Post-traumatic hormonal disturbances: prolactin as a link between head injury and enhanced osteogenesis

Traumatic brain injury (TBI) combined with fractures of long bones or large joints is often associated with enhanced osteogenesis (early fracture healing accompanied by hypertrophic callus formation and/or heterotopic ossifications). Humoral factors that cause enhanced osteogenesis in patients with TBI are not yet identified. The aim of this study was to reveal if post-traumatic change(s) of hormone levels in patients with TBI and bone fractures could be associated with the phenomenon of enhanced osteogenesis. The blood values of adrenocorticotropic hormone (ACTH), cortisol, growth hormone (GH), parathyroid hormone (PTH) and prolactin (PRL) were studied weekly over a period of three months after injury in patients with bone fractures only, those with TBI only or combined bone fractures and TBI (patients exerting enhanced osteogenesis). Stress-hormones, ACTH and cortisol, or the hormones related to the bone growth (GH and PTH) did not show any particular post-traumatic changes in the blood of patients with combined injury that could be associated with the enhanced osteogenesis. On the other hand, patients with combined bone fractures and TBI accompanied by enhanced osteogenesis had significantly elevated PRL levels in blood during the 5th week of the post-traumatic period. Thus, the maximal PRL values were measured at the time when in this group of patients fractures were in consolidation and hypertrophic callus or heterotopic ossifications were developing (as verified by x-ray imaging). Hence, PRL does not only influence physiology of the bone metabolism but also seems to be one of the humoral factors involved in the phenomenon of enhanced osteogenesis in patients with TBI.