When do the normalization of thyroid hormone level happen?

A 5-year-old male child is admitted post valvular surgery to cardiac ICU.  A consultation is sent saying that there is a suspicion of secondary hypo-thyroidism. The results are as below  • T3–80 ng/dL (94–269 ng/dL)  • T4–3 μg/dL (7–15 μg/dL)  • TSH–0.02 μ IU/mL (0.5–5.0 μ IU/L)  What is the clinical diagnosis in this case?  What is the next step in evaluation of this patient?  What other parameters can help in the diagnosis?  The child was evaluated for other evidences of hypopituitarism as below The child is in the 5th centile which is expected as the child had untreated cyanotic congenital heart disease because of which the growth is stunted so probably growth hormone deficiency does not exist. The child has no evidence of micropenis so hypopituitarism was less of a possibility as it can be a marker of hypopituitarism. The child is maintaining blood pressure and is not requiring any ionotropic support which is an indirect evidence of normal cortisol levels. Thus, the clinical diagnosis in this child is kept as sick euthyroid syndrome as the other pituitary hormones are normal and there is no clinical evidence of hypopituitarism in this child. The levels of FT4 and FT3 are also done and FT4 is found to be in the normal range for age while FT3 is low. The other anterior pituitary hormones including random serum cortisol, FSH, LH and prolactin are measured in this child and the levels are found to be normal as per the clinical state of the patient. An IGF-1 level is done to screen for growth hormone deficiency and it is found to be in the normal range for age and sex matched controls. Different critical illness states leading to NTIS  • Sepsis and trauma  • Starvation  • Cardiac dysfunction  • Renal disease  • Hepatic disease  • Nonseptic shock  • Burns  • Respiratory failure  • Other disease states like systemic sclerosis

When do the normalization of thyroid hormone level happen?