Format

Send to

Choose Destination
J Clin Endocrinol Metab. 2009 Nov;94(11):4444-7. doi: 10.1210/jc.2009-0632. Epub 2009 Oct 6.

Subclinical hypothyroidism in Korean preterm infants associated with high levels of iodine in breast milk.

Author information

1
Department of Pediatrics, Seoul National University Children's Hospital, Chongno-gu, Seoul 110-744, Republic of Korea.

Abstract

CONTEXT:

The dietary iodine intake of lactating women has been reported to be high in Korea.

OBJECTIVES:

The aim of this study was to assess iodine balance and to determine its relationship with thyroid function in preterm infants.

DESIGN:

Thyroid functions of preterm infants born at 34 wk gestation or less were evaluated in the first (n = 31) and third (n = 19) weeks. Mothers' breast milk (BM) and random urine samples of infants were taken on the same days for thyroid function tests.

RESULTS:

Iodine concentrations in BM were very high (198-8484 microg/liter), and one third of the infants had an iodine intake of more than 100 microg/kg per day at the third week after birth (excessive iodine intake group). At that time, the levels of TSH were positively correlated with urinary iodine (r = 0.622; P = 0.004). The frequencies of subclinical hypothyroidism were high in the excessive iodine intake group at the third and sixth weeks. The estimated daily iodine intake at the third week (51.2 +/- 45.5 vs. 149.0 +/- 103.8 microg/kg per day; P = 0.033), urinary iodine at the third week (913.2 +/- 1179.7 vs. 1651.3 +/- 1135.2 microg/liter; P = 0.051), and estimated daily iodine intake at the sixth week (32.8 +/- 35.5 vs. 92.1 +/- 51.2 microg/kg per day; P = 0.032) were significantly higher in infants with subclinical hypothyroidism than in controls.

CONCLUSIONS:

Excessive iodine intake from BM contributed to subclinical hypothyroidism in these preterm Korean infants.

PMID:
19808851
DOI:
10.1210/jc.2009-0632
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Silverchair Information Systems
Loading ...
Support Center