Posttraumatic hypopituitarism (PTHP) refers to any abnormality of the hormonal hypothalamic-pituitary axis following traumatic brain injury. Multiple factors are involved in the development of PTHP. Posttraumatic hypopituitarism is not limited to those with severe traumatic brain injury. Glucocorticoid deficiency is life-threatening, and in the acute intensive care setting a morning cortisol <300 nmol/L (11 μg/dL) is abnormal. Do not use the synthetic adrenocorticotropic hormone test to diagnose adrenal insufficiency in the acute phase. Growth hormone deficiency should be diagnosed using an appropriate dynamic test done by a pituitary endocrine center with established cut-offs and assays.