Significance of high levels of serum malonyl dialdehyde (MDA) and ceruloplasmin (CP) in hyper- and hypothyroidism.

The lipid peroxidation process is enhanced in both hyperoxygenated or underoxygenated tissues though its mechanism of production is different. Because in thyroid functional diseases there are severe disorders in tissue oxygenation we studied the lipid peroxidation process by using the serum level of malondialdehyde (MDA) as indicator. We also determined the serum ceruloplasmin (CP), an enzymatic protein belonging to the circulating system of antioxidative protection and also playing a role in the cell-mediated immunity. We also followed serum level of uric acid (UA). The determinations were performed on serum samples collected from three groups: 1, adult control subjects: 2. adult untreated hyperthyroid patients, and 3. adult hypothyroid thyroidectomized patients to whom replacement therapy was discontinued for at least 15 days. The mean MDA level was significantly higher in both hyperthyroid and hypothyroid patients by comparison to the control group. CP mean level was significantly lower than in controls. It was concluded that in post thyroidectomy hypothyroidism an enhancement of lipid peroxidation does exist and that its consequences are probably aggravated by the low serum CP level. The enhancement of the process occurs by other mechanisms than for hyperthyroid group. At hypothyroid patients there is an ADP excess which is degenerated to xanthine, the substrate of xanthine oxidase resulting in toxic anion superoxide and UA. In contrast with hyperthyroid group, in hypothyroid patients we observed significant higher values of UA in comparison to the controls. The excess of MDA found in hyperthyroid patients is statistically significant, but its consequences are probably less severe because the serum CP is higher than normal, a rather expected finding for an autoimmune disease.