I replied to your email on this topic, but for the sake of those who visit the message board, I want to post my response to you here as well so others can see.
First, generally health insurance in the U.S. is subject to the protections of the Patient Protection and Affordable Care Act (aka "Obamacare"). One provision of that law is that health insurance cannot deny coverage due to pre-existing conditions. However, there are exceptions. The supplemental Medicare coverage you applied for is one example. "Guaranteed acceptance," where you are provided coverage regardless of your age and health, occurs at your initial Medicare enrollment (generally at age 65). After that, if you add or change coverage, you're subject to underwriting (i.e., the insurance company can deny you coverage or charge you higher rates based on your health).
There are two other types of health insurance that can have pre-existing condition exclusions. One is supplemental medical insurance, sometimes called "indemnity" coverage or voluntary insurance coverage. This is coverage provided by companies like AFLAC that pay a set amount of money to the insured (not the provider) in the event of an illness or injury. The other type is "short term" or "temporary" insurance, which is intended to provide limited (and inexpensive) coverage as a bridge between more complete coverage.
Note that there is no protection from pre-existing condition exclusions for life and disability insurance.
Second is the issue of what constitutes "normal" biometrics (creatinine, BUN, GFR, etc.) for someone who is a living kidney donor. Everyone knows our kidney capacity is diminished by virtue of donating a kidney to someone else. The result can be numbers that make it appear we have kidney disease. But what if that remaining kidney is perfectly fine and we are otherwise in excellent health? Are we really at risk? Are we really uninsurable?
Unfortunately, there isn't an answer right now. There have been "discussions" in the medical community but no action, and I'm not aware of any comprehensive, definitive study that shows LKDs can be considered healthy even if their kidney biometrics are "abnormal."
Your experience of having health insurance denied is a prime example of the consequences of not having an answer to the question. That kind of consequence is also something that is rarely mentioned in detail in educational information used for "informed consent" of potential donors. It seems reasonable to insist on getting an answer in order for future donors to be considered truly informed of the longer term consequences of donation.
So what to do? As we discussed, I'll work on seeing what research is out there that might provide an answer, even if just a partial answer. I'll dig into the message threads we've had on this message board in the past on this topic to see what we can learn. I'll reach out to other LKDs to see what their experiences have been, specifically whether they have been denied coverage because of "abnormal" kidney biometrics while otherwise being healthy. And I'll contact other LKD advocates to get their perspectives and suggestions.
Stay tuned!