There are thousands of head injuries in the UK every year.
Every year, around 1.4 million people attend hospital A&E departments in the UK following a head injury. Around 200,000 people will be admitted because of the severity of their injury. 
Around a quarter of head injury survivors suffer pituitary damage
Around 20-30% of survivors of traumatic brain suffer from hypopituitarism . According to BBC’s Inside Health’s programme there are between half a million and a million undiagnosed sufferers,  which suggests that most cases remain undiagnosed and untreated. The symptoms include growth failure, delayed or arrested puberty, failure to have periods or reduced libido , difficult in concentrating  and fatigue  and depression . 10-17% of long-term TBI survivors suffer from impotence . Obviously, cases of delayed puberty and growth failure are diagnosed, but reduced libido, difficulty in concentrating and fatigue, depression and impotence, may never be mentioned to the GP, never mind diagnosed correctly as pituitary damage. As well as these effects hypopituitarism may cause osteoporosis  and cardiovascular disease .
It may not show itself immediately
Symptoms of pituitary damage will not necessarily appear immediately. "Some develop hypopituitarism many years after the initial event." 
It is treatable
This condition is treatable with hormone therapy. Depending on which deficiency is being treated, the benefits of treatment  include improved sexual function, stronger bones, better quality of life and, according to some studies, improved cardiac function. Other research  reports that replacing growth hormone improves cognitive function. Testosterone replacement in hypogonadal men has resulted in decreased anger and irritability, and increased libido and energy .
Head injured people are not warned
Head-injured patients are still being discharged from hospital with no inkling of what may lie in wait. Even the National Institute for Clinical Excellence guideline on the treatment of head injury gives no warning in the 'discharge letter' they suggest for use for patients leaving hospital.  However it is likely that NICE will include a warning in their revised head injury guideline due to be published in 2022.
Head injured people are at risk of committing suicide
These people are at risk of committing suicide. An Australian study by Simpson and Tate  says that out of 178 head injury survivors they monitored, 18% attempted suicide and 35% had clinically significant levels of hopelessness. This is borne out by the Pituitary Foundation's Needs Analysis Report in 2006*. The suicide rate for head-injury survivors, according to a large epidemiological study, is up to four times that of the general population .
The government wishes to cut suicides
There are 4,500 suicides a year in England . In 2012 the British Government published its National Suicide Prevention Strategy for England, updating it in 2017 and following it with a Cross-Government Suicide Prevention Work Plan, which unfortunately does not highlight the high suicide risk of those with past head injuries. The onus is on the individual to seek help if symptoms suggest hypopituitarism, and to be persistent if necessary.
For more information on the effects of head injury see http://www.headway.org.uk
Finally, a note about sports injuries
There is much debate about the likelihood that repeated concussions and head injuries cause chronic traumatic encephalopathy (CTE) and Alzheimers. It is worth remembering that sports concussions cause hypopituitarism too, and whereas little can be done at present to treat CTE and Alzheimers, thousands of sportspeople and athletes could be helped with hormone replacement therapy.   . This article by Dubourg  concludes that “Current knowledge clearly supports the proposition that sports, especially combat sports, are a cause of hypopituitarism, particularly isolated GH deficiency. Therefore, the medical community should be aware of this, and participants in sports who were exposed to chronic repetitive TBI should be screened. However, further multicenter and multidisciplinary studies are required to explore the details of pathophysiological mechanisms and to produce accurate prevention recommendations and guidelines on hypopituitarism in sports-related head trauma.”
*Morris M, Jackson S, Needs Analysis Report for Pituitary Foundation, Oct 2006. [This report is not available on line]