Lipids, lipoproteins and apolipoproteins among turks, and impact on coronary heart disease

Abstract

Serum concentrations of lipids, lipoproteins, and apolipoproteins (apo) among Turkish adults have been reviewed in this paper whereby stratification by gender and age groups was provided, together with a description of differences by geographic regions and urban-rural areas. Most of the knowledge was derived from the prospective population-based Turkish Adult Risk Factor (TEKHARF) Study, having already a 13 years' follow-up, but data contributed by the Turkish Heart Study were also outlined. In the setting of a prevalence of metabolic syndrome in 3 out of 8 Turkish adults, Turks have low levels of total cholesterol (mean 185 mg/dl), LDL-cholesterol (mean 116 mg/dl), and HDL-cholesterol (mean 37 and 45 mg/dl in men and women). The latter is associated with comparatively high concentrations of triglycerides (mean 143 mg/dl) and of apo B (mean 115 mg/dl). This suggests that small, dense LDL particles (pattern B) prevail in this population though studies are missing in this regard. In line with this notion are the high levels of total/HDL cholesterol ratio (mean 5.3 in men, 4.5 in women). It is remarkable that women exhibit identical LDL-cholesterol levels as men. The lipid parameter that has changed strikingly since 1990 are the rising triglycerides, accompanying a similar trend in (abdominal) obesity. On multivariate analysis, the best independent lipid predictor of coronary heart disease (CHD) risk among Turks is the TC/HDL-C ratio. A 2-unit increment of TC/HDL-C adds an excess of 68% to both the nonfatal and fatal CHD event risk. When ratios of = or >5.5 in men and = or >5 in women are considered as high risk, slightly more than one-third of Turkish adults, corresponding to 12 million adults, are included by these criteria into high-risk group. A major portion of Turkish adults harbouring total cholesterol concentrations in the 180-200 mg/dl range are at high risk, and we stress the opinion that the upper normal limit of total cholesterol be reduced to 180 mg/dl in Turks, at least in men.