@kathleen1314 I am so appreciative of your reply! It rounds out the picture which is getting clearer to me. No one really knows enough because there simply isn't much reported experience or study to say. Based on what you presented and what I've found using sites like consumerlab.com, it seems as if MK-4 MIGHT be okay but only a doctor knowledgeable about K2s will help you establish how best to proceed. Since my oncologist, cardiologist, and electrophysiologist all seem unfamiliar with the various K2s, that's a bit of a problem. I see one more cardiologist who specialized in oncology next week and will see what, if any advice, she has. One resource I haven't tried yet is my pharmacist.

I think the use of INR is largely used when doctors prescribe warfarin. It does not appear to be used by most cardiologists (at least mine) when prescribing a DOAC. Since I'm a challenging needle stick and rely on my port, more blood tests aren't something I'd like to add.

One of your referenced websites (www.myheartdisease.com) says "However, research is still limited on high-dose vitamin K2 supplements and their interactions with these medications."

That suggests to me that the Japanese dosage of 45 mg/day of MK-4 would be excessive for someone like me. But I'm tempted by the idea of one dose of 15 mg/day of MK-4. Although not the prescribed dose for treatment in Japan, it still might provide a bit of help.

I'm also appreciative that you mentioned copilot AI which I'm not familiar with. The one AI I'd like to try is Claude so decided now's the time. This is the bottom line from Claude:

"Based on current evidence, MK-4 is unlikely to interfere with Eliquis, and this combination is generally considered lower-risk than vitamin K with warfarin. However, I'm not a doctor, and individual health situations vary. It's still worth a quick conversation with your prescribing physician or pharmacist before adding it — especially if you're taking Eliquis for a serious condition like AFib or clot prevention. They can give you a green light with confidence."

I will also go back and research possible interactions between strontium citrate and my prescriptions which are quite the list now. I don't recall why I stopped. Ease of use and timing might have been issues too. I can't swallow pills so have to open large capsules and mix them with something non-dairy.

My thanks again for your consistently well-researched and thoughtful and timely response. You are wonderful and so much appreciated in this online community!