Idiopathic isolated adrenocorticotropic hormone deficiency: a systematic review of a heterogeneous and underreported disease.

Isolated adrenocorticotropic hormone deficiency (IAD) is considered to be a rare disease. Due to the nonspecific clinical presentation, precise data on the prevalence and incidence are lacking. In this systematic review, we aimed to analyse the clinical characteristics, association with autoimmune diseases, and management of acquired idiopathic IAD cases. A structured search was conducted after developing a search strategy combining terms for acquired (idiopathic) IAD. Articles describing an adult case with a diagnosis of ACTH deficiency using dynamic testing, no deficiency of other pituitary axes, and MRI of the brain/pituitary protocolled as normal, were included. Exclusion criteria were cases describing congenital IAD, cases with another aetiology for IAD, and articles where full text was not available. In total 42 articles were included, consisting of 85 cases of acquired idiopathic IAD. Distribution by sex was approximately equal (F:M; 47:38). Lethargy was the most common presenting symptom (38%), followed by weight loss (25%), anorexia (22%), and myalgia/arthralgia (12%). Eight cases (9.5%) presented with an Addison crisis. 31% of cases had an autoimmune disease at diagnosis of which Hashimoto hypothyroidism was the most frequent. Data about follow-up was scarce; dynamic testing was repeated in 4 cases of which 2 showed recovery of the adrenal axis. We report the largest case series of acquired idiopathic IAD to date. Our systematic review highlights the lack of a clear definition and diagnostic work-up. Based on the findings in this review a proposition is made for a flowchart to diagnose acquired idiopathic IAD.

Hypophysitis Induced by Sintilimab in the Treatment of Bladder Cancer: A Case Report.

BACKGROUND: Immune checkpoint inhibitors (ICIs), as novel antitumor drugs, have been widely used in the clinic and have shown good antitumor effects. However, their widespread use has also led to the emergence of various immune-related adverse events (IrAEs). Hypophysitis is a rare but serious IrAE. Due to its complex and changeable clinical manifestations, hypophysitis may be easily overlooked, leading to delayed diagnosis and treatment. CASE PRESENTATION: A 68-year-old male patient was diagnosed with bladder cancer (T2bNXM0) in October 2021. He received two cycles of immunotherapy with sintilimab and chemotherapy with gemcitabine and cisplatin (GC). One month after the second treatment, he gradually developed recurrent fever, anorexia, drowsiness, and delirium. Laboratory examination revealed hyponatremia, decreased adrenocorticotropic hormone, and hypocortisolemia. The pituitary MRI showed no abnormality. The patient was diagnosed with immunotherapy-induced hypophysitis (IH) caused by sintilimab, leading to downstream endocrine disorders. With hormone replacement therapy, he was in a good mood, had a good appetite, and made an overall recovery. CONCLUSION: Immunotherapy-induced hypophysitis (IH) can result in a severe adrenal crisis, and prompt recognition and diagnosis are crucial. Clinicians must remain vigilant for the possibility of IH in patients who exhibit recurrent fever, anorexia, cognitive decline, and personality changes following ICI treatment. It is imperative to consider this diagnosis early to initiate appropriate management promptly.

Hypothyroidism With ACTH Deficiency During Pembrolizumab Therapy for Lung Cancer: Case Report and Literature Review.

BACKGROUND/AIM: Immune-checkpoint inhibitors have recently shown great promise in treating various cancers, but often cause immune-related adverse events (irAEs). Simultaneous drug-induced hypothyroidism and isolated adrenocorticotropic hormone (ACTH) deficiency are rare irAEs. This combination of irAEs is associated with paradoxical endocrine dysfunction characterized by large amounts of thyroid-stimulating hormone (TSH) and small amounts of ACTH in the anterior lobe of the pituitary. We herein report a case of hypothyroidism with isolated ACTH deficiency during pembrolizumab therapy for recurrent lung cancer. CASE REPORT: Our patient was a 66-year-old man with recurrence of squamous cell lung carcinoma. Four months after chemotherapy that included pembrolizumab, the patient presented with general fatigue and laboratory tests showed high concentrations of TSH with low concentrations of free-T4. He was diagnosed with hypothyroidism and levothyroxine was prescribed. His ACTH concentration was found to be low 1 week later when he developed an acute adrenal crisis with associated hyponatraemia. We then changed his diagnosis to concurrent hypothyroidism with isolated ACTH deficiency. His condition improved after 3 weeks of administration of cortisol. CONCLUSION: It is difficult to diagnose a concurrent paradoxical endocrine disorder, such as hypothyroidism with isolated ACTH deficiency, as in the present case. Physicians should pay attention to symptoms and laboratory data to identify various types of endocrine disorders as irAEs.

Acquired idiopathic isolated ACTH deficiency with associated autoimmune thyroiditis in pediatrics: case report and review of the literature.

OBJECTIVES: Isolated ACTH deficiency (IAD) is defined as an impaired secretion of ACTH from the pituitary gland without any other anterior pituitary hormonal deficits. The idiopathic form of IAD has been described mainly in adults and is thought to be caused by an autoimmune mechanism. CASE PRESENTATION: Herein, we present an 11-year-old _prepubertal previously healthy boy, who suffered a severe hypoglycemic episode short after the initiation of thyroxine for autoimmune thyroiditis and was finally diagnosed with secondary adrenal failure due to idiopathic IAD, after all other etiologies were excluded, thought an extensive diagnostic work-up. CONCLUSIONS: Idiopathic IAD is a rare entity of adrenal insufficiency in pediatrics that should be considered as an etiology of secondary adrenal failure in children, when clinical signs of glucocorticoid deficiency are present and other causes are excluded.

Isolated Adrenocorticotropic Hormone Deficiency Associated with Atezolizumab and Bevacizumab Administration for Treating Hepatocellular Carcinoma: A Case Series.

Atezolizumab and bevacizumab are currently available as first-line treatments for unresectable hepatocellular carcinoma, but immune-related adverse events are a major concern. We herein report two cases of isolated adrenocorticotropic hormone (ACTH) deficiency. Both patients presented with general fatigue, appetite loss, eosinophilia, and hyponatremia after nine cycles in case 1 and three months after stopping treatment for inflammatory arthritis in case 2. Endocrinological investigations revealed unsatisfactory ACTH and cortisol responses despite the preservation of other anterior pituitary hormones, suggesting isolated ACTH deficiency. As it is rapidly improved by steroid replacement therapy, an early diagnosis and treatment make it possible to resume immunotherapy.

Immune Checkpoint Inhibitors and Associated Pituitary Dysfunctions: A Mini-Review.

Immune checkpoint inhibitors (ICIs) are widely used for various types of advanced cancers. Currently, three types of ICIs are clinically available, a monoclonal antibody targeting cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), and antibodies targeting the programmed cell death protein-1 (PD-1) and its ligand, programmed cell death ligand 1 (PD-L1). Although ICIs have improved the survival rates of several types of cancers, they induce immune-related adverse events (irAE) by their enhancement of immune responses. The pituitary gland is one of the common targets of irAE. In general, different clinical presentations of autoimmune pituitary dysfunctions are observed between anti-CTLA-4 and anti-PD-1/anti-PD-L1 antibodies, with anti-CTLA-4 inducing hypophysitis with multiple pituitary hormone deficiencies and targeting the PD-1/PD-L1 axis inducing isolated adrenocorticotropic hormone deficiency. This review describes the current understanding of the pathophysiology, clinical manifestation, and management of hypophysitis caused by ICIs.

Isolated adrenocorticotropic hormone deficiency associated with sintilimab therapy in a patient with advanced lung adenocarcinoma: a case report and literature review.

BACKGROUND: Several immune checkpoint inhibitors have been implemented for cancer treatment which have shown some degree of antitumor effcacy, while immune-related adverse events (irAEs) that affect multiple organ functions ensue which obviously should not be neglected. Though less common than other kinds of irAEs, Immune checkpoint inhibitors (ICIs) related Isolated ACTH deficiency (IAD) may cause long-term damage to pituitary-adrenal axis. Several case reports are available about IAD during anti-PD-1 therapy. We report the first case of immune checkpoint inhibitor-induced IAD following 3 month of sintilimab therapy. CASE PRESENTATION: A 66-year-old Chinese man was diagnosed with stage IIIB lung adenocarcinoma with involving ipsilateral intrapulmonary and hilar lymph node metastasis. After 3 months of combination therapy of nedaplatin, pemetrexed and sintilimab, the patient presented with general fatigue, nausea and vomiting. Laboratory investigation at admission revealed hyponatremia and hypokalemia. Further investigation revealed adrenocorticotropic hormone and cortisol levels were far below than normal limits. His other pituitary hormone levels were normal, except for mild elevation of follicle stimulating hormone and estradiol. Cranic magnetic resonance imaging showed a normal pituitary gland. Isolated adrenocorticotropic hormone deficiency was diagnosed, and corticosteroid replacement therapy was administered, leading to a significant improvement of his symptoms while ACTH level maintaining low level. CONCLUSIONS: Our patient developed isolated ACTH deficiency during combination cancer treatment with chemotherapy and sintilimab. Although isolated ACTH deficiency due to anti-PD-1 including sintilimab therapy is rare occurrence, it can often cause severe clinical symptoms. Its diagnosis basically relies on clinical symptoms and endocrinological examination. Unlike traditional hypophysitis diagnosed by cranial MRI, pituitary MRI of IAD due to anti-PD-1 often indicates normal pituitary gland implying that over-reliance on imaging findings is not recommended. Even if clinical symptoms have relieved after corticosteroid replacement therapy was commenced, low levels of ACTH or cortisol could maintain for a long period which highlights the need for long term corticosteroid therapy. The purpose of the current report was to provide increased awareness of early detection and therapy of IAD.

[Isolated ACTH deficiency clinically presented as stiff-person syndrome, successfully treated by hormonal replacement: a case report].

A 65-year-old man was admitted to our hospital with a 6-year history of painful muscle stiffness in his trunk and lower limbs, preventing him from walking. Stiff-person syndrome (SPS) was diagnosed because the patient had symptoms of painful muscle spasms elicited by tactile stimulation without joint contracture. Although SPS- related autoantibodies in the serum, including anti-glycine R, anti-amphiphysin, anti-glutamic acid decarboxylase (GAD), anti-dipeptidyl peptidase-like protein (DPPX) and anti-γ-aminobutyric acid-A (GABAA) R, were negative, the ACTH and cortisol levels were low. On the basis of additional loading tests for anterior pituitary function and ACTH, isolated ACTH deficiency (IAD) was diagnosed. Hormonal replacement therapy with hydrocortisone at 15 mg/day ameliorated the condition quickly, and the patient became asymptomatic after three months. Flexion contractures have been reported as musculoskeletal symptoms of IAD, but are not usually evident in patients with SPS. The present case illustrates that the painful muscle spasms elicited by tactile stimulation without joint contracture characteristic of SPS can also be symptoms of IAD.

Rare clinical problem - isolated ACTH deficiency associated with chronic alcohol abuse.

Isolated adrenocorticotropic hormone (ACTH) deficiency (IAD) is a rare pituitary disorder characterized by decreased secretion of ACTH, leading to cortisol deficiency, with normal secretion of other pituitary hormones. Diagnostics remains a challenge due to variable and nonspecific clinical presentation: weakness, weight loss, and low blood pressure. Hyponatremia and anemia are typical abnormalities in basic laboratory tests. Diagnostic procedures for IAD are based on results of low morning cortisol with low/normal ACTH concentrations, with flat response of these hormones in dynamic tests [with insulin/glucagon/corticotropin-releasing hormone (CRH)]. There is also no cortisol response to Synacthen during the standard (not extended) test duration. Several aetiologies lead to the development of IAD. The congenital form is typical of childhood onset. In adults, autoimmune aetiology prevails, including lymphocytic hypophysitis, and rarer - pituitary injury or other lesions in the gland. IAD has recently been demonstrated as a complication in patients receiving therapy with immune checkpoint inhibitors. Also, in the case of IAD, paraneoplastic autoimmune hypophysitis should be considered. Next, alcohol abuse has been reported to be a reason of IAD in single cases. Treatment with oral hydrocortisone usually causes significant improvement. As an example, we present 2 patients diagnosed with IAD. Both were older males, with history of alcohol abuse, long lasting hyponatremia, and weakness. Their clinical state normalized after receiving replacement therapy with hydrocortisone.

HLA analysis of immune checkpoint inhibitor-induced and idiopathic isolated ACTH deficiency.

PURPOSE: Isolated adrenocorticotropic hormone deficiency is a rare disease; however, since immune check point inhibitors (ICIs) have become widely used, many more cases have been reported. In this study, we compared the human leukocyte antigen (HLA) signatures between ICI-induced isolated adrenocorticotropic hormone deficiency (IAD) and idiopathic IAD (IIAD). DESIGN AND METHODS: Clinical features and HLA frequencies were compared among 13 patients with ICI-induced IAD, 8 patients with IIAD, and healthy controls. HLA frequencies of healthy controls were adopted from a HLA database of Japanese population. RESULTS: Age and body mass index were higher, while the rate of weight loss was lower, in patients with ICI-induced IAD than in those with IIAD. No HLA alleles had a significantly higher frequency in patients with ICI-induced IAD than in healthy controls, whereas the frequencies of HLA-DRB1*09:01, HLA-DQA1*03:02, and DQB1*03:03 were significantly higher in patients with IIAD than in healthy controls. CONCLUSIONS: ICI-induced IAD and IIAD were different in terms of HLA frequencies. There were no specific HLAs related to ICI-induced IAD, whereas several HLAs in strong linkage disequilibrium were associated with IIAD. This might suggest that the two diseases have different pathological mechanisms. HLAs unique to IIAD may be helpful in predicting its pathophysiology.

Paraneoplastic autoimmune hypophysitis: An emerging concept.

Pituitary autoimmunity is one of the principal causes of hypopituitarism. Additionally, hypophysitis is one of the immune-related adverse events associated with immunotherapy. Recent case-oriented research has revealed a novel type of autoimmune hypophysitis, anti-PIT-1 hypophysitis, related to isolated adrenocorticotropic hormone (ACTH) deficiency and immune checkpoint inhibitor-related hypophysitis, as a form of paraneoplastic syndrome. Under these conditions, the ectopic expression of pituitary antigens present in tumors evokes a breakdown of immune tolerance, resulting in the production of autoantibodies and autoreactive cytotoxic T cells that specifically harm pituitary cells. Consequently, an innovative clinical entity of paraneoplastic autoimmune hypophysitis has been purported. This novel concept and its underlying mechanisms provide clues for understanding the pathogenesis of autoimmune pituitary diseases and can be applied to other autoimmune diseases. This review discusses the etiology of paraneoplastic autoimmune hypophysitis and its future.

A novel TBX19 gene mutation in patients with isolated ACTH deficiency from distinct families with a common geographical origin.

Isolated ACTH deficiency (IAD) is a life-threatening condition, particularly in the neonatal period, while a main consequence of undiagnosed isolated ACTH deficiency in survivors is cognitive impairment. TBX19 is involved in the differentiation and proliferation of corticotropic cells and TBX19 mutations are responsible for more than 60% of neonatal cases of IAD. We describe a new variant of the main TBX19 transcript (NM 005149.3, c.840del (p.(Glu280Asp fs*27)), classified as pathogenic, whose pathogenicity is assumed to be due to nonsense mediated decay leading to non-expression of T-box transcription factor TBX19. Moreover we summarize the TBX19 mutations published as individual cases since our last large cohort. Interestingly, this pathogenic variant was identified in four patients from three apparently unrelated families. Two of these families were consanguineous, and after investigations all of three were discovered to have roots in the same mountainous region of northern Morocco, suggesting a founder effect. Early diagnosis, timely treatment (hydrocortisone therapy) and preventive education allowed normal development, growth and quality of life in all patients.

Case Report: A Variety of Immune-Related Adverse Events Triggered by Immune Checkpoint Inhibitors in a Subject With Malignant Melanoma: Destructive Thyroiditis, Aseptic Meningitis and Isolated ACTH Deficiency.

Recently, immune checkpoint inhibitors have been drawing much attention as cancer immunotherapy, but it has been shown that various immune-related adverse events (irAEs) are induced by immune checkpoint inhibitors in various organs, which has become one of the serious issues at present. A 58-year-old Japanese male with malignant melanoma was treated with nivolumab and/or ipilimumab. During the period of treatment, he suffered from various irAEs. Firstly, about 1 month after starting nivolumab monotherapy, destructive thyroiditis was induced, and so we started replacement therapy with levothyroxine. Secondly, about 1 month after starting nivolumab and ipilimumab combination therapy, aseptic meningitis was induced. We stopped both drugs and started steroid therapy with prednisolone. Finally, about 9 months after restarting nivolumab, isolated adrenocorticotropic hormone (ACTH) deficiency was induced, and so we started replacement therapy with hydrocortisone. Taken together, we should bear in mind the possibility of a variety of irAEs when we use immune checkpoint inhibitors.

Clinical Heterogeneity of Acquired Idiopathic Isolated Adrenocorticotropic Hormone Deficiency.

Objective: Heterogeneous clinical characteristics are observed in acquired isolated adrenocorticotropic hormone (ACTH) deficiency (IAD); however, its classification remains to be established because of its largely unknown pathophysiology. In IAD, anti-pituitary antibodies have been detected in some patients, although their significance remains unclear. Therefore, this study aimed to classify patients with IAD and to clarify the significance of anti-pituitary antibodies. Design and Methods: We analyzed 46 consecutive patients with IAD. Serum anti-pituitary antibodies were analyzed via immunofluorescence staining using a mouse pituitary tissue. Principal component and cluster analyses were performed to classify IAD patients based on clinical characteristics and autoantibodies. Results: Immunofluorescence analysis using the sera revealed that 58% of patients showed anti-corticotroph antibodies and 6% of patients showed anti-follicular stellate cell (FSC) antibodies. Principal component analysis demonstrated that three parameters could explain 70% of the patients. Hierarchical cluster analysis showed three clusters: Groups A and B comprised patients who were positive for anti-corticotroph antibodies, and plasma ACTH levels were extremely low. Groups A and B comprised middle-aged or elderly men and middle-aged women, respectively. Group C comprised patients who were positive for the anti-FSC antibody and elderly men; plasma ACTH levels were relatively high. Conclusions: Patients with IAD were classified into three groups based on clinical characteristics and autoantibodies. The presence of anti-corticotroph antibody suggested severe injury to corticotrophs. This new classification clearly demonstrated the heterogeneity in the pathogenesis of IAD.

Hypophysitis related to immune checkpoint inhibitors: An intriguing adverse event with many faces.

INTRODUCTION: The incorporation of immune checkpoint inhibitors in the oncologists' arsenal is a milestone in cancer therapeutics, though not being devoid of toxicities.Areas covered: The present review provides a comprehensive and up-to-date overview of the immune-related hypophysitis with focus on the elusive biological background, the wide spectrum of the epidemiological profile, the varying clinical aspects, and the diagnostic and therapeutic challenges.Expert opinion: Historically considered distinctive of anti-cytotoxic T-lymphocyte antigen 4 (CTLA-4) monoclonal antibodies (mAbs), the immune-related hypophysitis is increasingly correlated with the anti-programmed cell-death (PD) protein 1 (PD-1)/anti-PD ligand 1 (PD-L1) mAbs. The distinct phenotype of hypophysitis related to anti-PD1/anti-PD-L1 mAbs is highlighted with focus on the immune-related isolated adrenocorticotropic (ACTH) deficiency. The immune-related central diabetes insipidus is discussed as a rare aspect of anti-CTL-A4 mAbs-induced hypophysitis, recently related to anti-PD1/anti-PD-L1 mAbs as well. The present review builds on existing literature concerning immune-related hypophysitis underscoring the pending issues still to be addressed, including (i) pathogenesis; (ii) correlation with preexisting autoimmunity; (iii) predictive value; (iv) utility of high-dose glucocorticoids; and (v) establishment of evidence-based diagnostic and therapeutic protocols. Increased awareness and constant vigilance are advocated as cornerstone of a multidisciplinary approach to ensure optimal patients' care.

Check point inhibitors and autoimmunity: Why endocrinopathies and who is prone to?

Immunotherapy has transformed the treatment of cancer by restoring the power of the immune system against tumor cells. Disruption of the innate immune inhibition has introduced a large and growing spectrum of immune-related adverse effects (irAEs), with the endocrine system being a prominent target to autoimmune damage. What makes the endocrine system a prominent target when facing an unleashed immune system? Why are the endocrine irAEs mostly irreversible and unresponsive to glucocorticoid therapy? Is it possible to identify those prone to develop irAEs? The presents review describes the unique characteristics of the endocrine system and its crosstalk with the immune system. In a broader perspective, the iatrogenic side effects of immunotherapy provide a unique opportunity to explore the genetic, humoral and cytotoxic immune confounders.

Autoimmune Pituitary Disease: New Concepts With Clinical Implications.

Some endocrine disorders, including hypophysitis and isolated adrenocorticotropic hormone (ACTH) deficiency, are caused by an autoimmune response to endocrine organs. Although the pathogenesis of some autoimmune endocrine diseases has been elucidated, it remains obscure for most. Anti-PIT-1 hypophysitis (anti-PIT-1 antibody syndrome) is a newly described pituitary autoimmune disease characterized by acquired and specific growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone (TSH) deficiencies. This disorder is associated with a thymoma or neoplasm that ectopically expresses pituitary-specific transcription factor 1 (PIT-1) protein. Circulating anti-PIT-1 antibody is a disease marker, and PIT-1-reactive cytotoxic T cells (CTLs) play a pivotal role in disease development. In addition, isolated ACTH deficiency appears to be caused by autoimmunity to corticotrophs; however, the pathogenesis remains unclear. A recently described case of isolated ACTH deficiency with large cell neuroendocrine carcinoma (LCNEC) showed ectopically expressed proopiomelanocortin (POMC), and circulating anti-POMC antibody and POMC-reactive CTLs were also detected. As CTL infiltrations around corticotrophs were also observed, isolated ACTH deficiency may be associated at least in part with a paraneoplastic syndrome. Although several underlying mechanisms for pituitary autoimmunity have been proposed, these observations highlight the importance of paraneoplastic syndrome as a cause of pituitary autoimmune disease. In this review, we focus on the pathophysiology and connection of anti-PIT-1 hypophysitis and isolated ACTH deficiency and discuss the state-of-art knowledge for understanding pituitary autoimmunity.

Fulminant type 1 diabetes associated with Isolated ACTH deficiency induced by anti-programmed cell death 1 antibody-insight into the pathogenesis of autoimmune endocrinopathy.

Therapeutic blocking antibodies against programmed death 1 (PD1) and cytotoxic T-lymphocyte antigen 4 (CTLA4) are applied for advanced cancer therapy, but induce a wide range of immune-related adverse events. In our recent case of a 52-year-old female doctor suffering from breast cancer having metastasized to the lung and liver, it was decided to use nivolumab to prevent the disease progressing after excisional surgeries and multiple chemotherapies. One month after completing the nivolumab course, fatigue, hypoglycemia and hypotension developed and isolated ACTH deficiency (IAD) was diagnosed. A further month later, under steroid supplementation, hyperglycemia emerged alongside thirst and polydipsia, prompting a diagnosis of fulminant type 1 diabetes (FT1D). Her susceptibility to type 1 diabetes was examined by HLA haplotype and CTLA4 gene polymorphism analyses. Polymorphisms CT60G>A and +49G>A in CTLA4 both generated a GG genotype. Our patient manifested one of the rarest combinations of autoimmune disease induced by nivolumab. Whereas the HLA haplotype was unsusceptible to autoimmune type 1 diabetes, polymorphisms of CTLA4, the antibody of which frequently causes hypophysitis, were susceptible to FT1D. Peripheral modulation of activated T cells, mainly by PD-1 antibodies, induced FT1D associated with IAD in patients with CTLA4 polymorphism. This case reveals hints of the T-cell etiology in T1D and evidence of CTLA4 involvement in IAD.

A case of nivolumab-induced isolated adrenocorticotropic hormone (ACTH) deficiency.

One of the novel PD-1 antibodies/immune checkpoint inhibitors, nivolumab is reported to be associated with a wide range of immune-related adverse events (irAEs). We hereby report a case of isolated adrenocorticotropic hormone (ACTH) deficiency developing in a patient with squamous cell lung cancer (SCC) during nivolumab therapy. CASE: A 79-year-old man with SCC was started on nivolumab therapy as a fifth-line treatment after 4 lines of cytotoxic anticancer therapy. After 20 courses of nivolumab therapy, he had nausea, appetite loss, and difficulty walking. A close laboratory examination led to the diagnosis of isolated ACTH deficiency in this patient. Hydrocortisone replacement therapy led to amelioration of his symptoms and allowed him to continue with nivolumab therapy. The present case of isolated ACTH deficiency was characterized by a slowly progressive decline in the serum sodium level, which became manifest well before appearance of any clinical symptoms, suggesting that the serum sodium level may be used to predict progression to isolated ACTH deficiency.Thus, not only serum sodium levels need to be monitored in patients suspected of having isolated ACTH deficiency, but ACTH and cortisol levels need to be monitored in those exhibiting a decline in serum sodium levels. Again, nivolumab-induced isolated ACTH deficiency needs to be appropriately diagnosed and treated to ensure that patients continue with, and maximize survival benefit from, nivolumab therapy.