[Diagnosis and treatment of intra-abdominal infection complicated with hypothyroidism]

Intra-abdominal infection complicated with hypothyroidism is very common. It mostly featured decreased T3, with or without decreased T4, and without elevated thyroid stimulating hormone(TSH). This particular type of hypothyroidism was called "low T3 syndrome" or "thyroid illness syndrome", and is called "non-thyroid illness syndrome" increasingly in recent years. Its pathogenesis has not been fully understood, and probably is associated with abnormality of hypothalamic-pituitary-thyroid axis, disorder of peripheral thyroid hormone metabolism, change in thyroid hormone binding protein, regulation of triiodothyronine receptors, effect of cytokines, and lack of trace element selenium. Intra-abdominal infection complicated with hypothyroidism should be differentiated from primary hypothyroidism, which may be one cause of mental depression, insufficient anabolism, and poor tissue healing. Therefore, the changes of T3 and T4 levels should be actively monitored in patients with severe or prolonged intra-abdominal infection. Whether treatment is needed for intra-abdominal infection complicated with hypothyroidism remains controversial. T3 replacement therapy may improve prognosis. When low T3 syndrome presents as a disease-mediated hypothyroidism, we recommend the use of levothyroxine(L-T4) or liothyronine (L-T3) treatment to improve the prognosis of critical patients. Enteral nutrition can improve hypothyroidism and has good efficacy for enterocutaneous fistula patients with intra-abdominal infection.