Validation of the Friedewald formula for the determination of low-density lipoprotein cholesterol in renal transplant recipients

In large patient populations, it has been established that calculated (c) and measured (m) plasma levels of low-density lipoprotein cholesterol (LDL-C) were comparable, but this issue is not known to be tested in renal transplant recipients (RTRs). Herein we aimed to compare the plasma levels of LDL-C that was calculated by Friedewald formula (FF) and direct measurement in RTRs. Methods: LDL-C was measured by direct method and by FF in 193 fasting venous blood samples obtained from 103 RTRs. Patients had triglyceride (TG) levels < 400 mg/dL. Patients were treated with prednisolone, calcineurin inhibitors (CNIs), and/or sirolimus and everolimus. Results: The mean plasma levels of LDL-C for calculated and direct measurement were 100.81 +/- 32.79 mg/dL and 107.82 +/- 33.23 mg/dL, respectively (p < 0.01). The differences between cLDL-C and mLDL-C were similar according to usage of angiotensin receptor blockers (ARB)/angiotensin-converting enzyme inhibitors (ACEI), CNI, or mammalian target of rapamycin inhibitor (mTOR), tacrolimus or cyclosporine, and serum creatinine levels. mLDL-C and cLDL (FF) were highly correlated (r = 0.977). The mLDL-C level was calculated by following formula: LDL-C = 8.018 + (0.99 x FF cLDL-C) and the mean difference was 0 for last formula. Conclusion: The LDL-C can be calculated by the following formula: LDL-C = 8.018 + (0.99 x FF LDL-C). The coefficient of determination correlation (r) for this regression was 0.977, which indicates that the calculated LDL-C levels can be used in RTRs with TG lower than 400 mg/dL. mLDL-C was significantly higher than cLDL-C. We observed that difference between cLDL-C and mLDL-C levels were not affected by serum creatinine levels and usage of CNIs, sirolimus, everolimus, ACEI, and ARB in RTRs.