title: Lipoprotein alterations, hepatic lipase activity, and insulin sensitivity in subclinical hypothyroidism: response to L-T(4) treatment.
abstract: Subclinical hypothyroidism (sH) has been associated with atherosclerotic cardiovascular disease even in the absence of hypercholesterolemia.
  
  
  OBJECTIVE
  Our study was designed to assess the hypothesis that other pro-atherogenic parameters, such as qualitative lipoprotein changes and insulin resistance, might be present in sH.
  
  
  METHODS
  Twenty-one sH women were compared to 11 female controls matched for body mass index, menopausal status, and age. Before and after 6 months of levothyroxine (L-T(4)) treatment, we determined total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides (TG), apoB levels, hepatic lipase (HL) activity in postheparin plasma samples, the chemical composition and copper-induced oxidation in isolated LDL and homeostasis model assessment (HOMA), quantitative insulin sensitivity check index, and insulinogenic index.
  
  
  RESULTS
  Lipid profiles were similar between the two groups. No differences in LDL oxidability or the insulin sensitivity assessment parameters were found. HL activity was significantly lower in the sH patients: median (range), 13.1 (2.5-26.7) vs. 18.7 (7.9-28.1) micromol free fatty acids/mL, p < 0.04. The LDL-cholesterol/LDL-TG ratio was decreased in sH: 3.9 (1.8-5.5) vs. 4.7 (3.5-6.8), p < 0.02. HL negatively correlated with thyroid-stimulating hormone (TSH) levels (r = - 0.504, p < 0.01) and positively with LDL-cholesterol/LDL-TG (r = 0.46, p < 0.02). Posttreatment results for all these parameters did not differ significantly compared to baseline.
  
  
  CONCLUSIONS
  Increased levels of TSH are associated to a decrease in HL activity, explaining our findings of an LDL particle rich in TG. This qualitative lipoprotein alteration suggests a pro-atherogenic pattern in sH. Treatment with L-T(4), however, did not correct the basal lipid derangement.
authors.affiliation: Division of Endocrinology and Metabolism, Hospital Francés de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Brenta
authors.forename: Gabriela
authors.initials: G
authors.lastname: Berg
authors.forename: Pablo
authors.initials: P
authors.lastname: Arias
authors.forename: Valeria
authors.initials: V
authors.lastname: Zago
authors.forename: Marta
authors.initials: M
authors.lastname: Schnitman
authors.forename: Maria Luz
authors.initials: ML
authors.lastname: Muzzio
authors.forename: Isaac
authors.initials: I
authors.lastname: Sinay
authors.forename: Laura
authors.initials: L
authors.lastname: Schreier
mesh_terms: D000328:Adult; D000368:Aged; D008078:Cholesterol, LDL / Q000097:blood; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000188:drug therapy* / Q000378:metabolism; D007333:Insulin Resistance; D008049:Lipase / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008875:Middle Aged; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000627:therapeutic use*; D014280:Triglycerides / Q000097:blood
chemical_list: D008078:Cholesterol, LDL; C504173:LIPC protein, human; D008077:Lipoproteins, LDL; D014280:Triglycerides; C099252:oxidized low density lipoprotein; D013972:Thyrotropin; D008049:Lipase; D013974:Thyroxine