Influence of Mild Iodine Deficiency and Latent Iron Deficiency on the Type of Reaction of Cardiovascular System in Physical Activity

The study involved 133 practically healthy (group of health I and II) children (68 boys and 65 girls), who were divided according to the age into two groups: Ist (n=68) – children aged from 6 to 11 years, IInd (n=65) – children from 12 to 18 years. In each age group all the children were divided into four subgroups: 1st – boys and girls with appropriate iodine and iron supply (control group), 2nd – children with limited iodine supply without iron deficiency, 3rd – with proper iodine supply and latent iron deficiency, 4th – with mild iodine deficiency and latent iron deficiency. In order to study thyroid gland function in blood serum samples, the contents of thyroid hormones were determined: free T3 (fT3) and T4 (fT4), thyroid stimulating hormone adenohypophysis (TSH). To determine the rate of iodine supply the index of urinary iodine excretion in urine single portions according to Sandell-Kolthoff reaction the median urinary iodine (Me) was found. Results of morphometry of the thyroid gland were evaluated according to the standards of thyroid volume (97 percentile) considering the sex and body surface area. To evaluate iron metabolism in children the level of hemoglobin (Hb) in capillary blood, serum iron (SI) level, common-binding capacity of serum (CBCS) with the help of ELISA test (test kit “Cormay”, Poland) were measured. Condition of iron stores was characterized by the level of serum ferritin (SF) level. Type of the reactions of cardiovascular system to the dosed physical activity was assessed using sample of Martine-Kushelevsky and counting the quality reaction index (QRI). To analyze the parameters of thyroid status in pupils with mild iodine deficiency (2nd and 4th subgroups), the reduction of fT3contents (at 18.5-19.9%, p<0.05) and fT4 (at 14.9- 20.8%, p<0.05) regardless of age and gender is determined. Also in these subgroups the increase of TSH in blood serum of boys at 2.5-2.6 times (p<0.05), in girls – at 2.8-3.4 times (p<0.05) is observed. These changes were associated with a decrease of the SI (at 44.9-53.6%, p<0.05), ferritin (at 43.5-69.0%, p<0.05) and were accompanied by the growth of CBCS (at 70.9-73.6%, p<0.05) as for the control. Iodine the reaction by QRI was the next one: it was good in 25% of boys and 22.2% of girls; satisfactory – in 50% of boys and 66.7% of girls; irrational – in 25% of boys and 11.1% of girls. Reaction to physical exercise in all children of this group is according to normotonic type; the recovery period does not exceed 3 minutes. In pupils with latent iron deficiency reaction by QRI was good in 37.5% of children and satisfactory in 62.5% of patients, the response to physical activity in all children is normotonic and recovery period does not exceed 3 minutes. On the basis of the combined trace element imbalance the reaction is good, normotonic in 11.1% of boys and 25% of girls; satisfactory in 55.6% of boys and 50% of girls; irrational – in 33.3% of boys and 25% of girls, including 66.7% of boys and 50% of girls whose reaction is by hypotonic type, and the recovery period was an average 5.3 minutes. The same tendency is in the IInd age group (pupils aged 12-18). At the same time in the 4th subgroup only 25% of children have good, normotonic reaction; 50% of boys and 37.5% of girls – satisfactory, normotonic reaction; 25% of boys and 37.5% of girls – poor reaction, of them in 12.5% of girls – it was hypertonic type of reaction with the recovery period of 4.5 minutes. On the basis of the trace element imbalance the thyroid homeostasis is impaired in pupils; it is accompanied by exhaustion of reserve-adaptive capacities.