LDL cholesterol estimation using the Anandarajaʹs and Friedewaldʹs formulas in schizophrenic patients treated with antipsychotic drugs

Objectives The use of new antipsychotic drugs is associated with an increased risk of diabetes and metabolic syndrome, and the routine monitoring of blood lipids during treatment has been recommended. Recently, a new formula for the estimation of low-density lipoprotein (LDL) cholesterol from total cholesterol and triglycerides has been proposed by Anandaraja et al. (Int J Cardiol 2005; 102: 117), and the aim of our study was its evaluation in schizophrenic patients treated with antipsychotic drugs. Materials and methods In 487 serum samples from schizophrenic patients treated with clozapine in polytherapy, the concentrations of LDL cholesterol were determined by agar gel electrophoresis and the formula of Friedewald et al. (Clin Chem 1972; 18: 499), and compared with the results of the Anandarajaʹs formula. Results A higher correlation and lower error of the estimate of the electrophoresis results was found with those of Friedewald (r = 0.940, ma68 = 0.17 mmol/L) than those of Anandaraja (r = 0.811, ma68 = 0.31 mmol/L). Similar results were obtained on making a dichotomy of the patients with and without metabolic syndrome lipid profile. A highly significant correlation was found between the high-density lipoprotein (HDL) cholesterol levels and the Anandaraja/Electrophoresis (r = 0.817, p < 0.001) and Anandaraja/Friedewald (r = 0.977, p < 0.001) ratios. Conclusions According to our data, Anandarajaʹs formula tends towards an overestimation or underestimation of LDL cholesterol levels, depending on whether the HDL cholesterol levels are high or low, which may be clinically significant. These results do not support the proposed better accuracy of the Anandarajaʹs than the Friedewaldʹs formula.