Levels dropped after starting shots?

Hello everyone,

My rheumatologist is a bit stumped. In October 2024 we discovered I have a B12 deficiency as I was at around 200. I started sublingual supplementation and at the end of November I was at 383 and then by January I was up to 538.

She was shooting for around 1000, so we started monthly injections, and stopped sublingual supplementation. I had had 4 injections, the last one 10 days before my last blood test in May, and my level dropped back down to 384. So, I’m starting supplementing again from today along with continuing the shots.

I was curious if anyone had any idea what the issue might be?

Thanks!