Comparison of two methods [precipitation manual and fully automated enzymatic] for the analysis of HDL and LDL cholesterol

To compare accuracy and throughput time for the measurement of HDL and LDL cholesterol by manual precipitation and fully automated enzymatic methods. Fifty, serum samples collected over a 4 months period [February - May 2004] were analyzed for HDL and LDL cholesterol by two different methods i.e. precipitation manual and automatic enzymatic method in the section of chemical pathology, Department of Pathology and Microbiology, Aga Khan University Hospital, Karachi Pakistan. The mean standard deviation for HDL Cholesterol by precipitation method and automated method were 43.12'8.97mg/dl and 43.86'10.34mg/dl respectively [p-value = 0.301]. The mean standard deviation for LDL cholesterol by precipitation method and automated method were 111.76'25.57mg/dl and 111.8'28.41mg/dl respectively [p-value = 0.981]. The calculated "t" and "F" value for HDL-C was 0.0172 and 0.75 respectively, and calculated "t" and "F" values for LDL-C were 0.047 and 0.809 respectively. Average time for manual method was 45 minutes and automation 20 minutes. Both the precipitation [manual] method and the automated method provide reliable, precise and accurate results. In both the methods "t" and "F" values were less than critical. Automated method provide high throughput and are less labor intensive. The choice of method can depend on laboratory facilities and workload

To compare the total cholestrol and HDL cholestrol before and after ultracentrifugation in lipemic samples

It is an everyday routine in laboratories to encounter interference in the analysis of lipids. These likely interferences [hemolysis, icterus and lipemia] are countered by asking physicians and patients to send fresh and properly collected samples. At the Aga Khan University [AKU] Laboratory, we receive 2-3 lipemic/turbid samples per day. Previously it was our departmental policy to advise these patients to go for lipoprotein electrophoresis, which though accurate was time consuming and not cost effective. We therefore studied ultra centrifugation/airfuge as an alternate method to clear lipid interference and provide accurate, reliable and cost effective results. Daily 2-3 grossly turbid samples are identified on the lipid bench, 48 samples were received in 4 months [February to May 2004]. These samples were analyzed for total cholesterol [TC] and High Density Lipoprotein -Cholesterol [HDL-C] before and after ultra centrifugation/airfuge. There was a positive correlation between the lipemia and the false high TC and HDL-C. The mean TC and HDL-C before ultra centrifugation were 263.06 mg/dl and 39.42 mg/dl respectively and after centrifugation these became 191.77 mg/ dl and 33.06 mg/dl. P value showed a significant difference in both results. This study suggests that the removal of turbidity by ultra centrifugation/airfuge is cost effective, less time consuming and provides accurate reliable results of TC and HDL-C in patients with lipemia interference