title: Thyroid Function Test in Pre-term Neonates During the First Five Weeks of Life.
abstract: BACKGROUND
  Congenital hypothyroidism (CHT) is one of the most common congenital endocrinal disorders. The prevalence of CHT is estimated about 1 in 3,000 newborns. The prevalence, etiology and associated disorders of abnormal thyroid screening tests are reported in different ranges. In this study, we assessed the pre-term newborns for CHT and associated factors that influence thyroid function.
  
  
  METHODS
  One hundred newborns with the gestational age fewer than 35 weeks were investigated. Baseline serum thyroid stimulating hormone (TSH) and free thyroxin (FT4) levels were measured during the first 5 days of life and were repeated during the first 5 weeks. We analyzed the effects of demographic factors and the presence of respiratory distress syndrome on the alteration of thyroid function tests during the first 5 weeks of life.
  
  
  RESULTS
  The mean gestational age (GA) at delivery was 32.35í1.97 (range 28 to 35) weeks. CHT was observed in 13(13%) preterm infants. GA was the only factor which affect the FT4 changes over the two weeks follow-up (P < 0.001, b: -2.783, Power: 70.2%) although the differences between baseline and follow-up amount of TSH were not significantly influenced by GA (P = 0.062, power: 46%). However, the adjusted TSH and FT4 serum level changes during follow-up were significantly different between two groups (between CHT and normal, P = 0.006, 0.000, respectively).
  
  
  CONCLUSIONS
  It seems that thyroid function tests should be repeated in preterm infants, especially for patients with lower gestational age, to confirm the diagnosis of CHT. Also, CHT should be considered among the newborns that are affected by RDS.
authors.affiliation: Department of Pediatrics, Faculty of Medicine, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Torkaman
authors.affiliation: Department of Pediatrics, Faculty of Medicine, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Fariba
authors.initials: F
authors.lastname: Ghasemi
authors.affiliation: New Hearing Technologies Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Susan
authors.initials: S
authors.lastname: Amirsalari
authors.affiliation: Student Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Abyazi
authors.affiliation: Health Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Shahla
authors.initials: S
authors.lastname: Afsharpaiman
authors.affiliation: Department of Pediatrics, Faculty of Medicine, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Zohreh
authors.initials: Z
authors.lastname: Kavehmanesh
authors.affiliation: Department of Pediatrics, Faculty of Medicine, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Beiraghdar
authors.affiliation: Chemical Injuries Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran ; Atherosclerosis and Coronary Artery Research Centre, Birjand University of Medical Sciences, Birjand, Iran.
authors.forename: Amin
authors.initials: A
authors.lastname: Saburi
keywords: Congenital hypothyroidism; pre-term neonate; respiratory distress syndrome; thyroid screening tests