Thousands of disabled people who suffer from progressively worsening conditions will face reassessment for their benefits this year, new figures show.
Campaigners and MPs are now demanding changes to stop those with such conditions being repeatedly reassessed to claim personal independence payments (PIP).
Between April and October, 3,500 people suffering progressive conditions rheumatoid arthritis, multiple sclerosis (MS), Parkinson's disease and motor neurone disease were reassessed for PIP, according to a written parliamentary question from Labour MP Madeleine Moon.
SNP MP Carol Monaghan said she was dealing with four cases in her constituency of people who suffer from MS being reassessed for PIP, despite their condition only getting progressively worse.
"MS is a progressive condition, they're never going to be any better than they are at the moment, so they should never be asked to go for a re-assessment," she told the Press Association.
"Some of these people are still able to walk to a certain extent, so they get themselves in just about, and then they're being told that 'you look fine'.
"That's like somebody ill going to a doctor and the doctor saying 'yeah, you're looking all right, I'm not going to bother doing any tests'.
"It's a medical condition - it's not about how somebody or somebody presents. It's actually about a diagnosis that's given by a medical professional, and this simply isn't happening."
In 2015/16 2,400 people with these conditions were reassessed for PIP, according to the figures obtained by Ms Moon, compared with a total of 200 in the previous two years.
Ministers say award reviews ensure people are getting the right level of support, and that these reviews could see their payments increased.
But Phil Reynolds, policy and campaigns adviser at Parkinson's UK, said the reassessment figures were "only the tip of the iceberg".
He added: "The cost of these pointless and wasteful reassessments for Parkinson's alone will be around £72,800.
"Recent figures show that around a quarter of people with Parkinson's have lost some or all of their support following reassessment from disability living allowance (DLA).
"Many have won the right to receive this again when this has gone to appeal. This is unacceptable, and further highlights a shambolic assessment process.
"It's absolutely crucial that the Department for Work and Pensions (DWP) looks again at the broken PIP assessment to ensure people with long-term conditions get the support they so desperately need, rather than rigging the system against them."
Similar concerns have been expressed by Laura Wetherly, policy manager for welfare and employment at the MS Society.
She said that under DLA, 78% of claimants with MS only faced reassessment every five years or more.
However, 47% of those claiming PIP have to be reassessed within two years.
"We're concerned about the number of people with MS being inappropriately reassessed, especially when we know assessments can cause stress and anxiety, and in some cases exacerbate MS symptoms," Ms Wetherly added.
"With more than 100,000 people living with MS in the UK, the PIP system needs to accurately reflect the realities of living with a fluctuating and progressive condition.
"Having a disability like MS is hard enough; people should be able to rely on support without fear of having it taken away."
DWP has already scrapped assessments for the chronically ill every six months to qualify for employment and support allowance.
A DWP spokeswoman said: "Under PIP, 27% of claimants are now receiving the highest rate of support, compared to 15% under DLA, with a greater proportion of Parkinson's and MS claimants receiving the highest possible rates for daily living expenses.
"Assessments are carried out by qualified health professionals who combine their clinical knowledge with an understanding of the fact that not everyone with the same disability is impacted in the same way.
"PIP is an interactive benefit, designed to ensure any changes in a claimant's functional ability can be identified and that they receive the right support at the right time."
The length of a PIP award is based on an individual's circumstances and can vary from nine months to an ongoing award with a light touch review after 10 years.
Those who suffer from the most severe disabilities are more likely to have their benefit reviewed without the need to have another face to face consultation, the spokeswoman added.