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.

Persistent hypernatremia secondary to adipsic central diabetes insipidus in a patient with herpes-induced meningoencephalitis and COVID-19 infection: a case report.

Central diabetes insipidus (CDI) typically manifests as a polyuria-polydipsia syndrome, in which normonatremia is generally maintained through the polydipsia. A 53-year-old woman presented with diabetic ketosis and hyperosmolar hyperglycemic syndrome. Her medical history included herpes meningoencephalitis, which was associated with confusion and amnesia. On physical examination, she was apyretic, confused, and had signs of extracellular dehydration. Her capillary glucose concentration was high and her urine was positive for ketones. Laboratory investigations revealed severe hyperglycemia, hypernatremia (plasma hyperosmolarity of 393.6 mOsm/L), and mild acute renal failure. In addition, she had a paucisymptomatic COVID-19 infection. Intravenous rehydration with isotonic saline solution and insulin therapy were effective at controlling the ketosis and ameliorating the hyperglycemia, but failed to normalize the hypernatremia and hyperosmolarity. She was not thirsty and had a urine output of 1 L/day, with urinary hypotonicity. Desmopressin administration reduced the hypernatremia and hyperosmolarity to within their normal ranges, and the patient's urinary osmolarity increased to 743 mOsm/L. Therefore, adipsic CDI was diagnosed. Endocrine investigations revealed isolated central hypothyroidism. The results of pituitary magnetic resonance imaging were normal. Thus, patients with impaired thirst may have an atypical presentation of CDI. In addition, the diagnosis of adipsic CDI is particularly challenging.

Spontaneous remission and relapse of diabetes mellitus in a male dog.

An 8-year-old male neutered Miniature Schnauzer was diagnosed with diabetes mellitus based on fasting hyperglycemia and glucosuria after a 2-week history of polydipsia and periuria, in line with the Agreeing Language in Veterinary Endocrinology consensus definition. Treatment of insulin and dietary management was initiated. The insulin dose was gradually reduced and eventually discontinued over the next year based on spot blood glucose concentrations that revealed euglycemia or hypoglycemia. After discontinuation, the dog remained free of clinical signs for 1 year until it was again presented for polyuria/polydipsia with fasting hyperglycemia and glucosuria. Insulin therapy was resumed and continued for the remainder of the dog's life. Although diabetic remission often occurs in cats and humans, the presumed etiopathogenesis of pancreatic beta cell loss makes remission rare in dogs, except for cases occurring with diestrus or pregnancy. This case demonstrates that diabetic remission is possible in dogs, even in cases without an identifiable reversible trigger.

An exceptional cause of polyuria-polydipsia syndrome in a 10-year-old boy.

Polyuria-polydipsia syndrome is a frequent symptom in pediatrics, primarily attributed to diabetes mellitus. In the context of diabetes insipidus, this syndrome can stem from central or nephrogenic factors. Sjögren's syndrome, an uncommon autoimmune disease in children, can affect multiple organs. Kidney involvement as described in adults is usually related to glomerular or tubular impairment, often linked to distal tubular acidosis. As a kidney involvement during childhood, Sjögren's syndrome has rarely been reported. Hereby, we present the case of Sjögren's syndrome revealed by polyuria-polydipsia syndrome in a 10-year-old boy.

Hypodipsic hypernatremia after long-standing polydipsia in a cat with suspect neonatal head trauma.

A 16-month-old neutered male domestic shorthair cat weighing 2.7 kg was referred for further evaluation of acute generalized muscle weakness and paraparesis after a long-standing history of polyuria-polydipsia. The diagnosis of hypodipsic/adipsic hypernatremia relied on the key findings of absent spontaneous drinking despite hypernatremia and a hyperosmolar state (444.8 mOsm/kg, reference interval 280 to 310 mOsm/kg). Brain MRI revealed severe multifocal anatomic anomalies of the rostral calvarium and the forebrain, suggestive of encephaloclastic porencephaly. Involvement of the thalamic and hypothalamic regions could have been responsible for the cat's adipsic hypernatremia. The unique aspects of this case were the rare description of central nervous system disease leading to hypodipsia, and the history of chronic polydipsia before the acute onset of hypodipsia. Key clinical message: Multifocal abnormalities of the forebrain can present with polyuria-polydipsia syndrome, hypodipsia/adipsia, or both, depending on the stage of the disease. This likely happens when the hypothalamic and thalamic regions are affected, since they regulate antidiuretic hormone release and thirst, respectively.

Hypernatrémie hypodipsique après polydipsie ancienne chez un chat suspect de traumatisme crânien néonatal. Un chat domestique à poil court mâle castré âgé de 16 mois et pesant 2,7 kg a été référé pour une évaluation plus approfondie de faiblesse musculaire aiguë généralisée et de paraparésie après une longue histoire de polyurie-polydipsie. Le diagnostic d'hypernatrémie hypodipsique/adipsique reposait sur les principales conclusions de l'absence d'abreuvement spontané malgré l'hypernatrémie et un état hyperosmolaire (444,8 mOsm/kg, intervalle de référence de 280 à 310 mOsm/kg). L'IRM du cerveau a révélé des anomalies anatomiques multifocales sévères de la calotte crânienne rostrale et du prosencéphale évoquant une porencéphalie encéphaloclastique. L'atteinte des régions thalamique et hypothalamique pourrait être responsable de l'hypernatrémie adipsique du chat. Les aspects uniques de ce cas étaient la description rare d'une maladie du système nerveux central conduisant à l'hypodipsie, et l'histoire de la polydipsie chronique avant l'apparition aiguë de l'hypodipsie.Message clinique clé :Les anomalies multifocales du cerveau antérieur peuvent présenter un syndrome de polyurie-polydipsie, une hypodipsie/adipsie, ou les deux, selon le stade de la maladie. Cela se produit probablement lorsque les régions hypothalamique et thalamique sont affectées, car elles régulent respectivement la libération d'hormone antidiurétique et la soif.(Traduit par Dr Serge Messier).

Arginine or Hypertonic Saline-Stimulated Copeptin to Diagnose AVP Deficiency.

BACKGROUND: Distinguishing between arginine vasopressin (AVP) deficiency and primary polydipsia is challenging. Hypertonic saline-stimulated copeptin has been used to diagnose AVP deficiency with high accuracy but requires close sodium monitoring. Arginine-stimulated copeptin has shown similar diagnostic accuracy but with a simpler test protocol. However, data are lacking from a head-to-head comparison between arginine-stimulated copeptin and hypertonic saline-stimulated copeptin in the diagnosis of AVP deficiency. METHODS: In this international, noninferiority trial, we assigned adult patients with polydipsia and hypotonic polyuria or a known diagnosis of AVP deficiency to undergo diagnostic evaluation with hypertonic-saline stimulation on one day and with arginine stimulation on another day. Two endocrinologists independently made the final diagnosis of AVP deficiency or primary polydipsia with use of clinical information, treatment response, and the hypertonic-saline test results. The primary outcome was the overall diagnostic accuracy according to prespecified copeptin cutoff values of 3.8 pmol per liter after 60 minutes for arginine and 4.9 pmol per liter once the sodium level was more than 149 mmol per liter for hypertonic saline. RESULTS: Of the 158 patients who underwent the two tests, 69 (44%) received the diagnosis of AVP deficiency and 89 (56%) received the diagnosis of primary polydipsia. The diagnostic accuracy was 74.4% (95% confidence interval [CI], 67.0 to 80.6) for arginine-stimulated copeptin and 95.6% (95% CI, 91.1 to 97.8) for hypertonic saline-stimulated copeptin (estimated difference, -21.2 percentage points; 95% CI, -28.7 to -14.3). Adverse events were generally mild with the two tests. A total of 72% of the patients preferred testing with arginine as compared with hypertonic saline. Arginine-stimulated copeptin at a value of 3.0 pmol per liter or less led to a diagnosis of AVP deficiency with a specificity of 90.9% (95% CI, 81.7 to 95.7), whereas levels of more than 5.2 pmol per liter led to a diagnosis of primary polydipsia with a specificity of 91.4% (95% CI, 83.7 to 95.6). CONCLUSIONS: Among adult patients with polyuria polydipsia syndrome, AVP deficiency was more accurately diagnosed with hypertonic saline-stimulated copeptin than with arginine-stimulated copeptin. (Funded by the Swiss National Science Foundation; CARGOx ClinicalTrials.gov number, NCT03572166.).

Hypoglycemic Effect of an Herbal Decoction (Modified Gangsimtang) in a Patient with Severe Type 2 Diabetes Mellitus Refusing Oral Anti-Diabetic Medication: A Case Report.

There is growing interest in alternative therapies for type 2 diabetes mellitus (T2DM) because some patients refuse to receive conventional therapies. In East Asia, herbal medicines are often used to treat T2DM, and modified Gangsimtang (mGST) is prescribed to treat a condition called wasting thirst (), which resembles T2DM. This study reported the treatment of hyperglycemia using herbal medicines without oral hypoglycemic agents or insulin therapy. Case presentation: A 36-year-old man with obesity was diagnosed with T2DM four years prior to hospitalization and experienced blood glucose level reduction from 22.2-27.8 mmol/L (400-500 mg/dL) to 5.6-11.1 mmol/L (100-200 mg/dL) by using herbal medicines. He visited D Korean Medicine Hospital with chronic polydipsia and general weakness as chief complaints. He was diagnosed with T2DM on the basis of a hemoglobin A1c level of 11.7% and 2 h postprandial blood glucose level of >25.0 mmol/L (450 mg/dL). Moreover, he was diagnosed with a "dual deficiency of qi and yin" () because of ordinary symptoms (). During his 30-day inpatient treatment, the patient received mGST 120 mL thrice daily; as a result, his postprandial blood glucose level decreased from 25.3 mmol/L (455 mg/dL) to 8.6 mmol/L (154 mg/dL), polydipsia decreased (visual analog scale score decreased from six to one), and triglyceride levels decreased from 11.7 mmol/L (1031 mg/dL) to 2.0 mmol/L (174 mg/dL). Plasma glucose levels remained stable for 6 months after the treatment, and no adverse events were observed over 200 days. We administered an herbal decoction to decrease plasma glucose levels without using oral hypoglycemic agents or insulin. Conclusions: Herbal decoctions such as mGST can reduce hyperglycemia in patients with T2DM who refuse conventional therapy.

Perception and usage of short-term prednisone and prednisolone in dogs.

BACKGROUND: Corticosteroids are widely used with low rates of reported side effects and a broad level of comfort in the hands of most veterinarians. With a low side effect reporting level of < 5% and high level of comfort there may be complacency and underestimation of the impact side effects of corticosteroids may have on a pet and pet owner. OBJECTIVE: The objective of this clinical study was to describe the experience and perception of an owner who administered anti-inflammatory doses of oral prednisolone and prednisone to their dog for up to 14 days. We hypothesized dogs receiving anti-inflammatory doses of prednisone and prednisolone would experience much greater rates of side effects by day 14 then reported in current literature. ANIMALS: There were 45 dogs initially enrolled in the study. RESULTS: At each study point, 31 owners provided results. On day 5, 74% (23/31) reported at least 1 change in their dog's behavior including polyuria, polydipsia, polyphagia, polypnea and/or increased vocalization, with 11 individuals (35%) reporting these changes greatly increased. On day 14, 90% of owners (28/31) reported at least 1 change in their dog's behavior including polyuria, polydipsia, polyphagia, and/or polypnea as the most common changes noted. Overall, 61% (19/31) of owners reported an increase in filling of the water bowl over baseline and one-third (11/31) of pet owners reported cleaning up urinary accidents for pets who had been continent prior to the start of the study. Pet owner steroid satisfaction remained high through day 14 at 4.5/5 (1 = very unsatisfied, 5 = very satisfied). CONCLUSION: This study highlights the impact short term anti-inflammatory doses of prednisone or prednisolone have on dog behaviour and confirms our hypothesis that by day 14, 90% of dogs experienced one or more behaviour changes, with polyuria and polydipsia most commonly reported. Adverse events were noted regardless of starting dosage or regimen. Although most pet owners expressed satisfaction with steroid treatment due to its high efficacy, 70% would select a more costly treatment if that treatment had fewer side effects.

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.

A Clinical and Biochemical Comparative Study Of Diabetic Ketoacidosis (DKA) in Newly Diagnosed Vs Known Cases of Type 1 Diabetic Children.

Objectives: We aimed to study the characterizing clinical and biochemical profiles of Diabetic Ketoacidosis (DKA) in children with newly diagnosed Type 1 Diabetes Mellitus (Type 1DM) compared to children with established diagnosis of Type 1DM presenting with DKA admitted to the pediatric intensive care unit of a large university hospital in the eastern region of Saudi Arabia. Methods: We retrospectively reviewed the medical records of 211 patients who were admitted to the pediatric intensive care unit with diabetic ketoacidosis between 2010 and 2019. The diagnosis of diabetic ketoacidosis was based on symptoms of polydipsia, polyurea, weight loss, vomiting, dehydration, abdominal pain, breathing problems, lethargy or coma, biochemical hyperglycemia (blood glucose level of >200 mg/dL), venous pH of <7.3, serum bicarbonate level of ≤15 mEq/L, and ketonemia (blood ß -hydroxybutyrate concentration of ≥3 mM) or moderate or severe ketonuria (diagnosed as newly acquired type 1 diabetes). Results: The rate of newly diagnosed Type 1 DM with DKA was 41.7%, out of them who got severe and moderate diabetic ketoacidosis were 61.6% and 38.4%, respectively. We observed significantly increased heart and respiratory rates in patients newly diagnosed with diabetic ketoacidosis and in those with severe diabetic ketoacidosis (p<0.001) compared to known cases with Type 1DM presenting with DKA. We also identified significantly increased biochemical indices including HbA1c, random blood sugar, serum osmolality, blood urea nitrogen, creatinine, chloride, lactate, and anion gap in relation to severe diabetic ketoacidosis and newly diagnosed type 1 diabetes (p ≤ 0.05). Conclusions: We found that the clinical and biochemical profiles of patients with newly diagnosed Type 1 DM children were significantly affected compared to children who were known Type 1DM presenting with DKA.

Transient distal renal tubular acidosis with nephrogenic diabetes insipidus after general anaesthesia in a dog.

A 3-year-old, 3.5 kg, female spayed Pomeranian was referred due to persistent vomiting, anorexia, polyuria and polydipsia, 7 days after receiving general anaesthetic for a medial patellar luxation correction. Physical examination revealed lethargy, tachypnoea and 7% dehydration. Complete blood count and serum chemistry results were unremarkable, and venous blood gas analysis revealed hypokalaemia and hyperchloraemic metabolic acidosis with a normal anion gap. Urinalysis revealed a urine specific gravity (USG) of 1.005, pH of 7.0 and proteinuria, and the bacterial culture was negative. Based on these results, the dog was diagnosed with distal renal tubular acidosis, and potassium citrate was prescribed to correct metabolic acidosis. In addition, concurrent diabetes insipidus (DI) was suspected because the dog showed persistent polyuria, polydipsia and a USG below 1.006 despite dehydration. After 3 days of initial treatment, acidosis was corrected, and vomiting resolved. Desmopressin acetate and hydrochlorothiazide were also prescribed for DI, but the USG was not normalized. Based on the insignificant therapeutic response, nephrogenic DI was highly suspected. DI was resolved after 24 days. This case report describes the concomitant presence of RTA and DI in a dog after general anaesthesia.

Lack of sex and estrous stage effects on compulsive behavior assessed using a schedule-induced polydipsia procedure in rats.

Preclinical behavior models used for screening pharmacological treatments for mental disorders have generally used only male research subjects, and for studies that have included female subjects, few have utilized sex as a study variable. In fact, many mental disorders vary by prevalence and symptomatology between sexes, creating a need to evaluate established subject models for sex differences. Compulsive behavior is a feature shared across many mental disorders and effective treatments have been examined pre-clinically using the schedule-induced polydipsia procedure in rats. Drugs effective for reducing polydipsia include psychostimulants, such as d -amphetamine. Virtually no studies have examined sex differences using this procedure. For the present study, male and female rats were examined in the schedule-induced polydipsia paradigm. Rats were food-restricted and trained on a fixed-interval food reinforcement schedule and given free access to water during experimental sessions. Estrous stages were assessed during training and test sessions. The psychostimulant d -amphetamine was also tested once stable water consumption occurred. Excessive water intake developed over the course of training. Females required significantly more sessions to reach a stable level of drinking. Treatment with d -amphetamine (1.0 mg/kg, but not 0.25 or 0.5 mg/kg) significantly reduced drinking in both male and female rats. No sex differences were observed across other study variables including comparisons between diestrus and proestrus stages. Overall, these findings suggest that schedule-induced polydipsia procedures that employ similar methods can produce results generalizable across male and female subjects.

Iatrogenic Cushing syndrome in a child due to erroneous compounding of omeprazole containing glucocorticoid: A case report and literature review.

A 3-month-old infant was examined for inconsolable crying with polydipsia, polyuria, and rapid weight gain. Unexpectedly, the symptoms resolved spontaneously during hospitalization but were aggravated 2 weeks after discharge, with the patient presenting a Cushingoid appearance. Investigations ruled out diabetes mellitus and nephrogenic diabetes insipidus but indicated adrenocortical suppression by exogenous glucocorticoids, which were discovered via toxicologic analysis of her previously compounded omeprazole suspension. After discontinuing the omeprazole suspension, the infant recovered fully and the laboratory results normalized. This case shows us that the assumption of appropriate medication intake may conceal unexpected medication errors. Following this case, the current literature on the benefits and risks of compounding and its impact on patient health is discussed.

Diabetic ketoacidosis in pregnancy.

The clinical presentation of diabetic ketoacidosis (DKA) includes nausea, vomiting, thirst, polyuria, polydipsia, abdominal pain, tachypnoea, and change in mental status in cases of severe DKA. DKA is similar in pregnant and non-pregnant women, but in pregnant women it can be seen at lower serum glucose levels and symptoms may develop more rapidly. Most, but not all, cases occur in the second or third trimester.DKA results in reduction in uteroplacental blood flow due to osmotic diuresis, and also in metabolic abnormalities (maternal acidosis, hyperglycaemia, electrolyte imbalance), resulting in fetal hypoxaemia and acidosis. In fetuses with mature cardiac activity, the fetal heart rate may show minimal or absent variability, repetitive deceleration and absence of acceleration. These abnormalities in heart rate usually resolve with resolution of the DKA, which may last for several hours before normalisation.For the patient reported on here, immediate delivery based on pathological fetal heart rate would have resulted in preterm delivery and jeopardised the maternal clinical condition. However, a holistic clinical approach by the multidisciplinary team to management of the patient led to normal term delivery 5 weeks after presentation with DKA; fetal and maternal outcome were good.

Mutual facilitation between activity-based anorexia and schedule-induced polydipsia in rats.

The objective of this study was to evaluate the possible relationship between drinking (licks) in the schedule-induced polydipsia (SIP) phenomenon and running (turns in the wheel) in the activity-based anorexia (ABA) one. Within-subjects counterbalanced experiments were designed with male Wistar rats which underwent both behavioral procedures; half of them performed the ABA procedure first and the other half the SIP procedure first. In Experiment 1, the initial development of ABA facilitated the subsequent acquisition of SIP, whereas the first acquisition of SIP retarded the subsequent development of ABA. Given that SIP exposure implied food restriction, it could be that adaptation to the food regime contributed to lowering ABA manifestation. Thus, Experiment 2 was carried out in exactly the same way as Experiment 1, with the exception that animals which first went through SIP prior to undergoing the ABA procedure had no food restriction. In this case, both ABA and SIP as first experiences facilitated the further development of SIP and ABA, respectively. This suggests that running in ABA may be functionally similar to drinking in SIP; therefore, both behaviors can be thought of as induced by the schedule/regime of intermittent food availability.

Intractable hyponatremia complicated by a reset osmostat: a case report.

BACKGROUND: Hyponatremia associated with a low serum osmolality is a common and confounding electrolyte disorder. Correcting hyponatremia is also complicated, especially in the setting of chronic hyponatremia. Here, we provide a rational approach to accurately detecting and safely treating acute on chronic euvolemic hyponatremia in the setting of acute polydipsia with a chronic reset osmostat. CASE PRESENTATION: A 71-year-old hispanic gentleman with chronic hyponatremia presented with hiccups, polydipsia, and a serum sodium concentration of 120 mEq/L associated with diffuse weakness, inattentiveness, and suicidal ideation. Symptomatic euvolemic hyponatremia warranted hypertonic saline treatment in the acute phase and water restriction in the chronic phase. Both interventions resulted in improvement in symptoms and/or the serum sodium concentration, but to a serum sodium level that persistently remained below the normal range. Remarkably, the urine osmolality appropriately fell when the serum sodium concentration fell below 126 mEq/L. Also remarkable was the appropriate increase in urine osmolality when the serum sodium concentration exceeded 126 mEq/L. The preservation of both concentration and dilution, albeit at a lower-than-normal serum osmolality, shows that the osmostat regulating antidiuretic hormone release had been "reset." Both physiologic and pharmacologic resetting of the osmostat are discussed. CONCLUSIONS: Preservation of urinary concentrating and diluting ability at a lower-than-normal serum sodium concentration, especially in the setting of chronic hyponatremia, is diagnostic of a reset osmostat. The presence of a reset osmostat often confounds the treatment of concomitant acute hyponatremia. Early recognition of a reset osmostat avoids the need to normalize serum sodium concentration, expedites hospital discharge, and limits potential harm from overcorrecting acute hyponatremia.

Intracranial germinoma in the lateral ventricle with polydipsia and polyuria: a case report and literature review.

Central nervous system germ cell tumors (CNSGCTs) are rare neoplasms which usually develop in the midline structures. They are occasionally involved in off-midline structures of the brain. Here, we report an extremely rare case of an intracranial germinoma in the lateral ventricle. The patient was a 10-year-old boy with a 1-year history of polydipsia and polyuria. Brain magnetic resonance imaging (MRI) showed a relatively homogeneously enhancing lesion in the lateral ventricle, and the posterior pituitary gland was not hyperintense on T1-weighted imaging. Subependymoma was suspected, and tumor removal operation was performed; however, because the intraoperative pathological investigation revealed germinoma, we could only perform partial removal of the tumor. Postoperative histology also confirmed germinoma. Then, the patient received chemotherapy, followed by radiation therapy. MRI showed no recurrence for 6 years after treatment. Intracranial germinoma in the lateral ventricle is extremely rare. The diagnosis is occasionally challenging, especially when the tumors are located in atypical locations. This paper presents a literature review of previously described CNSGCTs of the lateral ventricle to improve awareness of CNSGCTs in atypical locations. We also consider the relationship between imaging findings and clinical manifestations.