of calcium and phosphorus (3.16 +/- 0.58 vs. 2.91 +/- 0.50, p <= 0.0001) were significantly higher in the CHD+ compared to the CHD- group. Patients with CHD compared with controls had increased serum levels of triglyceride, total cholesterol, low-density lipoprotein-cholesterol (LDL-C), apolipoprotein B (apoB), lipoprotein(a) [Lp(a)] and decreased serum levels of high-density lipoprotein (HDL)-C and apoAI. Multiple logistic regression analysis showed strong and significant association between diabetes mellitus (odds ratio, ORs5.24, p <= 0.0001), male gender (OR=8.84, p <= 0.0001), Lp(a) (OR=1.014, p <= 0.006), hypertension (OR=2.61, p <= 0.02), apoB (OR=1.031, p <= 0.001), age (OR=1.055, p <= 0.003), phosphorus (OR=2.438, p <= 0.01), albumin-adjusted calcium (OR=1.532, p <= 0.05), cholesterol (OR=1.009, p <= 0.05) and the occurrence of CHD. On the basis of bivariate correlation analysis, serum-adjusted calcium was positively correlated with the levels of cholesterol (r=0.285, p <= 0.0001), LDL-C (r=0.320, p <= 0.0001), Lp(a) (r=0.173, p <= 0.005), apoB (r=0.237, p <= 0.0001), LDL-C/apoB ratio (r=0.180, p=0.007), apoAI (r=0.181, p <= 0.003) and inversely to HDL-C (r=-0.146, p <= 0.02) and HDL-C/apoAI ratio (r=-0.263, p <= 0.0001). Serum phosphorus concentration was a significant correlate of triglyceride (r=0.199, p <= 0.001) and Lp(a) (r=0.129, p <= 0.04). The results demonstrated that serum calcium and phosphorus are associated with the prevalence and severity of CHD, probably through correlation with atherogenic lipids and (apo) lipoproteins. Serum calcium and phosphorus and their ion product were also independent risk factors for CHD.