Effect of recombinant growth hormone replacement in a growth hormone deficient subject recovering from mild traumatic brain injury: A case report

Objective: To assess the effects of growth hormone (GH) replacement in an individual who sustained mild traumatic brain injury (mTBI) as an adult and was found to have GH deficiency by glucagon stimulation testing. Participant: A 43-year old woman who sustained a mild TBI at age 37 years. She was 6.8 years post-injury when she began supplementation. Intervention: Recombinant human GH (rhGH) subcutaneously per day for 1 year. Main outcome measures: Single fibre muscle function was evaluated from muscle biopsies. Body composition, muscle strength and peak aerobic capacity were also measured. In addition, neuropsychological tests of memory, processing speed and motor dexterity and speed, as well as a self-report depression inventory were administered. All assessments were performed at baseline and after 6 and 12 months of rhGH replacement therapy. Results: Single muscle fibre changes were greatest at 6 months. Body composition showed continuous improvement. Muscle strength improved for knee extension. Peak oxygen consumption increased at 6 months and total work and ventilatory equivalents continued to improve at 12 months. Significant improvements in neuropsychological test performance were not found, with the exception of performance on a test of motor dexterity and speed. Conclusion: rhGH replacement in a subject with GH deficiency after mild TBI improves muscle force production, body composition and aerobic capacity. Reliable improvements on tests of cognition were not found in this subject.