The immune checkpoint inhibitors (ICPi) revolutionize the cancer therapeutics, though not being devoid of toxicity. The immune-related primary adrenal insufficiency (PAI) is a rare, yet potentially life-threatening, adverse event, posing diagnostic and therapeutic challenges. We report the first case of reversible PAI related to nivolumab (programmed cell-death 1 protein inhibitor) in a 42-year-old male with metastatic rectal adenocarcinoma. PAI manifested as profound fatigue, disorientation, hypotension, hyperpigmentation of palmar creases, and hyponatremia without hyperkalemia 16 weeks after initiation of nivolumab. Due to impending adrenal crisis, intravenous stress doses of hydrocortisone and hydration with normal saline were initiated. When the state of patient was stabilized, PAI was confirmed through 250 μg Synacthen test 24 h after temporary cessation of hydrocortisone. Hydrocortisone was fixed at maintenance dose, while mineralocorticoid substitution was not required. PAI was ascribed to nivolumab based on history, physical examination, and laboratory work-up with emphasis on positivity of anti-21-hydroxylase antibodies and exclusion of other causes of PAI by normal imaging of adrenal glands on computed tomography (CT). Reevaluation of adrenal function during follow up demonstrated complete recovery. A review of literature concerning the immune-related PAI indicated that the complete recovery of adrenal function, the normal CT imaging, and the positivity of anti-21-hydroxylase antibodies observed in our patient are exceptional findings of immune-related PAI. Finally, heightened suspicion of immune-related PAI in case of hyponatremia without hyperkalemia and constant vigilance for diagnosis of rare, but real, reversibility of immune-related PAI are of paramount importance.

免疫检查点抑制剂（ICPi）彻底改变了癌症治疗方法，尽管它没有毒性。免疫相关性原发性肾上腺皮质功能不全（PAI）是一种罕见的但可能危及生命的不良事件，对诊断和治疗提出了挑战。我们报道了在42岁的男性转移性直肠腺癌中与nivolumab（程序性细胞死亡1蛋白抑制剂）有关的首例可逆PAI。PAI表现为在开始纳武单抗后16周出现严重的疲劳，迷失方向，低血压，手掌折痕色素沉着和低钠血症而无高钾血症。由于迫在眉睫的肾上腺危机，开始静脉注射一定剂量的氢化可的松并用生理盐水水合。当病人的状态稳定下来时，暂时停止氢化可的松治疗24小时后，通过250μgSynacthen试验确定了PAI。将氢化可的松固定在维持剂量，而无需盐皮质激素替代。根据病史，体格检查和实验室检查，PAI归因于nivolumab，重点是抗21羟化酶抗体的阳性反应以及通过计算机断层扫描（CT）对肾上腺的正常成像来排除PAI的其他原因。随访期间肾上腺功能的重新评估显示完全恢复。关于免疫相关PAI的文献综述表明，在我们的患者中观察到的肾上腺功能的完全恢复，正常的CT成像以及抗21-羟化酶抗体的阳性是免疫相关PAI的特殊发现。最后，