determining mean level of thyroid hormones in 5th day, 2nd and 4th weeks in premature infants referred to nicus of aliasghar and akbarabady children hospitals

background and objective: thyroid function problems are often present with prematurity disorders. thyroid hormones regulate growth and distinguish body organs; especially they affect central nervous system and metabolism of carbohydrates, lipids, and vitamins. thus, these hormones should be evaluated. the present study aims to determine the mean level of thyroid hormones among premature infants referred to nicus of aliasghar and akbarabadi hospitals in 5th day, 2nd and 4th weeks. methods: in this cross-sectional study 140 infants who referred to aliasghar and akbarabadi hospitals nicu since may 2012 were examined after obtaining written consent from their proxies. at the 5th day 1cc blood sample was taken; and the procedure was repeated at the 2nd and 4th weeks. tsh and t4 were measured and the mean was calculated for the 3 stages. findings: a total of 140 patients (80 boys) were evaluated. gestational mean age was 31.91 weeks. at the 5th day the means of tsh and t4 were 4.16 and 8.71, at the 2nd week 4.47 and 8.12, and for the 4th week 4.08 and 8.76, respectively. conclusion: in current study tsh level at the 5th day was 4.16±3.3 and t3 serum level 8.71±3.4. tsh in 2nd week measuring was 4.47±2.5 and t4 was 5.12±2.9. at the 4th week the tsh level was 4.08±1.9 and t4 was 8.76±2.8. tsh level was independent from gestational age, but t4 serum level had direct association with gestational age. there was no relationship between thyroid hormones’ level with birth weight, thyroid disorders history in infants’ family, and consuming thyroid medications during pregnancy.