 The classical phenotype of this condition is often seen in starvation, critical illness, or patients in the intensive care unit.Similar endocrine phenotypes are observed in fetal life and in hibernating mammals.The most common hormone pattern in NTIS (non-thyroidal illness syndrome) is low total and free T3, elevated rT3, and normal T4 and TSH levels, although T4 and TSH suppression may occur in more severe or chronic illness.