title: Low cholesteryl ester transfer protein (CETP) concentration but normal CETP activity in serum from patients with short-term hypothyroidism Lack of relationship to lipoprotein abnormalities.
abstract: OBJECTIVE
  Hypothyroidism is associated with a number of abnormalities in lipoprotein metabolism. Although alterations in neutral lipid exchanges among plasma lipoproteins might be one characteristic feature of hypothyroidism, a few human studies of cholesteryl ester transfer protein (CETP) activity have led to heterogeneous and fragmentary observations. The aim of the present study was to analyse the influence of short-term hypothyroidism on CETP activity, as well as on the structure and composition of lipoproteins. PATIENTS, DESIGN AND MEASUREMENTS: Sixty-six thyroidectomized patients were withdrawn from L-thyroxine (L-T4) treatment for 5 weeks. Subsequently, L-T4 therapy was reinstated for 2 months and patients were compared to 61 matched normolipidaemic controls. Serum CETP activity and mass concentration, serum lipids, apolipoproteins and lipoprotein size distribution were determined in the three groups.
  
  
  RESULTS
  Serum CETP mass concentration was significantly decreased in short-term hypothyroid patients, as compared to control subjects (3.22 +/- 0.98 vs. 3.79 +/- 1.2 mg/l, respectively; P < 0.001), and the values were normalized during L-T4 therapy. The ability of endogenous serum lipoproteins to interact with CETP was normal in short-term hypothyroid patients. Concordant observations were made regardless of whether neutral lipid transfers were measured from high-density lipoproteins (HDL) toward apo B-containing lipoproteins or from liposomes toward HDL. The size distribution of HDL was significantly different in short-term hypothyroid patients, compared to either the control or treated subgroups, with significant higher proportions of large-sized HDL2b and HDL2a (HDL2b: 13.6 +/- 6.5% before vs. 8.5 +/- 4.2% during L-T4 therapy, P < 0.05; HDL2a, 33.0 +/- 7.0% before vs. 29.3 +/- 6.9% during L-T4 therapy, P < 0.05). Although serum CETP mass concentration correlated negatively with the HDL2 to HDL3 ratio in control subjects (r = -0.588; P < 0.0001), no significant correlations were observed in hypothyroid patients, regardless of whether they were treated or not. Similarly, whereas the previously recognized positive correlation of CETP mass concentration with serum LDL cholesterol levels was found in control subjects (r = 0.264; P < 0.05), no significant correlations appeared in treated and untreated patients.
  
  
  CONCLUSIONS
  Short-term hypothyroidism may constitute an unique situation in which concomitant alterations in serum cholesteryl ester transfer protein concentration and lipoprotein parameters are disconnected.
authors.affiliation: Department of Thyroidology, Institute of Endocrinology, Medical University of Lódz, Lódz, Poland.
authors.forename: Marek
authors.initials: M
authors.lastname: Dedecjus
authors.forename: David
authors.initials: D
authors.lastname: Masson
authors.forename: Thomas
authors.initials: T
authors.lastname: Gautier
authors.forename: Jean-Paul Pais
authors.initials: JP
authors.lastname: de Barros
authors.forename: Philippe
authors.initials: P
authors.lastname: Gambert
authors.forename: Andrzej
authors.initials: A
authors.lastname: Lewinski
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Adamczewski
authors.forename: Philippe
authors.initials: P
authors.lastname: Moulin
authors.forename: Laurent
authors.initials: L
authors.lastname: Lagrost
mesh_terms: D001053:Apolipoproteins / Q000097:blood; D002352:Carrier Proteins / Q000097:blood*; D053480:Cholesterol Ester Transfer Proteins; D008078:Cholesterol, LDL / Q000097:blood; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006023:Glycoproteins; D006801:Humans; D007037:Hypothyroidism / Q000188:drug therapy / Q000378:metabolism*; D008074:Lipoproteins / Q000097:blood*; D008075:Lipoproteins, HDL; D008081:Liposomes / Q000097:blood; D013974:Thyroxine / Q000627:therapeutic use
chemical_list: D001053:Apolipoproteins; C506642:CETP protein, human; D002352:Carrier Proteins; D053480:Cholesterol Ester Transfer Proteins; D008078:Cholesterol, LDL; D006023:Glycoproteins; D008074:Lipoproteins; D008075:Lipoproteins, HDL; D008081:Liposomes; D013974:Thyroxine