title: Low normal thyroid function as a determinant of increased large very low density lipoprotein particles.
abstract: OBJECTIVE
  Low-normal thyroid function may relate to increases in plasma cholesterol and triglycerides, but effects on lipoprotein subfractions are largely unknown. Associations of alterations in lipoprotein metabolism and functionality with low-normal thyroid function could be more pronounced in Type 2 diabetes mellitus (T2DM). We determined relationships of plasma lipids and lipoprotein subfractions with thyroid-stimulating hormone (TSH) and free thyroxine (free T4) in euthyroid subjects, and assessed whether such relationships are modified in the context of T2DM.
  
  
  METHODS
  TSH, free T4, (apo)lipoproteins and lipoprotein subfractions (nuclear magnetic resonance spectroscopy) were measured after an overnight fast in 61 T2DM subjects and 52 non-diabetic subjects.
  
  
  RESULTS
  TSH and free T4 were similar in T2DM and non-diabetic subjects. Plasma triglycerides, large very low density (VLDL) particles, VLDL size and small low density lipoprotein (LDL) particles were increased, whereas high density lipoprotein (HDL) cholesterol was decreased in T2DM subjects (p ≤ 0.05 for each). Age-, sex-, and diabetes status-adjusted multivariable linear regression analysis demonstrated that plasma triglycerides were associated positively with TSH (β=0.196, p=0.039). Large VLDL particles (β=-0.215, p=0.020) and VLDL size were inversely associated with free T4 (β=-0.285, p<0.001). These relationships were not significantly modified by diabetes status (interaction terms: p>0.10 for each). In all subjects combined, LDL and HDL subfraction characteristics were not significantly related to thyroid function status.
  
  
  CONCLUSIONS
  Low-normal thyroid function may confer increased plasma triglycerides, large VLDL particles and increased VLDL particle size. These relationships are not to a major extent modified in the context of T2DM.
authors: Department of Endocrinology, University of Groningen and University Medical Center Groningen, Groningen, The Netherlands.
authors: Lynnda
authors: L
authors: van Tienhoven-Wind
authors: Department of Endocrinology, University of Groningen and University Medical Center Groningen, Groningen, The Netherlands. Electronic address: r.p.f.dullaart@umcg.nl.
authors: Robin P F
authors: RP
authors: Dullaart
mesh_terms: D000368:Aged; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008079:Lipoproteins, VLDL / Q000097:blood*; D008297:Male; D008875:Middle Aged; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000502:physiology*; D013972:Thyrotropin / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
chemical_list: D008079:Lipoproteins, VLDL; D014284:Triiodothyronine; D013972:Thyrotropin
keywords: Nuclear magnetic resonance spectroscopy; Thyroid function; Triglycerides; Type 2 diabetes mellitus; Very low density lipoprotein subfractions