Overview
Also known as non-thyroidal illness, sick euthyroid syndrome describes low free T3 (FT3), free T4 (FT4), and low/normal thyroid-stimulating hormone (TSH). It is generally seen in patients after critical illness, starvation, or intensive care. It is thought to occur due to changes in the hypothalamus-pituitary-thyroid axis.
Patients generally do not have symptoms and changes are reversible upon recovery. No treatment is generally needed.
