Objectives: Low-normal thyroid function within the euthyroid range may influence plasma lipoprotein levels. Associations between variation in thyroid function and pre-beta-high density lipoproteins (pre-beta-HDL), i.e. lipid-poor or lipid free HDL particles that act as initial acceptor of cell-derived cholesterol, are unknown. We determined relationships of plasma pre-beta-HDL with thyroid function in euthyroid subjects with and without type 2 diabetes mellitus (T2DM).
Design and Subjects: TSH, free T4, plasma (apo)lipoproteins, pre-beta-HDL, pre-beta-HDL formation (pre-beta-HDL generation during incubation with lecithin:cholesterol acyltransferase being inhibited) and phospholipid transfer protein (PLTP) activity were measured in fasting plasma from 72 T2DM and 82 non-diabetic subjects.
Results: TSH was similar and free T4 was slightly higher (P <0.05) in T2DM vs. non-diabetic subjects. HDL cholesterol and apoA-I were lower, whereas pre-beta-HDL (expressed as % of apoA-I), triglycerides and PLTP activity were higher in T2DM (P <0.05 to P <0.001). In T2DM, pre-beta-HDL formation (in apoA-I concentration and in % of apoA-I) was positively related to free T4, PLTP activity, total cholesterol and triglycerides (P<0.05 for each). Multivariable linear regression analyses, adjusted for age, sex, PLTP activity, total cholesterol and triglycerides, demonstrated that pre-beta-HDL formation was positively related to free T4 (in apoA-I concentration: beta = 0.278, P = 0.014; in % of apoA-I: beta = 0.343, P = 0.003) in T2DM, but not in non-diabetic subjects (both P>0.30; interaction terms: both P<0.05).
Conclusions: Variations in thyroid function within the euthyroid range may influence the metabolism of pre-beta-HDL in T2DM. (C) 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.
- High density lipoproteins
- Phospholipid transfer protein
- Thyroid function
- Type 2 diabetes mellitus
- CHOLESTERYL ESTER TRANSFER
- NORMAL THYROID-FUNCTION
- INTIMA MEDIA THICKNESS
- TRANSFER PROTEIN
- PRE-BETA(1) HDL
- REFERENCE RANGE