系统性红斑狼疮（systemic lupus erythematosus，SLE）继发免疫性难治性血小板减少症（immune thrombocytopenia，ITP）以持续严重血小板减少和出血征象为主要特征，目前尚无标准的治疗方案。本例患者为34岁男性，有10余年贫血及血小板减少病史，入院后诊断为SLE。患者先后接受过多种免疫抑制剂治疗，包括泼尼松、环孢素、吗替麦考酚酯、硫唑嘌呤和靶向制剂托法替布与泰它西普，均无明显疗效，血小板计数持续低于50×10⁹/L。全程监测环孢素的血药浓度来优化环孢素的给药剂量，并监测环孢素的疗效和不良反应。环孢素谷浓度维持在100~150 ng/mL，血小板计数维持在100×10⁹/L以上，达到临床缓解，随访6个月未出现不良反应。环孢素联合小剂量糖皮质激素治疗SLE继发难治性血小板减少症安全有效，治疗药物监测有助于提高药物的临床疗效，减少不良反应。

Systemic lupus erythematosus （SLE） complicated refractory immune thrombocytopenia （ITP） is mainly characterized by persistent severe thrombocytopenia and bleeding. Currently， there are no guidelines for treating such ITP. Hereby we reported a patient diagnosed with SLE with more than 10 years history of anemia and thrombocytopenia. This patient had been treated by various immunity inhibitors， such as corticosteroids， cyclosporine， mycophenolate mofetil， azathioprine， tofacitinib and telitacicept， but there was no obvious effect. The platelet count continued to be below 50×10⁹/L. However， when serum cyclosporine trough level between 100 and 150 ng/mL， the clinical efficacy was improved and the platelet count was above 100×10⁹/L. The patient was followed up for more than 6 months， and no recurrence of disease was found. Cyclosporine combined with low-dose glucocorticoid is safe and effective for SLE associated ITP. Therapeutic drug monitoring is a powerful tool for improving clinical efficacy and ensuring drug safety.