Antidiuretic hormone deficiency secondary to inactive hydrocephalus: a case report.

BACKGROUND: Diabetes insipidus is a syndrome characterized by polyuria, which is almost always associated with polydipsia. The most frequent cause is central diabetes insipidus, which is the result of an inadequate secretion of the antidiuretic hormone, and diagnosis involves differentiating it from other causes of polyuria and polydipsia. CASE PRESENTATION: Here, we present a clinical case of a previously healthy 13-year-old Nepali boy, who, in December 2022, was found to have intense polydipsia accompanied by polyuria. He had bilateral lower limb weakness at the time of presentation. Biochemical evaluation demonstrated raised serum sodium (181 mEq/L), serum creatinine (78 µmol/L), and serum uric acid (560 µmol/L) with suppressed serum potassium (2.7 mEq/L), which was the major concern to the clinicians. Further laboratory workup revealed an increased serum osmolarity (393.6 mOsm/kg) with reduced urine osmolarity (222.7 mOsm/kg). On contrast magnetic resonance imaging of the brain, a thick-walled third ventricular cyst with bilateral foramen obstruction, thin membrane-like structure at top of aqueduct of Sylvius with gross obstructive hydrocephalus (inactive), and compressed and thinned pituitary gland with no bright spot was observed. The laboratory findings, radiological findings, and case presentation provided the provisional diagnosis of diabetes insipidus due to hydrocephalus and third ventricular cyst. CONCLUSIONS: Central diabetes insipidus due to hydrocephalus, though rare, can have serious complications including the predilection to develop a deficit of other pituitary hormones. Thus, even if hydrocephalus is dormant with normal intracranial pressure, it must be addressed during investigations of central diabetes insipidus.

Endocrine features of Langerhans cell histiocytosis in paediatric patients: A 30-year review.

Langerhans cell histiocytosis (LCH) is a rare proliferative disorder characterised as an inflammatory myeloid neoplasia. Endocrine manifestations of LCH, particularly central diabetes insipidus (CDI), have been described from the 1940s, through case studies and small cohort analyses. There are limited Australian paediatric data described in recent literature. AIM: To document the incidence of endocrine features in paediatric patients with LCH, treated at a tertiary paediatric centre in Victoria, Australia. METHODS: Retrospective chart review of electronic medical records and oncology database of patients with LCH managed at a tertiary paediatric centre. Patients were excluded if a biopsy did not suggest LCH or if records were incomplete. RESULTS: One hundred seventy-one patients were identified and 141 records of patients diagnosed with LCH over the last 30 years were assessed for endocrinopathies, from diagnosis to last documented follow-up. Mean age at diagnosis was 5 years 8 months. Of these, 15% (n = 21) had CDI, 7% had growth hormone deficiency (GHD) (n = 10) and 8% (n = 11) had more than one endocrinopathy noted during follow-up. Forty percent (n = 57) were pre-pubertal at the time of audit or upon discharge from tertiary services. CONCLUSIONS: Ongoing pituitary assessment, in addition to CDI, is required to detect evolving deficiencies of GHD and gonadotropins as these can be subtle, late or missed. Close follow-up of growth and progression through puberty, even if discharged from tertiary care, is essential.

Absence of anti-rabphilin-3A antibodies in children and young adults with idiopathic central diabetes insipidus: a potential clue to elucidating a tumor etiology.

BACKGROUND: Central diabetes insipidus (CDI) is a rare condition caused by various underlying diseases, including neoplasms, autoimmune diseases, and infiltrative diseases. Differentiating between CDI etiologies is difficult. What has initially been classified as "idiopathic" central diabetes insipidus might in fact underlie various pathogenic mechanisms that are less understood to date and/or are not obvious at initial presentation. Therefore, even if idiopathic CDI is diagnosed at the time of onset, it is common for tumors such as germinoma to develop during surveillance. Crucially, a delayed diagnosis of germinoma may be associated with a worse prognosis. Recently, the presence of anti-rabphilin-3A antibodies has been found to be a highly sensitive and specific marker of lymphocytic infundibuloneurohypophysitis, an autoimmune-mediated CDI. CASE PRESENTATION: We herein present two cases, namely, a 13-year-old boy (patient 1) and a 19-year-old young man (patient 2) who were diagnosed with idiopathic CDI. In both patients, panhypopituitarism developed. Magnetic resonance imaging revealed pituitary stalk thickening and pituitary swelling approximately 1 1/2 years after the onset of CDI. Western blotting did not reveal the presence of anti-rabphilin-3A antibodies in serum in either patient, suggesting that autoimmune mechanisms might not be involved. Both patients were subsequently diagnosed with germinoma on pathological examination. They received chemotherapy, followed by radiation therapy. Notably, testosterone and insulin-like growth factor-1 levels normalized, and libido and beard growth recovered after chemoradiotherapy in patient 2. CONCLUSION: Our data suggest that the absence of anti-rabphilin-3A antibodies in young patients clinically diagnosed with idiopathic CDI may increase the probability of the development of non-lymphocytic lesions, including germinoma. We thus recommend a more attentive approach at the onset of these diseases.

AVP deficiency (central diabetes insipidus) following immunization with anti-COVID-19 BNT162b2 Comirnaty vaccine in adolescents: A case report.

Introduction: The coronavirus disease 19 (COVID-19) pandemic has prompted the development of new vaccines to reduce the morbidity and mortality associated with this disease. Recognition and report of potential adverse effects of these novel vaccines (especially the urgent and life-threatening ones) is therefore essential. Case presentation: A 16-year-old boy presented to the Paediatric Emergency Department with polyuria, polydipsia and weight loss over the last four months. His past medical history was unremarkable. Onset of symptoms was referred to be few days after first dose of anti-COVID-19 BNT162b2 Comirnaty vaccine and then worsened after the second dose. The physical exam was normal, without neurological abnormalities. Auxological parameters were within normal limits. Daily fluid balance monitoring confirmed polyuria and polydipsia. Biochemistry laboratory analysis and urine culture were normal. Serum osmolality was 297 mOsm/Kg H2O (285-305), whereas urine osmolality was 80 mOsm/Kg H2O (100-1100), suggesting diabetes insipidus. Anterior pituitary function was preserved. Since parents refused to give consent to water deprivation test, treatment with Desmopressin was administered and confirmed ex juvantibus diagnosis of AVP deficiency (or central diabetes insipidus). Brain MRI revealed pituitary stalk thickening (4 mm) with contrast enhancement, and loss of posterior pituitary bright spot on T1 weighted imaging. Those signs were consistent with neuroinfundibulohypophysitis. Immunoglobulin levels were normal. Low doses of oral Desmopressin were sufficient to control patient's symptoms, normalizing serum and urinary osmolality values and daily fluid balance at discharge. Brain MRI after 2 months showed stable thicken pituitary stalk and still undetectable posterior pituitary. Due to persistence of polyuria and polydipsia, therapy with Desmopressin was adjusted by increasing dosage and number of daily administrations. Clinical and neuroradiological follow-up is still ongoing. Conclusion: Hypophysitis is a rare disorder characterized by lymphocytic, granulomatous, plasmacytic, or xanthomatous infiltration of the pituitary gland and stalk. Common manifestations are headache, hypopituitarism, and diabetes insipidus. To date, only time correlation between SARS-CoV-2 infection and development of hypophysitis and subsequent hypopituitarism has been reported. Further studies will be needed to deepen a possible causal link between anti-COVID-19 vaccine and AVP deficiency.

Central Diabetes Insipidus in the Background of Lithium Use: Consider Central Causes Despite Nephrogenic as the Most Common.

BACKGROUND Nephrogenic diabetes insipidus is a well-known adverse effect of lithium use. Albeit rare, there have also been documented cases of central diabetes insipidus (CDI) associated with lithium use. CASE REPORT A 31-year-old woman with a past medical history of bipolar disorder, managed with lithium 300 mg by mouth every day for 3 years, was assessed for a 1-year history of polyuria with accompanying polydipsia. During her initial hospital stay, her estimated urine output was more than 4 L per day. Initial labs showed elevated serum sodium (149 mmol/L; reference range 135-145), elevated serum osmolality (304 mOsm/kg; reference range 275-295), urine osmolality of 99 mOsm/kg (reference range 50-1200), and urine specific gravity (1.005; reference range 1.005-1.030). Lithium was at a subtherapeutic level of 0.05 mEq/L (reference range 0.6-1.2). Magnetic resonance imaging of the brain revealed no abnormalities of the pituitary gland. Two different occasions of desmopressin administration resulted in >50% increase in urine osmolality, confirming the diagnosis of CDI. Common causes of CDI, including trauma, tumors, and familial CDI, were ruled out and chronic lithium use was determined as the most probable cause for the patient's CDI. CONCLUSIONS CDI in the background of chronic lithium use is rarely reported. We present this case to consider CDI as a differential diagnosis when evaluating polyuria and hypernatremia in patients with long-term lithium use. These presentations warrant the consideration of both types of diabetes insipidus in the differential diagnoses.

Central diabetes insipidus with anti-rabphilin-3A antibody positivity causing hypovolemic shock after resection of tumorous lesions in the pelvic cavity.

A 36-year-old female was pointed out to have liver enzyme elevation by routine health checkup. Subsequent contrast-enhanced CT scan identified gigantic uterine fibroids and retroperitoneal tumor. She was referred to the gynecologist at JA Toride Medical Center and planned to undergo a uterus enucleation and biopsy of the retroperitoneal tumor. The surgery was conducted without any troubles. After the surgery, the patient presented polyuria with urine volume 10-20 L a day and developed hypovolemic shock. Laboratory test revealed hypotonic urine and hypernatremia. Arginine vasopressin (AVP) loading test suggested shortage of endogenous vasopressin. Since the subcutaneous administration of AVP was not sufficient to control the urine volume, continuous intravenous infusion of AVP was initiated. After achieving hemodynamic stability, the treatment was switched to oral desmopressin. MRI finding indicated attenuation of high signal in posterior pituitary in T1 weighted image while neither enlargement of pituitary nor thickening of pituitary stalk was indicated by enhanced MRI. Hypertonic salt solution test indicated no responsive elevation of AVP, confirming the diagnosis of central diabetes insipidus (CDI). Her anterior pituitary function was preserved. Only anti-rabphilin-3A antibody was found positive in the serum of the patient, while other secondary causes for CDI were denied serologically and radiologically. Hence, lymphocytic infundibuloneurohypophysitis　(LINH) was suspected as the final diagnosis. Hormonal replacement therapy by nasal desmopressin was continued and the patient managed to control her urine volume. In cases of CDI considered idiopathic with conventional examinations, anti-rabphilin-3A antibody may be a clue for determining the cause as LINH.

Machine learning-based algorithm as an innovative approach for the differentiation between diabetes insipidus and primary polydipsia in clinical practice.

Objective: Differentiation between central diabetes insipidus (cDI) and primary polydipsia (PP) remains challenging in clinical practice. Although the hypertonic saline infusion test led to high diagnostic accuracy, it is a laborious test requiring close monitoring of plasma sodium levels. As such, we leverage machine learning (ML) to facilitate differential diagnosis of cDI. Design: We analyzed data of 59 patients with cDI and 81 patients with PP from a prospective multicenter study evaluating the hypertonic saline test as new test approach to diagnose cDI. Our primary outcome was the diagnostic accuracy of the ML-based algorithm in differentiating cDI from PP patients. Methods: The data set used included 56 clinical, biochemical, and radiological covariates. We identified a set of five covariates which were crucial for differentiating cDI from PP patients utilizing standard ML methods. We developed ML-based algorithms on the data and validated them with an unseen test data set. Results: Urine osmolality, plasma sodium and glucose, known transsphenoidal surgery, or anterior pituitary deficiencies were selected as input parameters for the basic ML-based algorithm. Testing it on an unseen test data set resulted in a high area under the curve (AUC) score of 0.87. A further improvement of the ML-based algorithm was reached with the addition of MRI characteristics and the results of the hypertonic saline infusion test (AUC: 0.93 and 0.98, respectively). Conclusion: The developed ML-based algorithm facilitated differentiation between cDI and PP patients with high accuracy even if only clinical information and laboratory data were available, thereby possibly avoiding cumbersome clinical tests in the future.

Idiopathic central diabetes insipidus in a large cohort of patients: the hypopituitarism ENEA rare observational (HEROS) study.

Central Diabetes Insipidus (CDI) is mainly associated with structural pathologies of the hypothalamic-pituitary area. Etiologies underlying CDI are identified in most patients, however idiopathic CDI is reported in 13-17% of cases after excluding other etiologies. The Hypopituitarism ENEA Rare Observational Study (HEROS study) retrospectively collected data of patients with idiopathic CDI from 14 pituitary centers in 9 countries. The cohort included 92 patients (59 females 64%), mean age at diagnosis was 35.4 ± 20.7 years, and a mean follow up of 19.1 ± 13.5 years following CDI diagnosis. In 6 women, diagnosis was related to pregnancy. Of 83 patients with available data on pituitary imaging, 40(48%) had normal sellar imaging, and 43(52%) had pathology of the posterior pituitary or the stalk, including loss of the bright spot, posterior pituitary atrophy or stalk enlargement. Anterior pituitary hormone deficiencies at presentation included hypogonadism in 6 (6.5%) patients (5 females), and hypocortisolism in one; during follow-up new anterior pituitary deficiencies developed in 6 patients. Replacement treatment with desmopressin was given to all patients except one, usually with an oral preparation. During follow up, no underlying disease causing CDI was identified in any patient. Patients with idiopathic CDI following investigation at baseline are stable with no specific etiology depicted during long-term follow-up.

[Permanent central diabetes insipidus after traumatic brain injury. Case report and literature review]. / Razvitie postoyannogo tsentral'nogo nesakharnogo diabeta posle travmaticheskogo povrezhdeniya golovnogo mozga. Klinicheskii sluchai i obzor literatury.

The authors report permanent central diabetes insipidus (CDI) in a patient after severe traumatic brain injury (TBI) in traffic accident. A 16-year-old boy entered to a medical facility in coma (GCS score 6) with the following diagnosis: acute TBI, severe cerebral contusion, subarachnoid hemorrhage, depressed comminuted cranial vault fracture, basilar skull fracture, visceral contusion. CDI was diagnosed in 3 days after injury considering polyuria and hypernatremia (155 mmol/l). Desmopressin therapy was initiated through a feeding tube. Thirst appeared when a patient came out of the coma after 21 days despite ongoing desmopressin therapy. Considering persistent thirst and polyuria, we continued desmopressin therapy in a spray form. Under this therapy, polyuria reduced to 3-3.5 liters per a day. Symptoms of CDI persisted in long-term period (2 years after TBI) while function of adenohypophysis was intact. This case demonstrates a rare development of permanent diabetes insipidus after TBI. CDI manifested only as polyuria and hypernatremia in coma. Thirst joined after recovery of consciousness. Probable causes of CDI were damage to neurohypophysis and partially injury of pituitary stalk because of extended basilar skull fracture and/or irreversible secondary lesion of hypothalamus following diffuse axonal damage after TBI.

Secondary autoimmune hypothalamitis with severe memory impairment 7 years after the onset of diabetes insipidus due to lymphocytic hypophysitis: a case report.

BACKGROUND: Autoimmune hypothalamitis is a very rare neuroendocrine disorder that causes central diabetes insipidus, headache, visual impairment, and sometimes cognitive impairment. Autoimmune hypothalamitis may occur in association with autoimmune hypophysitis, including lymphocytic hypophysitis, or in isolation. It is not known whether autoimmune hypothalamitis and autoimmune hypophysitis are consecutive diseases. CASE PRESENTATION: A 52-year-old woman developed autoimmune hypothalamitis 7 years after developing central diabetes insipidus due to lymphocytic hypophysitis, resulting in severe memory impairment. High-dose intravenous methylprednisolone therapy improved her cognitive function and decreased the size of the lesion. CONCLUSION: This case presented a unique clinical course, with a long period of time between the onset of autoimmune hypopituitaritis and the development of autoimmune hypothalamitis.

[Hypernatremia and polyuria in a female patient with an initial diagnosis of secondary acute myeloid leukemia]. / Hypernatriämie und Polyurie bei einer Patientin mit Erstdiagnose einer sekundären akuten myeloischen Leukämie.

A 66-year-old female patient with the initial diagnosis of acute myeloid leukemia is reported. Paraneoplastic syndrome manifested as hypernatremia due to central diabetes insipidus (CDI), which could be controlled with the administration of desmopressin. After initiation of the induction therapy, the required desmopressin administration could be reduced and terminated. In the further course, the early increasing polyuria and hypernatremia indicated the primary refractory acute myeloid leukemia.

Evaluation of the etiological and clinical characteristics of pediatric central diabetes insipidus.

OBJECTIVES: Central diabetes insipidus (CDI) is a rare but important disease of varying etiology that poses challenges in diagnosis and follow-up. Identifying diagnostic difficulties in patients with CDI will help ensure an optimal approach to their management and follow-up. This study aimed to characterize the clinical and etiological characteristics of CDI in pediatric patients. METHODS: We analyzed the admission and follow-up data of CDI patients aged 0-18 years who were followed in our center between 2010 and 2019. RESULTS: The study included 56 patients with a mean age at diagnosis of 7.92 ± 5.11 years and symptom duration of 8.65 ± 21.3 months. The patients were grouped by etiology into those with organic causes, such as structural anomalies, tumors, and trauma (group 1, n=41) and other causes (group 2, n=15). The prevalence of idiopathic CDI was 16%. At least one pituitary hormone deficiency was detected in 60.7%, the most common being thyroid stimulating hormone deficiency. Patients in group 1 had a higher mean age at diagnosis, shorter symptom duration, and higher frequency of other pituitary hormone deficiencies compared to group 2. Additionally, germinoma was detected 1 year subsequent to normal MRI findings at diagnosis and another patient was diagnosed with Langerhans cell histiocytosis (LCH) 5 years after diagnosis. All patients responded well to replacement therapies, but two patients with germinoma died during follow-up. CONCLUSIONS: In the pediatric age group, intracranial organic pathologies are an important etiology of CDI, and despite a short symptomatic period, determining the cause may be challenging and prolonged. Patients presenting at a young age with a long history of symptoms and no other pituitary hormone deficiency are unlikely to have organic CDI. However, organic causes such as LCH should be evaluated at all ages. Patients with idiopathic disease are candidates for further etiological studies, and repeated cranial imaging is important during follow-up.

Diagnosis and Management of Central Diabetes Insipidus in Adults.

Central diabetes insipidus (CDI) is a clinical syndrome which results from loss or impaired function of vasopressinergic neurons in the hypothalamus/posterior pituitary, resulting in impaired synthesis and/or secretion of arginine vasopressin (AVP). AVP deficiency leads to the inability to concentrate urine and excessive renal water losses, resulting in a clinical syndrome of hypotonic polyuria with compensatory thirst. CDI is caused by diverse etiologies, although it typically develops due to neoplastic, traumatic, or autoimmune destruction of AVP-synthesizing/secreting neurons. This review focuses on the diagnosis and management of CDI, providing insights into the physiological disturbances underpinning the syndrome. Recent developments in diagnostic techniques, particularly the development of the copeptin assay, have improved accuracy and acceptability of the diagnostic approach to the hypotonic polyuria syndrome. We discuss the management of CDI with particular emphasis on management of fluid intake and pharmacological replacement of AVP. Specific clinical syndromes such as adipsic diabetes insipidus and diabetes insipidus in pregnancy as well as management of the perioperative patient with diabetes insipidus are also discussed.

Central Diabetes Insipidus Due to IgG4-related Hypophysitis That Required over One Year to Reach the Final Diagnosis Due to Symptoms Being Masked by Sialadenitis.

Pituitary inflammation due to IgG4-related disease is a rare condition and is sometimes accompanied by central diabetes insipidus. Central diabetes insipidus produces a strong thirst sensation, which may be difficult to distinguish when complicated by salivary insufficiency. A 45-year-old man was admitted to our department for a thorough examination of his thirst and polyuria. He had suddenly developed these symptoms more than one year earlier and visited an oral surgeon. Swelling of the left submandibular gland, right parotid gland, and cervical lymph nodes had been observed. Since his IgG4 level was relatively high at 792 mg/dL and a lip biopsy showed high plasmacytoid infiltration around the gland ducts, he had been diagnosed with IgG4-related disease. He had started taking 0.4 mg/kg/day of prednisolone, and his chief complaint temporarily improved. However, since the symptom recurred, he was referred to our institution. After admission, to examine the cause of his thirst and polyuria, we performed a water restriction test, vasopressin loading test, hypertonic saline loading test and pituitary magnetic resonance imaging. Based on the findings, we diagnosed him with central diabetes insipidus due to IgG4-related hypophysitis. We increased the dose of prednisolone to 0.6 mg/kg/day and started 10 µg/day of intranasal desmopressin. His symptoms were subsequently alleviated, and his serum IgG4 level finally normalized. We should remember that IgG4-related disease can be accompanied by hypophysitis and that central diabetes insipidus is brought about by IgG4-related hypophysitis. This case report should remind physicians of the fact that pituitary inflammation due to IgG4-related disease is very rare and can be masked by symptoms due to salivary gland inflammation, which can lead to pitfalls in the diagnosis in clinical practice.

[Central diabetes insipidus]. / Diabète insipide central.

"Central diabetes insipidus Diabetes insipidus may remain undetected for a long time, the ionogram remaining normal as long as polydipsia compensates for diuresis. In the first place, and by argument of frequency, polyuria should rule out diabetes. Diabetes insipidus is evoked in the presence of an incapacitating polyuro polydipsic syndrome, especially at night. Pituitary MRI eliminate a tumoral or infiltrative cause and confirm a central cause by the disappearance of the physiological t1 hypersignal in the post-pituitary gland. A water restriction test should only be performed in a hospital setting under close supervision. Lifetime hormone replacement therapy is appropriate in situations of pregnancy, risk of dehydration, and signs of overdose must be known by the patient, who must be educated about his or her disease."

"Diabète insipide central Le diabète insipide peut rester longtemps inaperçu, l'ionogramme restant normal tant que la polydipsie compense la diurèse. En premier lieu, et par argument de fréquence, une polyurie doit faire éliminer un diabète. Le diabète insipide est évoqué devant un syndrome polyuro-polydipsique invalidant, notamment nocturne. L'IRM hypophysaire a alors deux objectifs : éliminer une cause tumorale ou infiltrative et affirmer une cause centrale par la disparition de l'hypersignal t1 physiologique au niveau de la post-hypophyse. Un test de restriction hydrique ne doit être réalisé qu'en milieu hospitalier sous surveillance rapprochée. Le traitement hormonal substitutif à vie est adapté dans les situations de grossesse, de risque de déshydratation et les signes de surdosage doivent être connus du patient, éduqué à sa maladie."

Studies on anti-rabphilin-3A antibodies in 15 consecutive patients presenting with central diabetes insipidus at a single referral center.

Central diabetes insipidus (CDI) is a rare condition caused by various underlying diseases including inflammatory and autoimmune diseases, and neoplasms. Obtaining an accurate definitive diagnosis of the underlying cause of CDI is difficult. Recently, anti-rabphilin-3A antibodies were demonstrated to be a highly sensitive and specific marker of lymphocytic infundibuloneurohypophysitis (LINH). Here, we report a detailed case series, and evaluated the significance of anti-rabphilin-3A antibodies in differentiating the etiologies of CDI. A prospective analysis was conducted in 15 consecutive patients with CDI from 2013 to 2020 at a single referral center. Anti-rabphilin-3A antibodies were measured and the relationship between antibody positivity and the clinical/histopathological diagnoses was evaluated. Among 15 CDI patients, the positive anti-rabphilin-3A antibodies were found in 4 of 5 LINH cases, 3 of 4 lymphocytic panhypophysitis (LPH) cases, one of 2 sarcoidosis cases, and one intracranial germinoma case, respectively. Two Rathke cleft cyst cases and one craniopharyngioma case were negative. This is the first report of anti-rabphilin-3A antibodies positivity in CDI patients with biopsy-proven LPH. Measurement of anti-rabphilin-3A antibodies may be valuable for differentiating CDI etiologies.

A 7-year-old boy with central diabetes insipidus presenting with thickened pituitary stalk and anti-rabphilin-3A antibody positivity.

OBJECTIVES: A highly invasive pathological diagnosis is necessary to differentiate central diabetes insipidus (CDI) with a thickened pituitary stalk. Lymphocytic infundibulo-hypophysitis (LIH) due to autoimmune involvement of the pituitary stalk is a differentiating disease, and anti-rabphilin-3A antibody (Rab3A-Ab) positivity was recently reported. CASE PRESENTATION: A 7-year-old boy was diagnosed with CDI after having polyuria for two months. He showed growth hormone deficiency with reduced growth rate. Brain magnetic resonance imaging (MRI) revealed a thickened pituitary stalk. The placental alkaline phosphatase level of the cerebrospinal fluid, tumor marker for germ cell tumors, was below the level of sensitivity. No skin or bone findings suggestive of Langerhans cell histiocytosis were detected. Eight months after CDI onset, Rab3A-Ab was positive, and MRI showed shrinking of the thickened pituitary stalk, leading to the diagnosis with LIH. CONCLUSIONS: Rab3A-Ab is a useful adjunctive diagnostic tool for childhood-onset LIH.

Lymphocytic panhypophysitis and anti-rabphilin-3A antibody with pulmonary sarcoidosis.

PURPOSE: To explore the clinical significance of anti-rabphillin-3A antibody for the differential diagnosis of lymphocytic panhypophysitis. METHODS AND RESULTS: A 58-year-old Japanese man developed uveitis of unknown cause in 2017. In 2019, he became aware of polyuria. In August 2020, he noticed transient diplopia and was diagnosed with right abducens nerve palsy. At the same time, he complained of fatigue and loss of appetite. Head magnetic resonance imaging demonstrated enlargement of the pituitary stalk and pituitary gland, corresponding to hypophysitis. Hormone stimulation tests showed blunted responses with respect to all anterior pituitary hormones. Central diabetes insipidus was diagnosed on the basis of a hypertonic saline loading test. Taking these findings together, a diagnosis of panhypopituitarism was made. Computed tomography showed enlargement of hilar lymph nodes. Biopsies of the hilar lymph nodes revealed non-caseating epithelioid cell granulomas that were consistent with sarcoidosis. Biopsy of the anterior pituitary revealed mild lymphocyte infiltration in the absence of IgG4-positive cells, non-caseating granulomas, or neoplasia. Western blotting revealed the presence of anti-rabphilin-3A antibody, supporting a diagnosis of lymphocytic panhypophysitis. Because the patient had no visual impairment or severe uveitis, we continued physiological hormone replacement therapy and topical steroid therapy for the uveitis. CONCLUSION: To the best of our knowledge, this is the first case of anti-rabphilin 3A antibody positive lymphocytic panhypophysitis comorbid with sarcoidosis, diagnosed by both pituitary and hilar lymph node biopsy. The utility of anti-rabphilin-3A antibody for the differential diagnosis of hypophysitis like this case should be clarified with further case studies.

Approach to the Pediatric Patient: Central Diabetes Insipidus.

Central diabetes insipidus (CDI) is a complex disorder in which large volumes of dilute urine are excreted due to arginine-vasopressin deficiency, and it is caused by a variety of disorders affecting the hypothalamic-posterior pituitary network. The differential diagnosis is challenging and requires a detailed medical history, physical examination, biochemical approach, imaging studies, and, in some cases, histological confirmation. Magnetic resonance imaging is the gold standard method for evaluating congenital or acquired cerebral and pituitary stalk lesions. Pituitary stalk size at presentation could be normal, but it may change over time, depending on the underlying condition, while other brain areas or organs may become involved during follow-up. Early diagnosis and treatment are crucial to avoid central nervous system damage and germ cell tumor dissemination and to minimize complications of multiple pituitary hormone defects. We provide a practical update on the diagnosis and management of patients with CDI and highlight several pitfalls that may complicate the differential diagnosis of conditions presenting with polyuria and polydipsia. The need for a careful and close follow-up of patients with apparently idiopathic CDI is particularly emphasized because the underlying condition may be recognized over time. The clinical scenario that we outline at the beginning of this article represents the basis for the discussion about how the etiological diagnosis of CDI can be overlooked and demonstrates how a water intake and urine output improvement can be a sign of progressive damage of both hypothalamus and anterior pituitary gland with associated pituitary hormonal deficiencies.

Central Diabetes Insipidus after Syndrome of Inappropriate Antidiuretic Hormone Secretion with Severe Hyponatremia in a Patient with Rathke's Cleft Cyst.

A 49-year-old man developed severe hyponatremia associated with transient headache and was diagnosed with syndrome of inappropriate antidiuretic hormone secretion (SIADH). Fluid restriction and sodium supplementation corrected the hyponatremia. However, several days later, the patient exhibited hypernatremia with thirst and polyuria. A detailed examination indicated central diabetes insipidus (CDI) with an intrasellar cystic lesion indicative of Rathke's cleft cyst (RCC). A case of RCC exhibiting headache, hyponatremia, and subsequent hypernatremia has been reported. Our case shows that CDI may appear after SIADH in patients with RCC, especially in those with serum sodium levels that unexpectedly increase rapidly beyond the reference range.