Development and validation of an enzymatic method for total cholesterol analysis using whole blood spots

Background: High serum cholesterol represents a risk factor for cardiovascular disease. This study aims to quantify total cholesterol in dried blood spot (DBS) by direct enzymatic method. Methods: Three hundred seventeen blood samples with serum cholesterol level ranging from 81 to 337 mg/dl were collected. DBS were manually prepared, cholesterol was extracted using methanol and analyzed by a manual enzymatic method. DBS cholesterol method was validated for imprecision and extraction efficacy. DBS cholesterol values were correlated (training test) with serum values measured by automated enzymatic method (reference method). The obtained correlation was used for predicting serum cholesterol from DBS analysis of a new sample group (validation test, n = 58). Results: Within-day and between-day coefficient of variation (CV%) were lower than 7.69 and 6.32, respectively. Residual cholesterol in DBS after extraction was 16%. DBS cholesterol and serum cholesterol showed a linear correlation (slope = 0.5217; r = 0.9139) and a bias of -28%. Furthermore, DBS cholesterol values of validation test (n = 58), converted using the training test correlation, were not statistically different compared to the corresponding plasma values (P = 0.9487), and the comparison by Passing and Bablok showed a linear regression with a slope of 1.068 (r = 0.611) and a bias of -0.22%. Conclusions: The results show that this enzymatic method is suitable to analyze cholesterol in DBS and it could be automated and used for population screening of total blood cholesterol