At first glance, it might seem like any worker who is disabled would want his or her employer to be aware of this fact. After all, while disabled people aren't after special treatment, there are circumstances that make it necessary to have accommodations made for them so that they can do their job at the same high level as their co-workers.
This isn't as clear-cut as it might seem, however. An employee might not to reveal a disabling condition for personal reasons -- and, sometimes, to avoid any kind of special accommodation that would make the situation seem unfair to co-workers.
In some cases, what are disabilities from a practical standpoint, and in the eyes of U.S. law, can be all but invisible. Something like cancer or post-traumatic stress disorder might not affect someone in a dramatic sense, so a co-worker might not even be aware of it. Sometimes, though, these conditions could be severe enough to qualify for benefits under Social Security disability if they render a person unable to work.
For those people who are working, and who want to work as long as they are physically able, what is the best way to go about explaining their situation? Many workers might choose to avoid disclosing it at all. While it might be the seemingly easiest way, it can have serious consequences. If a worker cannot perform duties as requested, and the employer doesn't know that it's because of a disability, it could lead to discipline or even termination.
Source: NIU Today, "Why some workers don’t disclose their disabilities," June 17, 2014