Comparative Study of Direct - Measured and Calculated LDL in Clinical Use†
Surachai Rungtanapirom MD*, Boonsong Ongphiphadhanakul MD**, Thanongsak Kiatbamrungpunt MD*, Jongruck Bhakdikul MD*, Sutep Archavanuntakun MD*, Chaisilp Taerakul MD*, Jantana Pongsanguansin MD*, Veeravit Charoenloet MD*, Krisnapong Tansanguan MD*
Affiliation : † This study is granted by The Vejdusit Foundation under the Royal patronage of H.R.H. Princess Kalayaniwatana Kromluangnaradhiwasrajnagarindra * Department of Internal Medicine, Bangkok Hospital Medical Center, Bangkok ** Division of Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok
Objective : Compare DLDL-C and CLDL-C obtained during regular service in hospital.
Material and Method: The study at Bangkok Hospital included 9,285 lipid profiles of different individuals
that contained total cholesterol (TC), triglyceride (TG), HDL cholesterol (HDL-C), and directly-measured (by
homogeneous method) LDL cholesterol (DLDL-C). The population has mean age 45.92 + 12.43 years, 48%
were male. LDL-C values were also calculated by Friedewald equation (CLDL-C). However, it was known to
have limitation when TG > 400 mg/dL.
Results : The DLDL-C is 13.4 + 8.8% higher than CLDL-C. The authors could obtain CLDL-C closer to DLDL-C
in wider TG range, including other explanatory variables in the equation to calculate LDL-C, by these two
equations, DLDL-C = 0.98 TC – 0.84 HDL – 0.12 TG + 0.056 age + 0.071 BMI, and DLDL-C = 0.98 (TC – HDL)
– 0.12 TG + 0.1 age + 2.4 sex + 0.2 BMI.
Conclusion : DM and using lipid-lowering medications had no effect on the correlation of CLCL-C and
DLDL-C.
Keywords : Friedewald equation, LDL measurement, LDL, LDL equation
