enhanced inflammation is well - established in patients with chronic kidney disease ( ckd ) . several factors have been implicated in such inflammation in patients with ckd including uremic state , elevated serum inflammatory markers , oxidative stress , etc . ( 1 - 3 ) . systemic inflammation has important implications in renal failure and can lead to potentially severe conditions such as premature atherosclerosis . premature atherosclerosis is one of the main causes of death in hemodialysis patients ( 4 , 5 ) . some studies suggested that hemodialysis itself increases the production of free radicals ( 6 - 8 ) . in addition to inflammation , malnutrition has been considered as an important determinant factor in clinical outcome of patients with ckd ( 9 , 10 ) . among various nutritional elements in fact , there is extensive evidence that selenium level is depleted in patients with ckd , especially those under hemodialysis ( 4 , 5 , 12 ) . this nutrient is an essential part of enzymes of the body 's cells against free radicals by participating in the structure of glutathione peroxidase . free radicals are formed during natural oxygen metabolism process of body and have widespread destructive effects on body . one of the essential functions of selenium is preventing heart disease and elevated blood pressure ( 13 , 14 ) . in fact , the highest concentration of selenium inside the human body ( per gram tissue ) is found in the thyroid ( 15 ) . for long time this is mainly due to special selenoproteins inside the thyroid gland and activity of thyroid enzyme deiodinase , which requires selenium for its proper function ( 16 ) . abnormal changes reported include reduction in serum level of total and free t3 and t4 , increase in rt3 and tsh reduction ( 17 ) . in fact , hypothyroidism has been documented to occur in a higher rate in patients with ckd than general population ( 18 ) . considering the abnormal changes in tfts in patients with ckd , some authors advised mathematical calculations to correct tfts measurements so that a subnormal free t4 in a non - thyroidal disease would not cause confusion in diagnosing hypothyroidism ( 19 ) . since micronutrients are important components in metabolism pathways of proteins and enzymes and have many metabolic functions , any changes in their serum level can have profound impact on other important and critical parts of body . in view of the fact that selenium may influence inflammation and thyroid function , we decided to evaluate the role of selenium supplementation regarding any possible changes in inflammatory markers and tfts in patients with ckd undergoing hemodialysis . in this double - blinded clinical trial , 64 consecutive patients presented to out tertiary care center to undergo hemodialysis and six months had passed from hemodialysis initiation were included . exclusion criteria were acute viral infections in past three months , previous or current diseases of thyroid , taking steroidal and non - steroidal anti - inflammatory drugs , taking vitamins e and c and zinc during two past months prior to the study . before hemodialysis selenium measurement was performed via atomic absorption analysis using vapor generation accessory ( vga ) . patients with low levels of selenium were randomly divided ( using random number table ) into experimental ( 32 cases ) and control ( 32 cases ) groups . experimental group received selenium capsules ( 200 g / day ) for three months , while control group received placebo capsules for the same period .   for laboratory markers , 3 ml of venous blood this was performed twice first at the start of study and again after three months . the following markers were measured ; esr ( erythrocyte sedimentation rate ) , ferritin , quantitative c - reactive protein ( crp ) and thyroid function tests ( thyroid - stimulating hormone ( tsh ) , t3 resin uptake ( t3ru ) and free t4 ) . after completion of hemodialysis , weight was measured with light clothing using a weight scale with precision of 1 kg . height was also measured without shoes by a meter installed on the wall with precision of 1 cm . mean and standard deviation (  sd ) were used . to compare the data between experimental and control groups , independent t - test , paired t - test , wilcoxon after normal distribution of dependent variables and ascertaining proportional odds , ordinal regression was used , otherwise logistic regression was applied . the study protocol was confirmed by the ethics committee of research of kermanshah university of medical sciences , kermanshah , iran . written informed consent was obtained from patients . both selenium and placebo were delivered to patients free of charge . in case of detecting any abnormality in laboratory tests , mean (  sd ) age of experimental and control groups were 57.34 (  13.23 ) and 59.53 (  14.68 ) years , respectively ( p = 0.53 ) . there were 15 males ( 46.9% ) in experimental group and 17 females ( 53.1% ) in the control group . mean (  sd ) body mass index ( bmi ) values in experimental and control groups were 23.78 (  4.83 ) and 24.46 (  3.68 ) kg / m , respectively ( p = 0.54 ) . mean (  sd ) serum selenium levels before the intervention in experimental and control groups were 32.81 (  10.5 ) and 39.09 (  13.18 ) g / dl , respectively ( p = 0.049 ) . ancova showed that by controlling selenium effect before the intervention between the two groups , selenium change after the intervention was significant ( p < 0.001 ) . mean (  sd ) selenium levels after the intervention in experimental and control groups were 182.16 (  42.4 ) and 51.16 (  36.37 ) g / dl , respectively . table 1 presents the comparison between acute phase reactants measured at baseline and after three months . as seen , selenium supplementation did not have any significant effect on acute phase reactants . in table 2 , mean  sd values of thyroid function tests are presented at baseline and after intervention . abbreviations : crp : c - reactive protein , esr : erythrocyte sedimentation rate . we studied the effects of selenium supplementation in hemodialysis patients who had low serum levels of selenium . according to the obtained results , although serum selenium level increased significantly after supplementation and was higher after three months in experimental group compared to control group , selenium supplementation did not have any significant effect on acute phase reactants or tfts . at baseline , after three months , we observed increase in crp level in the both groups , but change in crp level in experimental group was less prominent than that of control group , though the difference was insignificant . ( 11 ) studied 80 hemodialysis patients in a randomized double - blind trial and followed them for three months to determine the effects of selenium supplementation on inflammatory markers . they reported no significant differences between selenium and placebo groups regarding changes in serum levels of lipoproteins , high - sensitivity crp , homocysteine , ferritin and transferrin . in their study , mean ferritin level in selenium group was 819.4 ng / ml with an interquartile range of 439.95 to 1180 , which changed by a mean of 23 ng / ml ( 95% ci = -26.67 to 168.58 ) and was not statistically different from the placebo group . mean hs - crp in selenium group was 4.5 with an interquartile range of 1.72 to 19.97 . after supplementation , hs - crp showed a mean decrease by 0.85 g / ml , which did not show significant difference to the control group . the only inflammatory marker decreased significantly in that study in selenium group was il-6 . in support of the concept of beneficial effects of selenium on oxidative stress and inflammation , previous reports recommended selenium supplementation in hemodialysis patients ( 20 , 21 ) . in another trial ( 22 ) , 45 mild , moderate and severe ckd patients of at least six - month duration were studied to find out the effect of selenium supplementation on red blood cell glutathione peroxidase ( gsh - pxs ) enzyme activity . the authors reported that this intervention was effective in increasing mean gsh - pxs level as well as plasma selenium level significantly regardless of ckd severity . we did not find any study about the effect of selenium supplementation on thyroid function in patients with ckd . there is only one study performed on patients with acute renal failure ( 23 ) . in the mentioned study , the role of kidney disease and its effect on tfts is supported further by reports which observed improvement in thyroid hormones and morphology after kidney transplantation ( 17 ) . we recommend to perform future studies with larger sample sizes to address controversy in the literature . in addition , the study period was relatively short . therefore , we recommend to perform future studies in longer periods on more patients . besides , various factors could affect acute phase reactants like infections , which were not able to monitor in this study . it is recommended to control confounding variables , which can adversely affect acute phase reactants such as crp and esr to yield better assessment of selenium effect on these inflammatory markers . the effect of selenium on inflammatory markers and tfts in hemodialysis patients is controversial . according to our findings , selenium supplementation via oral route for
background : selenium deficiency is a common problem in patients with chronic kidney disease ( ckd ) . 
 this micronutrient has anti - inflammatory and anti - oxidant effects . 
 selenium is also found in high concentrations in the thyroid gland.objectives:to determine the effect of selenium supplementation on thyroid function tests and acute phase reactants in hemodialysis patients.patients and methods : in this double - blinded randomized clinical in 3 months , 64 hemodialysis patients with selenium deficiency were divided into experimental ( received selenium supplementation ; 32 cases ) or control group ( received placebo ; 32 cases ) . 
 erythrocyte sedimentation rate ( esr ) , ferritin , quantitative c - reactive protein ( crp ) and thyroid function tests ( tfts ) including thyroid stimulating hormone ( tsh ) , t3 resin uptake ( t3ru ) , and free t4 were measured before and after the intervention and compared between experimental and control groups.results:at baseline , no significant difference was found between experimental and control groups regarding crp , esr and ferritin serum levels . likewise , 
 after intervention , no significant difference was found between experimental and control groups for crp ( 14.77  17.93 vs. 18.29  21.56 mg 
 / l ) , esr ( 32.90  32.62 vs. 33.91  31.15 mm / h ) and ferritin ( 528.6  423.07 vs. 519.52  345.59 ng / ml ) . at baseline 
 , no significant difference was found between experimental and control groups regarding tfts . 
 likewise , after intervention , no significant difference was found between experimental and control groups for tsh ( 3.7  2.22 vs. 2.84  1.88 u / ml ) , free t4 ( 7.19  1.98 vs. 7.02  1.87 g / dl ) and t3ru ( 30.04  2.28% vs. 29.2  1.98%).conclusions : oral selenium supplementation for three months did not have any significant effect on thyroid function tests or acute phase reactants .