More testing required?

I know this forum is not very active, but I thought I'd give it a shot anyway.

My doc was checking my thyroid levels and apparently threw in a metabolic panel out of habit. Turns out my eGFR came back super low at 45. It was completely normal in September. I am a 37yr old female. No diabetes or hypertension. All the diabetes tests that would indicate an issue have always been normal. I've never had high blood pressure. It's usually low to low normal actually. No history of kidney issues in the family.

I have Hashimoto's thyroiditis and recently started an autoimmune diet protocol. That was in October and I'm still on it. It's low carb in nature, though not like Atkins. There is a fair amount of protein, but veggies and fat are the more critical things. I am terrible about drinking enough water. Just awful. I've lost a fair amount of weight in that time as well even though I was not overweight to begin with.

My doc was alarmed when she first got the results back. She emailed me and let me know there was a concern and that I should get a 24hr urine test. However, I later spoke to her and after hearing about my weight loss, the diet (which she was aware of), and my poor fluid intake, she was no longer concerned. She believes those factors are the cause since only 4mos ago they were completely normal and the change lines up with new diet. Oh, and creatinine and BUN were completely normal. So she wants me to follow up in 3mos with another test, but I asked her to do it sooner and she agreed. So I'll do it again in 3-4wks just for peace of mind. I have ZERO risk factors.

The autoimmune diet is helping me actually. My thyroid values are improving, I feel more energetic, I joined a gym, etc. I just can't find too much online that says a low value can be benign.

Thanks for your input.