PTSD is caused by exposure to stressful events and can lead to anger, aggression, flashbacks, sleeplessness and a range of other mental and physical health issues.
It follows figures from NZDF showing there have been five suicides in the past two years, against five in the previous eight years.
New Zealand's military partners are having fallout from years of combat in Afghanistan with increased mental health problems and a soaring suicide rate among veterans.
An NZDF statement put the low level of reporting down to troops experiencing less combat, the "stoic New Zealand culture" and the lack of "financial advantage to obtaining a diagnosis of PTSD in New Zealand".
The statement said NZDF's understanding of PTSD related to combat operations was not as well developed as that of the United Kingdom or the United States because of the low number of cases reported.
The Weekend Herald sought data from Veterans Affairs on contact from those who had sought help from the military for PTSD after leaving.
Secretary for War Pensions Rick Ottaway said no information was kept showing contact by veterans.
He also said no information showing "disability by deployment" was kept on pension files.
Rannerdale Veterans Care hospital manager Stephen Shamy said PTSD often did not emerge until years after an incident.
He said an increased focus on veteran care was needed, as PTSD often did not appear until years after soldiers left the military.
He said the military culture tended to suppress reporting of PTSD because it affected career opportunities and relationships with peers.
The issue was one which needed to be raised in the year the centennial anniversary of World War I was being marked.
"The science of medicine has advanced greatly - and what we haven't learned is to deal with the mental trauma."
The estimate of deployed staff comes from the Defence White Paper, based on figures for 2003-2009 missions which show 7875 staff were posted abroad. NZDF reported another 10 incidences of PTSD which were categorised as relating to domestic incidents.
Help lacking - ex-soldier
A former Kiwi soldier who served in Afghanistan says little mental health support was available when he was in the combat zone.
But he also says help was available once troops were back in New Zealand, even if it wasn't sought out for fear of damaging career opportunities.
The former soldier, speaking anonymously, said soldiers in Bamiyan relied on each other for support. A padre was available but no formal mental health care support.
"Soldiers are stoic and having PTSD (post traumatic stress disorder) would be perceived as a sign of weakness or even an excuse to get out of work. To my knowledge there was no mental health professional on deployment so if you had a problem you would keep it to yourself or discuss it with your peers."
After leaving Afghanistan, soldiers would meet a psychologist - usually in Dubai - while returning to New Zealand.
The meeting with the psychologist included preparing soldiers for returning home.
He said many went on leave and needed help to cope with returning to normal life and the difficulty of "being away from the mates they consistently relied on".
Help was available on returning to domestic military life but it relied on soldiers seeking it.
"Most soldiers would avoid going to a psychologist because of the stigma associated with having mental issues."
He said the self-reporting aspect was also difficult because "having PTSD would show up on your file and can affect your career progression ..." David Fisher
