Effect of accepting a very low macronutrient intake, by omitting parenteral nutrition (PN) until beyond the first week in ICU (Late-PN), as compared with early provision of full feeding with PN (early-PN) on NTIS. Bars (mean – SE) represent the changes (referred to as Δ) from the admission values to day 3 in the adult or pediatric ICU (or to the last day for patients with shorter ICU stay) in serum TSH, T4, T3, rT3, and the T3/rT3 ratio. The open and filled bars represent the patients randomized to the early-PN and late-PN groups, respectively. [Reproduced with permission from Jacobs A, Derese I, Vander Perre S, van Puffelen E, Verstraete S, Pauwels L, Verbruggen S, Wouters P, Langouche L, Garcia Guerra G et al: Non-Thyroidal Illness Syndrome in Critically Ill Children: Prognostic Value and Impact of Nutritional Management. Thyroid 2019, 29(4):480-492; and Langouche L, Vander Perre S, Marques M, Boelen A, Wouters PJ, Casaer MP, Van den Berghe G: Impact of early nutrient restriction during critical illness on the nonthyroidal illness syndrome and its relation with outcome: a randomized, controlled clinical study. J Clin Endocrinol Metab. 2013;98(3):1006-1013.]