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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
Author(s) -
Dedecjus Marek,
Masson David,
Gautier Thomas,
De Barros JeanPaul Pais,
Gambert Philippe,
Lewinski Andrzej,
Adamczewski Zbigniew,
Moulin Philippe,
Lagrost Laurent
Publication year - 2003
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1046/j.1365-2265.2003.01755.x
Subject(s) - cholesterylester transfer protein , medicine , endocrinology , lipoprotein , chemistry , high density lipoprotein , apolipoprotein b , cholesterol
Summary objectives 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 patients, design and measurements Sixty‐six thyroidectomized patients were withdrawn from L ‐thyroxine (L‐T 4 ) treatment for 5 weeks. Subsequently, L‐T 4 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‐T 4 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 HDL 2b and HDL 2a (HDL 2b : 13·6 ± 6·5% before vs. 8·5 ± 4·2% during L‐T 4 therapy, P < 0·05; HDL 2a , 33·0 ± 7·0% before vs. 29·3 ± 6·9% during L‐T 4 therapy, P < 0·05). Although serum CETP mass concentration correlated negatively with the HDL 2 to HDL 3 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.