As someone who has used this repeatedly to good effect:
Be specific. “I need you to document in your notes for this visit that I brought up the possibility of celiac disease and you declined to order screening tests.”
Bring an advocate or witness. In many locations this is permitted by law as a patient’s right. (For example, in Oregon, disabled patients are permitted 3 “support persons” in the hospital, and must be permitted to have one person with them at all times during an emergency visit or hospital stay.) If you are not physically permitted to have a witness present, bring someone in by FaceTime. Doctors act differently when you have a witness.
You are, in the US, legally entitled to the entirety of your patient record, unredacted. A provider may not deny you a copy of your records bc you owe them money for other things. A provider may charge you a reasonable fee for copying or mailing your records but may not charge you for research or retrieval.
The only exception to the above is therapy notes. You aren’t entitled to that, at least not by federal law. You may have different rights under state law.
You are also entitled to correct your medical record in the US. If your doctor doesn’t put that note in your records, you have the right to add a Statement of Disagreement. “During this visit, I brought up the possibility of my symptoms indicating celiac disease and asked for a blood test to investigate this possibility. Dr. Butthead declined to order the standard celiac screening blood test. I asked for Dr. Butthead to document this in my record. Dr. Butthead did not do so.”
Many places now will give you an after visit summary or upload them to an electronic records app. Read it. You might catch errors (I have - doctors and nurses are people, they make mistakes). If they don’t give you a record or summary to take with you, request one.
If you are in the hospital without support and are being mistreated, ask for a patient advocate. If they don’t send you one promptly for whatever reason, ask to see a chaplain, or call your religious leader to ask for help. Having a witness changes how doctors act. Many chaplains are used to being asked to support patients who are not receiving proper care and will not be surprised if you explain “I asked for an advocate and they haven’t sent one; I’m not being listened to and I need your help.” This won’t always work but it’s worked often enough that I feel confident in recommending it.
I am white; I have never experienced medical racism. These steps and methods have helped me a lot in facing medical misogyny, fatphobia and transphobia, so I hope they help others. I am not a lawyer, this isn’t legal advice.
HHS Patient Rights & Protections