What are the Causes of Anemia in Rheumatoid Arthritis (RA)?

Causes of anemia in rheumatoid arthritis (RA): 

• Microcytic anemia due to iron deficiency secondary to NSAID-induced or steroid-induced gastrointestinal bleeding
• Marrow suppression from drugs such as penicillamine and gold
• Hypersplenism (increased red cell uptake and destruction by the spleen): it is seen as part of Felty's syndrome 
• Normocytic normochromic anemia (as anemia of chronic and active disease) 
• Macrocytic anemia (Folate deficiency resulting from increased cell turnover in chronic inflammation. Methotrexate also decreases folate level)
• Autoimmune hemolysis
• Associated pernicious anemia 

Sources:

• Rapid Review of Clinical Medicine for MRCP Part 2: Q-320
• Notes & Notes for MRCP by Dr Yousif Abdullah Hamad: 1245
• Davidson Principle and Practice of Medicine 24th Edition: 1030