Altered gut microbiome and post traumatic hypopituitarism in chronic TBI: The need for recognition, evaluation and...

Post traumatic hypopituitarism (PTHP) occurs in 30-50% of individuals with chronic moderate-severe TBI as well as individuals with mild TBIs who remain symptomatic after a year. Growth hormone deficiency (GHD) occurs in approximately 15-20%, Gonadotropin deficiencies in 10%, as well as Thyroid and Adrenocorticotropin deficiencies in 4-12%. Individuals frequently have more than one deficiency. These numbers cover a wide range and vary based on time of testing, cut-points and methods used. Recent studies have shown hypoaminoacidemia and altered gut microbiome in a subset of individuals with mTBIs with subjective complaints of fatigue and altered cognition: Brain Injury Associated Fatigue and Altered Cognition (BIAFAC). These individuals may become symptomatic months to years after the injury and frequently have a diminished response to growth hormone stimulation testing, although not always below the established cut points for Growth Hormone Deficiency (GHD). Recognition of BIAFAC for its similarities and differences from PTHP by physicians dealing with TBI will lead to more thorough evaluations and may eventually lead to better treatment options for these individuals. This paper will begin with a discussion of the relevance of anatomy to post -TBI changes, and how hypoaminoacidemia may play a role in the symptoms after TBI.