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.