[Iodine deficiency and pregnancy].
Iodine availability for maternal thyroid during pregnancy results from a combination of specific factors (increased urinary iodine loss, fetal-placental unit competition) and is critically reduced by the nutritional deficiency. Hyperestrogenism is associated with increased circulating thyroxine-binding globulin (TBG) levels and a higher binding capacity for T4 and T3, because of a reduced clearance rate of the protein. Our study carried out in a moderately iodine deficiency area from North-Eastern Sicily in pregnant women showed a inadequate synthesis of T4 not proportional to the increased TBG levels. The progressive decrease T4/TBG molar ratio implies the reduction of serum FT4 and the consequently increase of serum TSH. At delivery, about 70% of women showed a critical and transient biochemical hypothyroidism. Mental impairment and neurosensorial and neuromuscular disorders were observed in children born from those women. Therefore, short-term iodine prophylaxis with iodized salt in pregnant women does not correct nor prevent maternal hypothyroxinemia. L-T4 treatment is thus often required.
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Istituto di Clinica Medica, Cattedra di Endocrinologia, Università degli Studi, Messina.
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D003409:Congenital Hypothyroidism / Q000209:etiology; D003677:Deficiency Diseases / Q000150:complications / Q000378:metabolism*; D005260:Female; D006801:Humans; D007455:Iodine / Q000172:deficiency*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000378:metabolism*; D016606:Thyroid Nodule / Q000209:etiology; D013974:Thyroxine / Q000378:metabolism; D013975:Thyroxine-Binding Proteins / Q000378:metabolism; D014284:Triiodothyronine / Q000378:metabolism
D013975:Thyroxine-Binding Proteins; D014284:Triiodothyronine; D007455:Iodine; D013974:Thyroxine