Endocrine Abstracts

Biological significance of microelements depends on concentration and interaction between them. Children are more sensitive to micronutrients imbalance. The aim was to estimate the microelement imbalance influence on the thyroid gland function and physical, mental and intellectual development of the children.

Growth and weight were estimated by CDC 2000, psychological status from birth by the skills and speech development, from 8 years by Luscher, Kos, Schulte, verbal, drawing, and correction tests, IQ Raven’s test; thyroid gland ultrasound; TSH, fT₄, fT₃, and TPO-Ab by IEA; urinary iodine by kinetic cerium-arsenical method; hair analysis for metals by ICP-mass spectrometry; methods of descriptive and nonparametric statistics.

Were examined 74 children aged 9 years living in environmentally disadvantaged region of the Tatarstan Republic (Nizhnekamsk). They were divided according to the cut-off point of lead concentration 5 mg/kg into two groups: main group, n=18 (≥5 mg/kg) and the comparison group, n=56, (<5 mg/kg). Control group consisted of apparently healthy children from Kazan (n=30).

Elevated lead correlated with a cadmium valid increasing (P<0.003). Elevated concentrations of lead and cadmium reliably correlated with urinary iodine decreasing (P<0.0001) and TSH increasing (P<0.02). Medians of thyroid hormones were: TSH, 3.82 and 2.05 mU/l (P<0.001), fT₄-16.2 and 14.8 pmol/ml, fT₃, 12.1 and 8.41 pg/ml (P<0.01) in the main and control groups respectively. 75% of the main group had a height below the 25th percentile, 73.3% of the control group had a height between 50 and 75th percentiles. The average IQ was 101.2 and 112.6 (P<0.02) in the main and control groups respectively. The main group has a significantly decreased logical, visual memory, attention and increased emotional lability, anxiety, and alexithymia.

The possible mechanisms of iodine and lead, cadmium, cobalt, nickel, copper, and zinc interactions may cause the thyroid gland dysfunction, and as a result, the delay of physical, mental and intellectual development of the children.