BackgroundWith the increasing application of immune checkpoint inhibitors (ICI) in cancer therapy, the occurrence of isolated adrenocorticotropic hormone deficiency (IAD), as an adverse effect, is also on the rise. Nevertheless, there are only a few studies regarding IAD induced by ICI. This study aimed at investigating the characteristics of IAD induced by ICI and its relationship with other endocrine adverse events.MethodsA retrospective study was conducted in the Endocrinology Department from January 2019 to August 2022 to investigate characteristics of patients with IAD. Clinical features, laboratory findings and treatment information were collected. All patients underwent a follow-up of 3-6-month.Results28 patients with IAD were enrolled. All patients received treatment with anti-PD-1/ PD-L1. The median occurrence time of IAD was 24 (18–39) weeks after initiation of ICI treatment. Over half of the patients (53.5%) had an additional endocrinopathy, including primary hypothyroidism and fulminant type 1 diabetes mellitus (FT1DM), while other types of endocrinopathies were not identified. The interval between the occurrences of two gland damages was between 4 and 21 weeks or simultaneous. Primary hypothyroidism (46.4%) was more prevalent than FT1DM (7.1%). Fatigue and nausea were common symptoms, with a frequent occurrence of hyponatremia. All patients continued on oral glucocorticoids during follow-up.ConclusionsIAD induced by ICI could manifest independently, or more frequently in combination with hypothyroidism or FT1DM. This damage could happen at any point of ICI treatment. Given that IAD can be life-threatening, it is critical to evaluate pituitary function dynamically in patients undergoing immunotherapy.