Pearls & Oy-sters: Syndrome of Inappropriate Antidiuretic Hormone Secretion Presenting as Neuromyelitis Optica Spectrum Disorder Flare.

While it was previously believed that neuromyelitis optic spectrum disorder (NMOSD) mostly affected the optic nerves and the spinal cord, it is increasingly recognized that NMOSD can involve any area of the CNS where aquaporin-4 is highly expressed. These other areas can include the hypothalamus and the circumventricular organs that surround the third and fourth ventricles, serving as osmoregulators. The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is one of the most common causes of hyponatremia and has been associated with NMOSD due to these lesions. In this report, we present a case of a patient with known NMOSD, who presented with dizziness, fatigue, and generalized weakness and whose workup revealed hyponatremia in the setting of SIADH and hypothalamic demyelinating lesions. This case illustrates an atypical presentation of NMOSD and the importance of looking for syndromes, such as SIADH. This can guide diagnostic testing, such as getting thin MRI cuts through the hypothalamus and brainstem, as well as advanced management techniques such as immunotherapy.

Intractable hyponatremia secondary to syndrome of inappropriate antidiuresis complicated with empty sella: A case report.

RATIONALE: Hyponatremia is a common electrolyte disorder in elderly critically ill patients, and it may be associated with poor outcomes, higher morbidity, and mortality. Syndrome of inappropriate antidiuresis (SIAD) is one of the main causes of hyponatremia, with an insidious onset that is highly misdiagnosed. Primary empty sella lesions are specific, mostly asymptomatic, and easily overlooked. SIAD combined with empty sella is much rarer in clinic, this article focuses on the diagnosis and management of an elderly patient with intractable hyponatremia secondary to syndrome of inappropriate antidiuresis complicated with empty sella. PATIENT CONCERNS: An 85-year-old male patient with severe pneumonia presented with progressive and intractable hyponatremia. DIAGNOSES: The patient had clinical signs of persistent hyponatremia, low plasma osmolality, elevated urinary sodium excretion, and hyponatremia that worsened with increased intravenous rehydration and was effective with appropriate fluid restriction. The diagnosis of SIAD combined with empty sella was made in combination with the findings of the pituitary and its target gland function. INTERVENTIONS: Numerous screenings were performed to clarify the cause of hyponatremia. His overall condition was poor due to recurrent episodes of hospital-acquired pneumonia. We treated with ventilation support, circulatory support, nutritional support, anti-infection, and continuous correction of electrolyte imbalance. OUTCOMES: His hyponatremia gradually improved through aggressive infection control, appropriate fluid restriction (intake controlled at 1500-2000mL/d), continuous electrolyte correction, supplementation with hypertonic salt solution, and potassium replacement therapy. LESSONS: Electrolyte disorders, especially hyponatremia, are very common in critically ill patients, but the etiology of hyponatremia is challenging to diagnose and treat, and timely attention and proper diagnosis of SIAD and individualized treatment are the significance of this article.

Syndrome of inappropriate secretion of antidiuretic hormone as an initial sign of primary central nervous system lymphomas in the hypothalamus.

BACKGROUND: Primary central nervous system lymphoma (PCNSL) rarely originates in the hypothalamus. Hypothalamic PCNSL can present with various symptoms specific to dysfunction of the hypothalamus, including consciousness disturbance, cognitive impairment, hypopituitarism, and diabetes insipidus (DI). However, it remains unclear whether syndrome of inappropriate secretion of antidiuretic hormone (SIADH) can present as an initial sign of hypothalamic PCNSL. METHODS: Ninety-nine patients with PCNSL were diagnosed between January 2006 and December 2020 at our institutes. The initial symptoms and signs, hypothalamic-pituitary functions, serum sodium (Na) value, Karnofsky Performance Status (KPS) score on admission, and duration from onset to diagnosis were retrospectively investigated from the medical charts. RESULTS: Eight and 91 patients had hypothalamic PCNSL (hypothalamic group) and PCNSL located in other regions (control group), respectively. Patients' pathological diagnoses were diffuse large B-cell lymphoma (97 patients) and intravascular lymphoma (two patients). Six patients presented with hyponatremia derived from SIADH or suspected SIADH, and one presented with DI. Statistically significant differences between the hypothalamic and control groups were detected only in the preoperative serum Na values and KPS scores. CONCLUSION: SIADH can be an initial presentation of hypothalamic PCNSL. Early detection of hypothalamic PCNSL from SIADH may lead to proper management and improved prognosis.

Effect of single-dose of tolvaptan in neurocritical patients with hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion / Efecto de una dosis única de tolvaptán en pacientes neurocríticos con hiponatremia debido a SIADH

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Syndrome of inappropriate antidiuretic hormone accompanied by bilateral hypothalamic and anterior thalamic lesions with serum antiaquaporin 4 antibody.

We described a rare case of the syndrome of inappropriate antidiuretic hormone secretion (SIADH) and severe unconsciousness accompanied by bilateral hypothalamic and anterior thalamic lesions with positive serum antiaquaporin 4 (AQP4) antibody. A 29-year-old man was admitted to our hospital due to the subacute progression of an unconscious state. He was observed to be hyponatraemic secondary to SIADH. Brain MRI showed bilateral hypothalamic and anterior thalamic lesions. Anti-AQP4 antibody was detected in his serum. After the administration of intravenous methylprednisolone pulse therapy, his symptoms improved with complete recovery from SIADH and regression of the hypothalamic and anterior thalamic lesions. The patient was transferred to another hospital for rehabilitation with 20 mg/day of oral prednisolone 127 days after admission. This case highlights the importance of testing for anti-AQP4 antibody in patients with unexplainable SIADH, subacute progressive unconsciousness and bilateral hypothalamic and anterior thalamic lesions.

Salt-sparing diuretic action of a water-soluble urea analog inhibitor of urea transporters UT-A and UT-B in rats.

Inhibitors of kidney urea transporter (UT) proteins have potential use as salt-sparing diuretics ('urearetics') with a different mechanism of action than diuretics that target salt transporters. To study UT inhibition in rats, we screened about 10,000 drugs, natural products and urea analogs for inhibition of rat UT-A1. Drug and natural product screening found nicotine, sanguinarine and an indolcarbonylchromenone with IC50 of 10-20 µM. Urea analog screening found methylacetamide and dimethylthiourea (DMTU). DMTU fully and reversibly inhibited rat UT-A1 and UT-B by a noncompetitive mechanism with IC50 of 2-3 mM. Homology modeling and docking computations suggested DMTU binding sites on rat UT-A1. Following a single intraperitoneal injection of 500 mg/kg DMTU, peak plasma concentration was 9 mM with t1/2 of about 10 h, and a urine concentration of 20-40 mM. Rats chronically treated with DMTU had a sustained, reversible reduction in urine osmolality from 1800 to 600 mOsm, a 3-fold increase in urine output, and mild hypokalemia. DMTU did not impair urinary concentrating function in rats on a low protein diet. Compared to furosemide-treated rats, the DMTU-treated rats had greater diuresis and reduced urinary salt loss. In a model of syndrome of inappropriate antidiuretic hormone secretion, DMTU treatment prevented hyponatremia and water retention produced by water-loading in dDAVP-treated rats. Thus, our results establish a rat model of UT inhibition and demonstrate the diuretic efficacy of UT inhibition.

Clinical practice guideline on diagnosis and treatment of hyponatraemia.

Hyponatraemia, defined as a serum sodium concentration <135 mmol/l, is the most common disorder of body fluid and electrolyte balance encountered in clinical practice. It can lead to a wide spectrum of clinical symptoms, from subtle to severe or even life threatening, and is associated with increased mortality, morbidity and length of hospital stay in patients presenting with a range of conditions. Despite this, the management of patients remains problematic. The prevalence of hyponatraemia in widely different conditions and the fact that hyponatraemia is managed by clinicians with a broad variety of backgrounds have fostered diverse institution- and speciality-based approaches to diagnosis and treatment. To obtain a common and holistic view, the European Society of Intensive Care Medicine (ESICM), the European Society of Endocrinology (ESE) and the European Renal Association - European Dialysis and Transplant Association (ERA-EDTA), represented by European Renal Best Practice (ERBP), have developed the Clinical Practice Guideline on the diagnostic approach and treatment of hyponatraemia as a joint venture of three societies representing specialists with a natural interest in hyponatraemia. In addition to a rigorous approach to methodology and evaluation, we were keen to ensure that the document focused on patient-important outcomes and included utility for clinicians involved in everyday practice.

Clinical practice guideline on diagnosis and treatment of hyponatraemia.

Hyponatraemia, defined as a serum sodium concentration <135 mmol/l, is the most common disorder of body fluid and electrolyte balance encountered in clinical practice. It can lead to a wide spectrum of clinical symptoms, from subtle to severe or even life threatening, and is associated with increased mortality, morbidity and length of hospital stay in patients presenting with a range of conditions. Despite this, the management of patients remains problematic. The prevalence of hyponatraemia in widely different conditions and the fact that hyponatraemia is managed by clinicians with a broad variety of backgrounds have fostered diverse institution- and speciality-based approaches to diagnosis and treatment. To obtain a common and holistic view, the European Society of Intensive Care Medicine (ESICM), the European Society of Endocrinology (ESE) and the European Renal Association - European Dialysis and Transplant Association (ERA-EDTA), represented by European Renal Best Practice (ERBP), have developed the Clinical Practice Guideline on the diagnostic approach and treatment of hyponatraemia as a joint venture of three societies representing specialists with a natural interest in hyponatraemia. In addition to a rigorous approach to methodology and evaluation, we were keen to ensure that the document focused on patient-important outcomes and included utility for clinicians involved in everyday practice.

[Etiology, diagnostics and therapy of hyponatremias]. / A hyponatraemiás állapotok etiológiája, diagnosztikája és terápiája.

Etiopathogenesis, diagnostics and therapy of hyponatremias are summarized for clinicians. Hyponatremia is the most common electrolyte abnormality. Mild to moderate hyponatremia and severe hyponatremia are found in 15-30% and 1-4% of hospitalized patients, respectively. Pathophysiologically, hyponatremias are classified into two groups: hyponatremia due to non-osmotic hypersecretion of vasopressin (hypovolemic, hypervolemic, euvolemic) and hyponatremia of non-hypervasopressinemic origin (pseudohyponatremia, water intoxication, cerebral salt wasting syndrome). Patients with mild hyponatremia are almost always asymptomatic. Severe hyponatremia is usually associated with central nervous system symptoms and can be life-threatening. Diagnostic evaluation of patients with hyponatremia is directed toward identifying the extracellular fluid volume status, the neurological symptoms and signs, the severity and duration of hyponatremia, the rate at which hyponatremia developed. The first step to determine the probable cause of hyponatremia is the differentiation of the hypervasopressinemic and non-hypervasopressinemic hyponatremias with measurement of plasma osmolality, glucose, lipids and proteins. For further differential diagnosis of hyponatremia, the determination of urine osmolality, the clinical assessment of extracellular fluid volume status and the measurement of urine sodium concentration provide important information. The most important representative of euvolemic hyponatremias is SIADH. The diagnosis of SIADH is based on the exclusion of other hyponatremic conditions; low plasma osmolality (<275 mosmol/kg) and inappropriate urine concentration (urine osmolality >100 mosmol/kg) are of pathognomic value. Acute (<48 hrs) severe hyponatremia (<120 mmol/l) necessitates emergency care with rapid restoration of normal osmotic milieu (1 mmol/l/hr increase rate of serum sodium). Patients with chronic symptomatic hyponatremia have a high risk of osmotic demyelination syndrome in brain if rapid correction of the plasma sodium occurs (maximal rate of correction of serum sodium should be 0.5 mmol/l/hr or less). The conventional treatments for chronic asymptomatic hyponatremia (except hypovolemic patients) include water restriction and/or the use of demeclocycline or lithium or furosemide and salt supplementation. Vasopressin receptor antagonists have opened a new forthcoming therapeutic era. V2 receptor antagonists, such as lixivaptan, tolvaptan, satavaptan and the V2+V1A receptor antagonist conivaptan promote the electrolyte-sparing excretion of free water and lead to increased serum sodium.

[Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) associated with relapsing multiple sclerosis].

We report a 47-year-old man with multiple sclerosis (MS) with previous history of recurrent sensorimotor disturbance and visual deficit. The patient developed bilateral motor weakness in the upper limbs, and systemic malaise. An administration of 20 mg/day of prednisolone was ineffective for his symptoms and he complained dyspnea a week later. On admission, his clinical findings included brainstem dysfunction with optic nerve atrophy, motor disturbance in the bilateral upper limbs, hyperreflexia, and superficial sensory disturbance. Biochemical examination revealed marked reduction in serum Na (117 mEq/l) and C1 (85 mEq/l) with increased urinary Na excretion. Although his plasma osmotic pressure decreased to 233 mOsm/kg, urinary osmotic pressure increased to 409 mOsm/kg. Serum antidiuretic hormone (ADH) concentration was 26.1 pg/ml and plasma renin activity was 0.1 ng/ml/ hour. Renal function and adrenal function were normal. Cerebrospinal fluid contained increased protein concentration, IgG, and myelin basic protein. Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) associated with MS was diagnosed. Intravenous Na infusion with restricted supplemental fluid and serial administration of methylprednisolone (1,000 mg/day for three days) improved his neurological abnormalities and normalized his serum serum Na level and plasma osmotic pressure. This suggests that demyelinating lesions in the hypothalamus due to MS may cause the transient increased ADH secretion.

Elevated lead levels in a patient with sickle cell disease and inappropriate secretion of antidiuretic hormone.

A five-year-old girl with known sickle cell disease presented with severe hyponatremia and findings compatible with syndrome of inappropriate secretion of antidiuretic hormone (SIADH). She was found to have lead levels in the Class III category. By exclusion, we postulated that the SIADH was in some way related to the high lead levels, since this was the only abnormality the patient exhibited. The toxic lead levels and the elevated vasopressin levels rapidly responded to dimercaprol and calcium EDTA chelation therapy.

Hyponatremia due to cerebral salt-wasting syndrome. Combined cerebral and distal tubular lesion.

A 76-year-old white man was evaluated for a syndrome of hyponatremia, hypotension, and high urinary sodium excretion. There was evidence of inappropriate secretion of antidiuretic hormone and renal salt wasting in the presence of a normal glomerular filtration rate. He had a distal tubular acidification defect and unresponsiveness to standard doses of mineralocorticoids. The renin aldosterone axis was normal, as were thyroid and adrenal function. The patient could not dilute the urine, nor excrete a standard water load. Renal concentrating ability was normal, but there was no additional response to exogenous vasopressin. With modest salt restitution, the patient continued to lose large quantities of sodium in the urine, resulting in severe postural hypotension. Renal biopsy showed normal glomeruli with distinct degeneration of the distal tubules. There was no evidence of an acute inflammatory interstitial nephritis. The patient did not respond to therapeutic doses of mineralocorticoid (fludrocortisone), but treatment with water restriction, increased salt intake, and large doses of mineralocorticoids resulted in a normal serum sodium level and blood pressure. This case falls in the category of "cerebral salt wasting" syndrome. The cause was a combination of idiopathic secretion of antidiuretic hormone and distal tubular degeneration resulting in pseudohypoaldosteronism.

[Surgery of the hypophyseo-hypothalamic lesions and the circadian rhythm of ADH secretion].

Various clinical disorders of water and electrolytes metabolism were reported in relation to decrease or increase of the plasma anti-diuretic hormone (ADH), however, the estimated ADH value was not infrequently found inconsistent with clinical features. In order to determine the influence from surgical intervention to the hypophyseo-hypothalamic system, continuous estimation of the urinary secretion and specific gravity was performed with computerized analyzer, and it was found that there were at least 5 patterns of postoperative change in rhythmicity of ADH secretion. Most interesting finding was that the ADH was discharged in phasic pattern and irregularly intermingled oligo- and polyuric phases were observed quite in early stage of postoperative observation. Forty cases were examined and this method of examination was found useful in the prognostic view point for the postoperative water and electrolytes disorders.

Hyponatremia in the syndrome of inappropriate secretion of antidiuretic hormone. Rapid correction with urea, sodium chloride, and water restriction therapy.

In the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), rapid elevation of serum sodium concentration may be imperative to correct neurological symptoms. Seven patients with hyponatremia secondary to SIADH were treated by oral intake of two to three doses of 30 g of urea over 24 hours or infusion of 80 g of urea as a 30% solution of over six hours, water restriction (500 mL/24 hr), and sodium supplements (120 to 360 mmole/24 hr). Serum sodium concentration increased from 117 +/- 2 to 126 +/- 1.4 mmole/L (mean +/- SEM) after eight hours, to 130 +/- 1.3 mmole/L after 12 hours, and to 134.5 +/- 1.2 mmole/L after 24 hours. The normalization of serum sodium was secondary to osmotic diuresis and to sodium retention induced by urea. Use of urea should be considered when symptomatic hyponatremia in SIADH must be quickly corrected.

[Disorders of heat and water regulation. Proliferative reticulo granulomatous process of hypothalamic origin (author's transl)]. / Troubles de la régulation thermique et de la régulation hydrique. Processus prolifératif réticulo-granulomateux à détermination hypothalamique.

The authors report the anatomical and clinical findings in a 65 year old patient with a lesion in the hypothalamus presenting mainly as disorders in heat and water regulation. Disorders in heat regulation dominated the clinical picture, in relation to a poikilothermia. Conservation of reactivity to pyrogenic bacteria is debatable. Inappropriate secretion of antidiuretic hormone (ISADH) by a direct effect on the supraoptico-hypophyseal aixs can account for the water and electrolyte disturbances. The anatomical lesions, due to hypothalamic changes, can be included in the circumscribed proliferative reticuloses of the CNS having a pseudo-inflammatory histological appearance.