title: Pre-β-HDL formation relates to high-normal free thyroxine in type 2 diabetes mellitus.
abstract: OBJECTIVE
  Low-normal thyroid function within the euthyroid range may influence plasma lipoprotein levels. Associations between variation in thyroid function and pre-β-high density lipoproteins (pre-β-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-β-HDL with thyroid function in euthyroid subjects with and without type 2 diabetes mellitus (T2DM).
  
  
  METHODS
  TSH, free T4, plasma (apo)lipoproteins, pre-β-HDL, pre-β-HDL formation (pre-β-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-β-HDL (expressed as % of apoA-I), triglycerides and PLTP activity were higher in T2DM (P < 0.05 to P < 0.001). In T2DM, pre-β-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-β-HDL formation was positively related to free T4 (in apoA-I concentration: β = 0.278, P = 0.014; in % of apoA-I: β = 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-β-HDL in T2DM.
authors: University of Groningen and University Medical Center Groningen, The Netherlands.
authors: Lynnda J N
authors: LJ
authors: van Tienhoven-Wind
authors: University of Groningen and University Medical Center Groningen, The Netherlands.
authors: Frank G
authors: FG
authors: Perton
authors: University of Groningen and University Medical Center Groningen, The Netherlands. Electronic address: r.p.f.dullaart@umcg.nl.
authors: Robin P F
authors: RP
authors: Dullaart
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000503:physiopathology; D005260:Female; D053442:High-Density Lipoproteins, Pre-beta / Q000096:biosynthesis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013960:Thyroid Function Tests; D013974:Thyroxine / Q000097:blood*
chemical_list: D053442:High-Density Lipoproteins, Pre-beta; D013974:Thyroxine
keywords: High density lipoproteins; Phospholipid transfer protein; Pre-β-HDL; Thyroid function; Type 2 diabetes mellitus