There is no quick or easy way to do this. It requires a good job reviewing everything. Bipolar is often misdiagnosed as something else a couple of times before it is seen for what it is…
About 10 years ago, I saw a big spike in questionable bipolar diagnoses, but it has seemed to have subsided in my corner of the world.
When I saw them, there was a definite reliance on the “ups and downs” or moodiness conversation.
Generally, the ones that I disputed as still being explained by ADHD followed a very predictable pattern in how their morale, frustration, workload, etc. cycled throughout a semester. You could see a very clear cause-effect on how ADHD symptoms impacted their life and, therefore, their mood, feelings of helplessness, etc.
The one time that I have pushed for a bipolar diagnosis over ADHD, I was clearly able to charter on a graph what looked like manic and depressive episodes on a timeline with labels on what was happening at school and home. The ups and downs were very clearly unrelated to what was going on externally.
Ask a million questions as to the rationale and differentiation. Is the clinician ready, willing, and able to answer your inquiries with patience and plain English? Is it “because I am the professional”?