title: Correlation of Friedewald's calculated low-density lipoprotein cholesterol levels with direct low-density lipoprotein cholesterol levels in a tertiary care hospital.
abstract: BACKGROUND
  One of the risk factors for the development of coronary heart disease is high low-density lipoprotein (LDL) cholesterol levels. National Cholesterol Education Program ATP III guidelines suggest drug therapy to be considered at LDL-cholesterol levels >130 mg/dl. This makes accurate reporting of LDL cholesterol crucial in the management of Coronary heart disease. Estimation of LDL cholesterol by direct LDL method is accurate, but it is expensive. Hence, We compared Friedewald's calculated LDL values with direct LDL values.
  
  
  OBJECTIVE
  To evaluate the correlation of Friedewalds calculated LDL with direct LDL method.
  
  
  METHODS
  We compared LDL cholesterol measured by Friedewald's formula with direct LDL method in 248 samples between the age group of 20-70 years. Pairedt-test was used to test the difference in LDL concentration obtained by a direct method and Friedewald's formula. The level of significance was taken asP< 0.05. Pearsons correlation formula was used to test the correlation between direct LDL values with Friedewald's formula.
  
  
  RESULTS
  There was no significant difference between the direct LDL values when compared to calculated LDL by Friedewalds formula (P= 0.140). Pearson correlation showed there exists good correlation between direct LDL versus Friedewalds formula (correlation coefficient = 0.98). The correlation between direct LDL versus Friedewalds calculated LDL was best at triglycerides values between 101 and 200 mg/dl.
  
  
  CONCLUSIONS
  This study indicates calculated LDL by Friedewalds equation can be used instead of direct LDL in patients who cannot afford direct LDL method.
authors.affiliation: Department of Biochemistry, Pondicherry Institute of Medical Sciences, Affiliated to Pondicherry University, Puducherry, India.
authors.forename: Sunil Kumar
authors.initials: SK
authors.lastname: Nanda
authors.affiliation: Department of Biochemistry, Pondicherry Institute of Medical Sciences, Affiliated to Pondicherry University, Puducherry, India.
authors.forename: M
authors.initials: M
authors.lastname: Bharathy
authors.affiliation: Department of Biochemistry, Pondicherry Institute of Medical Sciences, Affiliated to Pondicherry University, Puducherry, India.
authors.forename: Asha
authors.initials: A
authors.lastname: Dinakaran
authors.affiliation: Department of Biochemistry, Pondicherry Institute of Medical Sciences, Affiliated to Pondicherry University, Puducherry, India.
authors.forename: Lopamudra
authors.initials: L
authors.lastname: Ray
authors.affiliation: Department of Biostatistics, Pondicherry Institute of Medical Sciences, Affiliated to Pondicherry University, Puducherry, India.
authors.forename: K
authors.initials: K
authors.lastname: Ravichandran
keywords: Coronary heart disease; Friedewalds formula; direct low-density lipoprotein