Iranian Journal of Medical Sciences

Document Type : Original Article(s)


1 Endocrinology and Metabolism Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Iran

2 Department of Pathology, School of Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Iran

3 Social Determinants in Health Promotion Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Iran

4 Department of Medical Genetics, School of Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Iran

5 Department of Cellular and Molecular Medicine, School of Medicine, University of Ottawa, Ottawa, Canada

6 Department of Pharmacology, School of Pharmacy, Eastern Mediterranean University, Famagusta, North Cyprus, via Mersin 10, Turkey



Background: Elevated low-density lipoprotein cholesterol (LDL-C) is a significant risk factor for cardiovascular diseases. LDL-C can be directly measured using various methods, but this requires expensive equipment. Currently, clinical laboratories estimate LDL-C based on Friedewald’s formula (FF). We aimed to develop a modified formula based on directly measured LDL-C (D-LDL-C) values in a large population in Southern Iran and compare the results with various other estimation formulas.
Methods: The participants of this cross-sectional study were adults aged >18 years living in Southern Iran. Blood samples from 15,200 individuals were collected, and the measured lipid parameters were randomly divided into training (n=10,184) and validation (n=5,016) datasets. A new formula was developed using a linear regression model, and its accuracy was validated. Pearson’s correlation and Cohen’s kappa were used to determin the relationship between D-LDL-C and calculated LDL-C (C-LDL-C).
Results: The developed formula for the estimation of LDL-C was 0.857 total cholesterol (TC)-0.915 high-density lipoprotein cholesterol (HDL-C)-0.115 triglycerides (TG). Based on our proposed formula, for TG<150 and TG≥150 mg/dL, there was a significant correlation between mean values of D-LDL-C and C-LDL-C (r=0.985 and r=0.974, respectively). Compared to other formulas, C-LDL-C obtained from the proposed formula had the highest correlation with D-LDL-C. The agreement between D-LDL-C and C-LDL-C for TC<200, 200-239, and ≥240 mg/dL was 80.8%, 63.2%, and 67.4%, respectively, indicating a higher level of agreement than other formulas.
Conclusion: The new formula appears to be more accurate than FF when applied to the population of Southern Iran.


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