Endocrine Abstracts

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 8–11 years. Anthropometric measurements and thyroid exam were done on all of them. Serum concentration of T_4, 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%(G_II) 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 (Kerman–Iran).