Growth Hormone Deficiency Prevalence After Traumatic Brain Injury in Adults
Growth hormone deficiency (GHD) occurs in approximately 37-52% of adult patients following traumatic brain injury, making it the most common long-term pituitary hormone deficiency after TBI. 1, 2, 3
Prevalence Data from Key Studies
The reported prevalence varies based on timing of assessment and severity of injury:
Acute to Chronic Phase Prevalence
At 12 months post-TBI: 37.7% of patients demonstrated GHD, with 50.9% having at least one anterior pituitary hormone deficiency 3
During post-acute recovery phase: 45% of patients had severe GHD (defined as peak GH ≤3 μg/L on provocative testing) 2
In chronic TBI patients with persistent symptoms: 52% were diagnosed with GHD when tested with the insulin tolerance test (ITT) 1
In patients with lasting cognitive/behavioral disorders: Severe GHD occurred in 40.0% of patients, with an additional 23.6% having partial GHD, totaling approximately 64% with some degree of GHD 4
Important Clinical Context
GHD is the most prevalent long-term pituitary deficiency following TBI, more common than deficiencies in corticotropin (19-27%), thyrotropin (10-30%), or gonadotropins (7-15%). 4, 3, 5
Dynamic Nature of Post-TBI Hypopituitarism
The prevalence changes over time, as pituitary function can both recover and deteriorate:
Recovery occurs in 57.7% of patients who initially had pituitary deficiencies within the first year 3
New deficiencies develop in 51.9% of patients during the first 12 months post-injury, even if initial testing was normal 3
This dynamic pattern necessitates serial testing rather than single-time-point assessment, particularly given that chronic GHD (15-20%) may not be apparent in acute phases 5
Clinical Implications
The high prevalence of GHD after TBI is clinically significant because it contributes to persistent post-concussive symptoms including physical and cognitive fatigue, cognitive inefficiency, metabolic changes, and psychological symptoms. 1
Patients with GHD demonstrate increased disability, decreased independence, and higher rates of depression compared to TBI patients without GHD 2
GHD is associated with attention and verbal memory disorders and reduced involvement in activities of daily living 4
Symptoms of GHD overlap substantially with TBI sequelae, making clinical diagnosis challenging without provocative testing 6
Diagnostic Considerations
IGF-1 levels alone are not predictive of GHD in TBI patients, requiring provocative testing (glucagon stimulation test or ITT) for definitive diagnosis. 2
Clinical markers that may suggest GHD in TBI patients include loss of libido, reliance on sleep aids, and feeling overweight, though these have only mild to moderate discriminatory power. 1