When Jonathan Plummer told doctors he was drinking up to 10 litres of water each day, doctors assumed he had diabetes.
For extreme thirst is a tell-tale sign of the condition.
However, medics were baffled when the 41-year-old’s test results for diabetes came back negative.
Instead, the cause of the postman’s extreme thirst was a brain tumour located in his pituitary gland.
The pea-sized part of the brain helps regulate our sense of thirst, commanding us to drink when it detects we are getting dehydrated.
But in Mr Plummer’s case, the system went haywire and was instructing him to drink around four times more than the recommended amount every day.
Jonathan Plummer is preparing to do a charity skydive to help support research into brain tumours
It was only when he went for a routine eye test in 2002 that the mass was spotted and he was referred to Derriford Hospital for an MRI scan.
It revealed that he had a brain tumour, specifically a germ cell tumour.
Mr Plummer, from Falmouth in Cornwall, had to undergo 30 rounds of radiotherapy but is now tumour-free.
Recalling his ordeal, he said: ‘I felt a constant thirst that I couldn’t quench and got to the point where I was passing as much water as I was drinking.
‘It was an awful time which caused me to miss days of work at a time and I experienced extreme fatigue.’
Mr Plummer pictured here six months after medics found the cause of his intense thirst
He said he was ‘devastated’ at his diagnosis.
Mr Plummer was given steroid therapy as part of his cancer treatment, which had the side effect of causing him to pile on weight, going from 12st to 18st.
The treatment has, however, left him unable to play rugby and cricket, something he was a fan of before.
‘I was always very active and played rugby and cricket weekly which is something I have never been able to return to.
‘I took up running and swimming as non-contact exercise and have regained control of my weight.’
But he’s now on a mission to help raise money for the charity Brain Tumour Research through a sponsored skydive.
Mel Tiley, community development manager at the charity, said: ‘We’re grateful to Jonathan for sharing his story and it’s wonderful to hear how he has found positivity after his brain tumour diagnosis.’
‘His story reminds us that brain tumours are indiscriminate; they can affect anyone at any age.
‘We’re determined to change this but it’s only by working together that we will be able to improve treatment options for patients and, ultimately, find a cure.’
While not true in Mr Plummer’s case, increased thirst and urination are normally common symptoms of diabetes, a condition that causes a person’s blood sugar level to become too high.
Germ cell tumours develop in the body’s germ cells, which are usually located in the ovaries or testicles.
However, germ cells can sometimes be found in other parts of the body, such as the brain.
This is normally the result of germ cells being accidentally left behind as the body develops in the womb, before that person is even born.
According to Cancer Research UK there are about 12,000 cases of brain tumours diagnosed in the UK each year, with some 5,000 deaths.
Survival varies greatly depending on the specific type of tumour and its exact location in the brain with only 10 per cent of people diagnosed living longer than a decade.
