Article Text

  1. E F La Gamma1,
  2. A G vanWassenaer2,
  3. S Ares3,
  4. J H Kok2,
  5. J Quero3,
  6. S G Golombek1,
  7. G MorrealeDeEscobar4,
  8. T Hong5,
  9. H M Rabhar5,
  10. D Fisher6,
  11. N Paneth5
  1. 1The Regional Neonatal Center, Maria Fareri Children’s Hospital at Westchester Medical Center, New York Medical College, Valhalla, NY, USA
  2. 2Emma Children’s Hospital, Academic Medical Center, Amsterdam, Amsterdam, The Netherlands
  3. 3Neonatology Unit, University Hospital La Paz, Autonomous University of Madrid, Madrid, Spain
  4. 4Instituto de Investigaciones Biomedicas, Autonomous University of Madrid, Madrid, Spain
  5. 5Departments of Epidemiology and Pediatrics and Human Development, Michigan State University, East Lansing, MI, USA
  6. 6Quest Diagnostics Nichols Institute, San Juan Capistrano, CA, USA


Objective Hypothyroxinemia of prematurity occurs in ∼50% of preterm neonates and is associated with adverse neurodevelopmental outcomes. TH supplementation may improve outcome if the optimal dosing regimen were known.

Aim To determine a dosing protocol that could raise FT4 levels with the least TSH suppression.

Methods Neonates between 24–28 wks gestation were enrolled within 24 h of birth (Amsterdam, Madrid, NY) resulting in 168 subjects randomized to one of 6 treatment arms: placebo (D5W), potassium iodide (30 μg/kg/d) or continuous or bolus daily infusions of either 4 or 8 μg/kg/d of T4 for 42 ds+1 μg/kg/d T3×14 d in T4 Rx groups. FT4 (equilibrium dialysis), TT4, TSH, T3, (RIA) & TBG were measured on days 0, 3, 7, 14, 28, 42, & 56.

Results No significant differences were found across the groups for maternal or neonatal variables at enrollment. TT4 was elevated (p<0.03) and TSH was suppressed (<0.4 mU/L) in the first 14 days for supplemented groups compared to placebo/iodine. TT4 remained elevated >90 nM/L (7 μg/dl; p<0.01) in the treatment arms with the least suppression of TSH seen with 4 μg/kg/d T4 continuous infusion. Providing iodine supplements alone elevated FT4 (p<0.05) compared to placebo. No differences were seen in mortality. All subjects recovered to normal range by 2 weeks off study drug.

Conclusions Elevation of TT4 >50 nM/L with the least suppression of TSH, was achieved in neonates using a continuous supplement of 4 μg/kg/d for 42 d.

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