Abstract
In order to evaluate influences of thyroid hormone on serum lipid and apoprotein metabolism, serum lipid, lipoprotein and apoprotein levels were studied in 15 hypothyroid and 18 hyperthyroid patients before and after therapy. Lipoproteins were isolated by serial ultracentrifugation. Apoproteins were determined by SRID method.
Total cholesterol (TC), intermediate density lipoprotein (IDL), low density lipoprotein (LDL) and high density lipoprotein (HDL) cholesterol (C) levels (mean±SD) were elevated in the untreaed hypothyroid patients compared to 26 normal subjects (261±66mg/dl versus 194±37mg/dl, 13±12mg/dl versus 8±4mg/dl, 158±67mg/dl versus 105±29mg/dl and 72±26mg/dl versus 59±16mg/dl, respectively).
Otherwise, TC and LDL-C levels were significantly lower in hyperthyroid patients as compared to the control group (132±23mg/dl versus 194±37mg/dl and 59±20mg/dl versus 105±29mg/dl, respectively). When hyperthyroid patients were restudied after restoration of the euthyroid state, HDL-C increased from 56±17mg/dl to 67±18mg/dl.
The LDL-C/HDL-C ratio was 2.8 in the hypothyroid patients, compared to 1.9 in the controls and 1.1 in the hyperthyroid patients. The very low density lipoprotein (VLDL-C/VLDL-triglyceride (TG) ratio were elevated in the hypothyroid patients. Apo B, apo C-II and apo E concentrations were increased in the hypothyroid patients compared to the controls (139±39mg/dl versus 103±23mg/dl, 5.5±2.3mg/dl versus 3.6±1.1mg/dl and 5.9±1.9mg/dl versus 4.2±0.8mg/dl, respectively). Apo A-I, apo A-II and apo B levels were decreased in untreated hyperthyroid patients compared to the euthyroid state (113±29mg/dl versus 151±36mg/dl, 22±5mg/dl versus 31±9mg/dl and 70±30mg/dl versus 103±25mg/dl, respectively).
On rendering the patients euthyroid, most of these changes in the lipid and apoprotein values were reversed.
