Iodine nutrition status of exclusively breast-fed infants and their mothers in New Delhi, India.

Objective: To assess the iodine nutrition status of exclusively breast-fed infants and their mothers.

Hypothesis: In the presence of environmental and maternal iodine deficiency, an exclusively breast-fed baby is likely to receive a suboptimal iodine supply during the period of rapid brain growth.

Methods: Spot urinary iodine (UI) and serum TSH levels were measured in 175 healthy, exclusively breast-fed infants and their mothers. Iodine content of salt used by participants for domestic consumption was also analyzed.

Results: The median UI levels in mothers and infants was 124 microg/l and 162 microg/l, respectively. 34% of mothers and 21% of infants had UI levels <100 microg/l indicating iodine deficiency. Serum TSH was elevated in 29% of mothers and 2% of infants. No correlation was observed between individual mother-infant UI or serum TSH levels (r = -0.036, r = -0.1 for UI excretion and serum TSH, respectively). 96% of the salt samples tested had adequate iodine concentration, i.e. >15 ppm.

Conclusion: The present study demonstrated significant iodine deficiency in both mothers and infants despite consumption of adequately iodized salt. The iodine nutrition status of the infants was better compared to the mothers, indicating a preferential iodine supply to the infants over the mothers.