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Serum lipoprotein and apolipoprotein concentrations and tissue lipoprotein‐lipase activity in overt and subclinical hypothyroidism: the effect of substitution therapy
Author(s) -
LITHELL HANS,
BOBERG JONES,
HELLSING KRISTOFFER,
LJUNGHALL SVERKER,
LUNDQVIST GUDMAR,
VESSBY BENGT,
WIDE LEIF
Publication year - 1981
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1111/j.1365-2362.1981.tb01758.x
Subject(s) - medicine , endocrinology , triglyceride , apolipoprotein b , adipose tissue , lipoprotein lipase , lipoprotein , chemistry , hepatic lipase , high density lipoprotein , hormone , cholesterol
. Twenty‐one patients with increased, thyroid‐stimulating‐hormone (TSH) concentrations in the serum while fasting were studied before and after substitution with l‐thyroxine. Nine patients had TSH values < 40 mU/1 and an average serum‐thyroxine value of 64 nmol/1. Twelve patients with TSH‐values > 40 mU/1 had an average serum‐thyroxine value of 23 nmol/1. On treatment TSH and thyroxine normalized (reference limits < 8 mU/1 and 65–160 nmol/1 respectively) as did also the response to a load with thyroid‐releasing hormone (TRH). In the group with severe thyroid dysfunction (TSH > 40 mU/1) the lipoprotein‐lipase activities in both adipose and skeletal‐muscle tissue were subnormal before therapy and increased during substitution treatment. This was also reflected in a significant increase of the post‐heparin, lipoprotein‐lipase activity in the plasma and of the fractional removal rate of an i.v. injected fat emulsion. Ten out of twelve patients showed a decrease of the triglyceride concentration in whole serum, which reflected changes of the triglyceride concentrations in low‐density lipoproteins (LDL) and high‐density lipoproteins (HDL) more than changes in very‐low‐density lipoproteins, in which the triglyceride concentration was unchanged during treatment. In LDL, both the cholesterol and triglyceride concentrations were elevated before therapy and decreased by 22% and 32% of the pretreatment values, respectively, during treatment. Furthermore, the serum‐apolipoprotein‐B concentration decreased by 16%. The serum‐apolipoprotein‐A‐I concentration was subnormal before treatment and the lipid composition of the HDL particle was changed towards an enrichment of triglycerides. During treatment, the HDL‐triglyceride concentration decreased, whereas that of HDL cholesterol was unchanged. The fasting serum‐insulin concentration increased significantly during the treatment period. In the group with mild hypothyroidism (TSH < 40 mU/1), there were no significant changes similar to those found in severe hypothyroidism.