Low-density lipoprotein size in primary hypothyroidism - Effects of hormone replacement therapy

Background/Aim: Hypothyroidism is associated with abnormalities in lipid me tabolism but its effect on LDL size is not known. This study identified the LDL particle size (pattern 'A' or 'B') in a group of 50 postmenopausal wom en with primary hypothyroidism before and after 2 months of hormone replace ment therapy (HRT) with the aim of establishing whether hypothyroidism is a ssociated with an increased frequency of pattern B LDL compared with health y controls, and whether euthyroid recovery modified LDL size. Methods: Lipi d parameters (total cholesterol, triglycerides, HDL- and LDL-cholesterol, a po-protein Al and B and lipoprotein(a)) were determined in a blood sample f rom each patient and control. LDL size was determined by gradient gel elect rophoresis. Determinations were done before and after 2 months of HRT (75-1 50 mu g L-tiroxina/daily) in patients and once in controls. Results/Conclus ions: No significant difference emerged in pattern B LDL distribution: 16% in patients and 18% in controls (p = NS). After HRT no statistical variatio ns were observed in LDL size. HRT normalized all other lipid parameters exc ept lipoprotein(a). In conclusion, the increased risk of coronary heart dis ease assumed to be associated with hypothyroidism is not linked with the pr esence of pattern B LDL, bur rather with concomitant metabolic abnormalitie s. Copyright (C) 2000 S. Karger AG. Basel.