Prevalence of thyroid dysfunction in neonates receiving parenteral nutrition in the intensive care unit

Objective: The use of parenteral nutrition (PN) formulations that do not contain iodine can contribute to the deficiency of this mineral, potentially leading to hypothyroidism and, ultimately, neurocognitive impairments. This study aimed to evaluate TSH alterations in newborns receiving PN.

Methods: Retrospective study of neonatal intensive care unit patients receiving PN for > 15 days. Nutritional, anthropometric, and biochemical variables (TSH, T4, CRP) were analyzed. Hypothyroidism was defined by TSH > 10 mU/L.

Results: Two hundred newborns were evaluated [156 (78%) preterm, 31±5 weeks of gestational age, 112 (56%) with very or extremely low birth weight]. The median (IQR) hospital stay was 68 (42-110) days, PN duration was 31 (21-47) days, and 188 (94%) patients also received enteral nutrition. Overall, 143 (71.5%) newborns underwent at least one TSH measurement. The prevalence of hypothyroidism was 10.5%. The Median PN duration in this group was 51 (34-109) days. Among those with hypothyroidism, 10 received Lugol's solution and six levothyroxine. Thirteen patients received prophylactic Lugol's solution with a median PN duration of 63 (48-197) days. TSH levels correlated positively with PN duration (r = 0.19, p = .02).

Conclusions: The present data suggest that changes in TSH and T4 levels are present in neonates receiving PN for > 15 days, suggesting this population may be at risk for developing hypothyroidism. Therefore, the authors suggest that TSH and T4 measurements should be included as routine in neonatal patients receiving PN for > 15 days if PN formulations are not supplemented with iodine, and that iodine supplementation be provided as necessary.