Estado nutricional de iodo materno durante gestação e lactação e sua relação com deficiência de iodo em recém-nascidos e lactentes no município de Diamantina MG

Abstract

Introduction: Iodine deficiency still represents an important problem of public health service, being one of main avoidable causes of mental retardation among children around the world. Objective: The objective was to study factors that are associated to the nutritional status of maternal iodine during gestation and lactation, as well as the relation between maternal iodine deficiency and this deficiency prevalence on newborns and infants in Diamantina MG. Methodology: : It was a prospective study of populations basis that was accomplished from the evaluation of pregnants and their babies during two moments: gestation and lactation During gestation, ioduria excretion of mothers and maternal thyroid function were analyzed by serum TSH rating and free T4. Post-partum, the analysis were on ioduria excretion of mothers, iodine on mothers milk, levels of new-born TSH and ioduria of infants. Ioduria was evaluated by spectrophotometric method being considered deficient the pregnants with ioduria < 150.0 µg/L, lactanting women and infants with ioduria < 100.0 µg/L. The new-born TSH was evaluated during the routine of the neonatal program for congenital hypothyroidism being considered deficient the newborns with TSH superior to 5mlU/L. Results: Prevalence of iodine deficient excretion found among pregnants and lactanting women was meaningful (73.8% and 71.8%), while the median of 94.6 µg/L (IIQ: 63.9 151.4 µg/L) and 60.1 µg/L (IIQ: 31.3 108.7 µg/L, respectively, showed a moderate deficiency for both groups. Risk factors associated to higher prevalence of iodine deficiency on the evaluated pregnants were: not working with a salary and use home-made seasoning. Using seasonings from industries, adding or substituting salt in the kitchen, came as a protection to deficient excretion of urinary iodine. It was not observed a significant relation between levels of TSH or free maternal T4 and iodine concentration on urine. Concentration of urinary iodine during gestational period performed as protection to ioduria deficient excretion among nursing-mothers, being that on how iodide salt was consumed. The iodine median observed in the milk was 176.95 µg/L (IIQ: 65.8 294.3 µg/L) and its distribution was related to social factors (mothers schooling and skin color) and biological factors (mothers ages and ioduria concentration on lactating). Proportion of new-born TSH was 0.5%, characterizing iodine sufficiency among newborns evaluated. Median of urinary iodine among infants were 172.9 µg/L (91.5 to 278.2 µg/L) showing also an adequate situation of iodine nutrition. Maternal ioduria during lactation (p < 0.001) and iodine content on mothers milk (p = 0.001) were positive and significantly associated to urinary iodine excretion among infants, even after adjustment of age, gender and weight at being born time. Conclusion: Although iodine deficiency still designs a problem of public health among pregnants and lactanting women, both investigated indicators, newborns and infants, showed an adequate situation of iodine nutrition. Maternal iodine deficiency in both stages seemed to be associated to social and biological factors and to how iodide salt is consumed. Ioduria excretation among infants is influenced by nutritional status of maternal iodine as mothers ioduria during lactation and content of iodine on mothers milk.