I had ulcerative colitis but also had inflammation in duodenum. It causes deficiency of vitamin b12, d, iron and hair loss. What could be reason for it??

Vitamin. colitis can cause degrees of malabsorption if that's the case you can be vitamin deficient this could cause B12 Folic Acid and other vitamin deficiencies which might contribute to your hair loss or other medical problems seek medical care with your internist or gastroenterologist good luck.