Mother-infant's iodine metabolism and thyroid function during lactation with different iodine intakes / 中华内分泌代谢杂志

ABSTRACT

Objective To study mother and infant's iodine metabolism and thyroid function during lactation with different iodine intakes. Methods Wistar rats were randomly assigned to four groups with severe iodine deficiency (SID), mild iodine deficiency (MiID), normal iodine (NI), and excessive iodine (ExI) intake respectively. All rats were fed on an iodine deficient food and drinking water with different quantities of potassium iodide for 3 months until mating. The urinary iodine, milk iodine, blood iodine, and thyroid hormones (TH) were detected in lactating mother and the offspring rats 14 days after birth. Thyroid weight of mother rats was determined. Thyroid morphology of mother and their offsprings was observed. Results ( 1) Iodine contents in urine, milk, and blood of lactating rats and the offsprings were increased with the increase of iodine supplied in diet. But the change in amplitude between groups was decreased in the other; urine iodine > milk iodine > blood iodine. (2) Serum TT4[ (16. 7±12. 0 vs 36.4±15. 0) nmol/L, P<0.05] was significantly decreased, but TSH [(5.73±2.90vs 1. 38±0.30)mIU/L, P<0.01]and TT3/TT4(6.6±2.7 vs 2. l±0.3,P<0.01) were increased in lactating rats of SID group compared with NI, so as TT4( 10.6±2. 3 vs 16.4±4. 7) nmol/L, P<0.05 ] of offspring rats in SID, but were not in MiID and ExI groups. (3 ) Histological studies showed that small follicular thyroid nodules with follicular hyperplasia occurred in both lactating rats and their offsprings in the SID group, mild swelling in MiID group and polymorphism changes appeared in mother rats of ExI group, but no significant difference appeared in offsprings compared with NI group. Conclusions Severe iodine deficiency will lead to hypothyroidism in mother and infant, but normal iodine nutrition and thyroid function in mother and offspring were maintained through the compensatory action of mother and child in mild iodine deficiency and iodine excess.