Reliability of LDL cholesterol estimation (Friedewald, Martin) is not affected by the thyroid metabolism

Objective: The main purpose of the study is to determine whether hypothyroidism and/or hyperthyroidism has any significant effect on the reliability of the LDL-cholesterol (LDL-C) estimation by the Friedewald and the Martin equation.
Design: Comparative Study Material and Methods: 40 patients with newly diagnosed autoimmune hypothyroidism (36 female, 4 male). Comparison of the deviations of the LDL-C assessments by the Friedewald and the Martin equation in a group of non-treated patients in an euthyreotic state.
Results: The deviations in the LDL-C levels estimated by Friedewald or by Martin showed a non-systematic character. The differences in reliability from the measured LDL-C between the individual groups can be explained with the well-known variability of the LDL-C estimation by Friedewald in dependence on the TAG and TC levels. The LDL-C level estimations calculated by the Martin equation were higher than the estimations calculated by Friedewald in 6 instances, in one instance the values were identical.
Conclusion: Systematic effect on the reliability of LDL-Cholesterol estimated either by the Friedewald or the Martin equation by the hyper- or hypofunction of the thyroid gland was not discovered.