Abstract:

Objective To investigate the relationship of selenium in whole blood and thyroid function in maintenance hemodialysis(MHD) patients and its clinical significance. Methods Selenium in whole blood, serum total triiodothyronine(TT3), total thyroxine(TT4), free-T3(FT 3) free-T4 ( FT4 ), sensitive thyroid stimulating hormone (s-TSH), parathyroid hormone(PTH), malondialdehyde(MDA) and nitric oxide(NO) concentrations and glutathione perodase(GSH-px) and supperoxide dismutase(SOD) activities were measured in 20 MHD patients, 20 non-dialysis uremic patients and 20 normal controls(NC). The relationship between above parameters and the change of selenium in whole blood was analyzed by multiple logistic regression analysis. Results ①The selenium concentration in whole blood of MHD patients was significantly lower than that in NC(P＜0.01), and lower than that in non-dialysis uremic patients without statistical sigbificance(P＜0.05); ②MHD patients had significantly lower serum TT3, TT4, FT3 and FT4 levels than those in NC(P＜0.01), but without significant difference of those between MHD patients and non-dialysis uremic patients; ③Serum PTH concentration in MHD patients was much higher than that of NC(P＜0.01), but that between MHD patients and non-dialysis uremic patients was not different; ④MHD patients had significant lower serum SOD and GSH-px activities than those in NC( P＜0.01)and their MDA levels was significantly higher(P＜0.01). SOD and GSH-px activities in MHD patients were much lower than those of non- dialysis uremic patients(P＜0.01) and MDA levels between MHD patients and non-dialysis uremic patients was not different; ⑤Multiple logistic regression analysis showed that concentration of selenium in whole blood in MHD patients was positively or related with serum TT3 ( r=0.429, P＜0.01) and FT3 (r =0.322, P＜0.05), SOD(r =0.498, P＜0.01) and GSH-px(r=0.390, P＜0.01) and negatively correlated with PTH (r =－0.491,P＜0.01) and MDA (r=－0.315, P＜ 0.05). Serum TT3 levels was negatively correlated significantly with MDA(r =－0.365, P＜0.01) and positively or related with SOD(r=0.359, P＜ 0.01) and GSH-px (r=0.296, P ＜0.05). Serum FT3 levels was negatively correlated with MDA(r=-0.302,P＜0.05) and positively related to GSH-px (r=0.306, P＜0.05). Serum FT4 concentration had negatively correlated with GSH-px(r =－0.327, P＜0.01). Conclusion Selenium deficiency may inhibit the course to transform T4 into T3 by reducing typeⅠiodothyronine 5′-deiodinase(ⅠD-Ⅰ) activity,incrasing serum PTH level,enhancing oxidative stress and weakening body’s antioxidative defence and then reduce the concentration of T3 in peripheral tissues.Therefore it is entirely possible that selenium deficiency will effect thyroid function in MHD patients.

Key words: Thyroid hormone, Parathyroid hormone, Lipid peroxides, Hemodialysis