Azathioprine (Imuran®) 為一免疫抑制劑，廣泛使用於器官移植或自體免疫疾病的病患。臨床上常作為治療全身性紅斑性狼瘡、重度風濕性關節炎、預防腎臟移植手術排斥之藥物。骨髓抑制是azathioprine 眾所週知的副作用，例如巨紅血球症 (macrocytosis) 及輕微的白血球減少症 (leucopenia) 是很常見的副作用；較少見的副作用則包括貧血、血小板減少 (thrombocytopenia) 及全血球減少 (pancytopenia) 之機率則小於1%。單純紅血球再生不良 (pure red cell aplasia, PRCA) 則為相當罕見的副作用。
本文探討一位僵直性脊椎炎的病患服用azathioprine 導致全血球減少症之個案。病患在使用azathioprine 一個月後，其白血球、紅血球及血小板之數值，即有下降之趨勢，且在停藥後，情況更加惡化，並有出現感染症狀，隨後入院治療，並於停藥兩週後情況好轉。
藉由文獻回顧，本文探討此案例之azathioprine 引發全血球減少症之成因、可能性及因應處理方式。
 

Azathioprine is an immunosuppressive agent for auto-immune disease and solid organ transplantation. It is usually used for the treatment of systemic lupus erythematosus, severe rheumatoid arthritis, and preventing renal transplantation rejection. Bone marrow suppression is a well-known major adverse event of azathioprine.The common adverse drug reactions (ADR) of azathioprine include macrocytosis and leucopenia. Anemia,thrombocytopenia, and pancytopenia are rare ADRs, incidence lower than 1%. Pure red cell aplasia is a very rare ADR reported in azathioprine users. We reported a patient developing pancytopenia prescribed azathioprine for ankylosing spondylitis. This patient was reported as the value of white blood cell count, red blood cell count, and platelet count dropped gradually after a month taking azathioprine. Therefore, the physician withdrew this medicine immediately. However, patient’s condition was getting worse and had infection symptom. This patient then was admitted in the hospital for infection treatment and supportive care soon and recovered in two weeks. We discussed the reasons, possibilities, and treatment for azathioprineassociated pancytopenia by literature review.