[Lipid changes as a possible risk factor in preclinical hypothyroidism. Preliminary report].

In a prospective study the lipids have been investigated in patients with preclinical hypothyroidism (normal values for thyroxine and free thyroxine index but exaggerated response to oral TRH and normal or elevated basal TSH). This group was compared with euthyroid normal subjects and patients with overt hypothyroidism. Cholesterol and triglycerides were normal in patients with preclinical hypothyroidism, in contrast to the increased levels in overt hypothyroidism. HDL cholesterol showed no difference in either group. Lipid electrophoresis on agarose with densitometric analysis revealed elevation of low density lipoproteins (LDL) and diminution of high density lipoproteins (HDL) in both groups of hypothyroid patients. The changes in LDL and HDL are both known coronary risk factors and could explain the reported prevalence of coronary disease in the early stages of thyroid failure. These preliminary findings need further confirmation.