Lipoprotein(a) in a High-risk Turkish Population Sample: Distribution and Correlations, with Emphasis on Inverse Relationship to Insulinemia in Men

In a sample of the cohort residing in the Marmara and Central Anatolian regions of the Turkish Adult Risk Factor Study, lipoprotein(a), among other laboratory tests, were determined in 214 subjects comprising a small proportion with low coronary risk. The purpose of this study was to delineate its relationship to cardiovascular risk factors, metabolic syndrome (MS) and coronary heart disease (CHD) among Turkish adults. Diagnosis of MS was based on criteria of the ATP III, that of CHD on the history of angina and Minnesota coding of the resting ECGs. MS was prevalent in 48% and CHD in 23% of the sample. Serum Lp(a) levels were measured by nephelometry; analyses were carried out after log-transformation of the skewed values. In 98 men and 116 women having a mean age of 59.6±12 years, geometric mean values in men and women were 9.6±2.8 mg/dL and 12.1±3 mg/dL (p<0.001). Values were not correlated with age, and in women with any of the 15 risk parameters. In men, though most variables were also not correlated with Lp(a), LDL- (r =0.29) and total cholesterol (r =0.22) exhibited significant positive, and fasting insulin (r =-0.36, p=0.002), waist circumference (r =-0.22) and body mass index (r =-0.26) inverse correlations. Diagnosis of MS tended to be inversely correlated with Lp(a) in men. In multiple linear regression analysis, serum levels of total and LDL cholesterol and triglycerides were significantly associated positively with Lp(a) while gamma glutamyltransferase was so inversely. Logistic regression, adjusted for sex and age, demonstrated no significant association between Lp(a) and CHD. This study supported the observation that Lp(a), the variance of which is known to be overwhelmingly to the apo(a) isoforms, was not related to most conventional risk factors. The interesting observation of an inverse relation between Lp(a) and insulinemia in men (or some men) may be due to a genetic feature which along with the association with CHD likelihood in Turkish adults requires further investigation in the future. (Türk Kardiyol Dern Arş 2004; 32: 82-90)