[Circulating levels of CoQ10 in hypo- and hyperthyroidism].

Coenzyme Q10 (CoQ10) plays an essential physiologic role in oxidative phosphorylation and its plasma and tissue concentration has been evaluated in various pathologic conditions, both endocrine and non endocrine; among the latter particularly in cardiac failure. Plasma CoQ10 determination has been reported in the literature an a useful diagnostic tool in differential diagnosis of thyroid diseases. In the present study we have evaluated CoQ10 circulating levels both in hypo- and hyperthyroidism. For this purpose plasma CoQ10, fT3-fT4 and TSH concentrations have been determined (HPLC, RIA and IRMA respectively) in a group of hypothyroid patients, hyperthyroid and control subjects. No patient was harbouring cardiovascular, metabolic or systemic disease. CoQ10 has resulted 0.97 +/- 0.46 mcg/ml in the hypothyroid group, 0.51 +/- 0.35 in hyperthyroid and 0.73 +/- 0.16 in control group, with a significative difference between first and second group only; more, the prevalence of high levels has appeared greater in hypo- towards hyperthyroid patients and that of low levels in the latter greater than in the former. Finally an inverse relation of CoQ10 with fT3 and tT3, but not with fT4 and tT4, has been shown. In conclusion, plasma CoQ10 levels have not given in this study a sharp distinction between euthyroidism on a side and hypo- and hyperthyroidism on the other, but necessity of longitudinal studies after therapy is outlined, both to know time of normalization of plasma concentrations and to verify the opportunity of exogenous administration of CoQ10 in hyperthyroid patients with risk factors for heart failure.