​Differential diagnosis of occult gastrointestinal bleeding

​Differential diagnosis of occult gastrointestinal bleeding 
-idiopathic 
-menstrual or pregnancy associated iron loss 
-malabsorption such as celiac sprue 
-inflammatory bowel disease
-drugs such as NSAIDS, aspirin 
-infection such as hookworm, tuberculosis
-ulcerated polyp 
-peptic ulcer disease
-portal hypertensive gastropathy 
-vascular ectasias / angiodysplasia 
-idiopathic arteriovenous malformation 
-CREST syndrome
-hereditary hemorrhagic telangiectasias
-malignancy