different Ferritin levels depending on doctor?

I had a blood draw for my sleep center to check ferritin levels. It came back as 6.9, and he said to start taking (2) pills a day (60 elemental iron each). I was surprised that my bariatric doctor (different hospital) hadn't said anything about being low, so I checked those records. For all the blood tests they have done (4 or 5 in the last year), the ferritin level was in the low 30's. How can that number be so different? My historical records (over 10 years) range in the 6-9 area, and that was done through the same hospital as the most recent 6.9. I don't know what to believe now. Thoughts? I see my bariatric doctor again in July and will ask about it. I'm 11 months out.

There are several different numbers that measure your iron. Are you sure you're looking at the same measure on the different reports?

Yes, Ferritin and the measurement units are the same also.

Regardless, all of those numbers are really low. Some alarmingly so. If it were me, I would get a referral to a hematologist, and have them test it -- and get an iron infusion.