A high thyroglobulin level of 300's does not necessarily mean Hashi -- maybe this was a thyroglobulin antibody or there was a TPO antibody. Post-partum onset of autoimmune thyroid disease is common so this may well be the right diagnosis.
The primary thing to rule-out as a connection between Hashi and iron/Vit D deficiency would be celiac sprue (gluten sensititvity) -- can be done with blood tests as well as a small bowel biopsy. Would ask the GI doc doing the endoscopy about this possibility if it is not already being considered.
Hashi does not cause low ferritin. In young menstruating women the most common cause is the menstrual bleeding. I don't think IBS causes low ferritin. More serious cases usually have low iron as well and anemia. This is not likely cancer.
When the colonoscopy was performed I also did a blood test to rule out celiac & the dr. said my results were normal. Could irritable bowel cause this? I am not low in Iron just the ferritin & I bruise very easily.
Can Hashimotos cause the ferritin deficiency? My anxiety symptoms are pressure in head, hyperventilation syndrome, palpitations & I don't get panic attacks anymore because I learned what they were. I am sorry to ask you again about this but I am scared as to what the cause of low ferritin is. Can cancer also cause this?