Effect of Delayed Elevation of Thyrotropin on Feeding Intolerance in Very Low Birth Weight Infants

Abstract

Purpose We investigated the effect of delayed elevation of thyrotropin (TSH) (deTSH) on gastrointestinal motility in very low birth weight infants (VLBWI). Methods This study retrospectively investigated 228 premature VLBWI aged ≥4 weeks with normal neonatal TSH screening test results and free serum thyroxine levels. Infants with serum TSH levels ranging from 5 to 10 μIU/mL were categorized as the deTSH group (n=76), when TSH was measured at 4 (n=53), 8 (n=20), or 12 (n=3) weeks of age. Serum TSH levels in the control group (n=152) were <5 μIU/mL. Multivariate logistic regression analysis was used to determine the risk factors for the development of deTSH. Covariance analysis was used to analyze the relationship between deTSH and gastrointestinal motility. Results The mean gestational age and birth weight were 29.11±2.25 weeks and 1,157.4±218.0 g, respectively. Risk factors affecting deTSH were dopamine administration (odds ratio [OR], 8.71; 95% confidence interval [CI], 1.80 to 42.05; P=0.007) and operation time (OR, 6.95; 95% CI, 1.43 to 33.75; P=0.016) when the cumulative operating time was ≥1 hour. The mean±standard deviation (SD) duration of a nil per os (NPO) status was significantly higher in the deTSH (99.57±134.99 hours) than in the control group (37.25±59.02 hours) (P from analysis of covariance [ANCOVA]=0.001). The mean±SD duration (33.84±22.34 days) of total parenteral nutrition (TPN) was considerably longer in the deTSH group than in the control group (27.68±13.08 days) (P from ANCOVA=0.003). Conclusion Clinicians must consider deTSH in VLBWI showing feeding intolerance with a prolonged NPO and TPN status.

Keywords

• infant, very low birth weight
• thyrotropin
• dopamine
• parenteral nutrition