How unfortunate that you're going through this.
I need a little more info. Who ordered the urine test? Are you having regular urine tests, and if so, for how long? I'm assuming this has never come up before now, a test not showing the med? Are you by chance getting the Xanax through a pain management doctor? Many times, they will require occasional or regular tests to verify you are indeed taking the meds they prescribe, and for many different reasons, from lab error, to half life as GL has explained, to a whole host of others, the med may not show, despite you taking it.
Any other background you can give would be super helpful. Who is Rx'ing the Xanax, what is your dose, and how long have you been on it? Other meds you are taking? Are you on SSI for disability? You may have some options here, depending on the situation.
Unfortunately, you being a US citizen on SSI doesn't mean you can demand anything. Right or wrong, Xanax is a controlled substance that requires a physician's DEA # to prescribe it. They can always use their own judgement and cease prescribing it if they are suspicious of misuse, abuse, or misappropriation of meds. Pain management docs often require their patients to sign lengthy contracts that include verbiage about testing and their right to discharge you as a patient at any time, and stop Rx'ing your meds without any notice, at their discretion. Again, it may not be right, but it's the way of the world, and if you think about it, they are only protecting their license and DEA #. If you've never had any issues prior to this with this doc, they really should be willing to give you a retest. That's not to say they will...some are real hard a$$es.
Please share some additional info, and we may be able to give you more specific advice.
Depending how long you've been on Xanax and at what dose, any doctor with the slightest knowledge of psychotropic meds knows you can not just simply stop taking Xanax...........there can be extremely serious medical reactions like seizures.
How long was it between your last dose of Xanax and the urine test?
Xanax has a half-life of 12-15 hours, which means that every 15 hours, 1/2 of the amount of Xanax in your system is eliminated. For example, if you were taking 4mg of Xanax and stopped abruptly, in 15 hours, there would only be 2mg in your symstem. 15 hours later there would only be 1mg, 15 hours more and you'd be down to 1/2mg and so on until it was totally out of your system.
That MAY be a reason they found none in your urine.
I really don't know the best way for you to fight this. Was it SSI who denied the claim or is it your doctor denying refills? I'm sure you could file a complaint with SSI, but that process would probably take YEARS. Can you get a second opinion? If it wasn't the doctor who denied you refills, perhaps he can help you fight the SSI people. Many senior centers have legal advice available for free or a very nominal charge. If you are a Veteran, perhaps they can help? Your pharmacist may have some thoughts on where to get help since they deal with the insurance companies all the time.
Hopefully, someone else on this forum will know exactly what you should do.
I'm sorry this is happening. It's not right nor is it fair. Don't give up searching for answers and let us know what you find out. You can't be the only one in this position and perhaps we can help you find out how to get in touch with other people who have fought this battle.
Peace
Greenlydia