Introduction: Cobalt is a relatively rare magnetic element with properties similar to iron and nickel. Cobalt is an essential element necessary for the formation of vitamin B12; however, excessive administration of this trace element produces goiter and reduced thyroid activity. This study was done to compare the prevalence of cobalt excess (as a cause of goiter) between goiterous and non goiterous children and to assay the relationship between serum cobalt and thyroid hormones too.
Methods: This cross sectional study was carried out on 5380 randomly selected children aged 811 years. Anthropometric measurements and thyroid exam were done on all of them. Serum concentration of T4, T3, thyroid stimulating hormone (TSH), serum cobalt and urine iodine were analysed from a subsample of 169 goiterous children who were selected randomly. All above data were collected in an age and sex matched control group too.
Results: The serum cobalt level was significantly lower in case group (4.3±2.9 μg/l in case versus 6.3±2.7 μg/l in control group (P<0.0001)).The urine iodine level was significantly lower in case group. (19.8±10.9 μg/l in case versus 25.8±10.9 μg/l in control group (P<0.0001)).There was 12(7.1%) cases of cobalt deficiency and no one has cobalt excess. There was not a significant difference between Cobalt deficiency and goiter (P=0.07), but there was a significant difference between iodine deficiency and goiter (P=0.01). The total goiter rate was 34.8%(GII) and 100% of cobalt deficient children were goiterous. There was not a significant correlation between cobalt concentration and height, weight, BMI, T4, TSH and urine iodine, but there was a weak correlation with T3 (P=0.04, r=0.1).
Discussion: This study shows that goiterous children had lower serum cobalt concentration. In most of previous studies, cobalt excess was known as a cause of goiter. Further studies for detecting the effect of cobalt replacement on goiter size may be needed to establish the cause and relationship between cobalt deficiency and goiter.
Conclusion: Serum concentration of cobalt and urine iodine was lower in goiterous children and it may be a cause of goiter in our region (KermanIran).
03 - 07 May 2008
European Society of Endocrinology