Refractory hyponatremia in neuromyelitis optica in a pediatric patient: A case report.

RATIONALE: Neuromyelitis optica spectrum disorders (NMOSD) is a rare autoimmune disease predominantly involving optic nerves and spinal cord, and possible comorbidities including syndrome of inappropriate antidiuretic hormone secretion or urinary complication. We reported a young girl diagnosed with NMOSD presented with refractory hyponatremia, acute urine retention, and general weakness. Clinical symptoms improved gradually after receiving intravenous immunoglobulin, high-dose methylprednisolone, and plasmapheresis. NMOSD should be kept in mind in adolescence with acute urine retention, intermittent fever, and hyponatremia. PATIENT CONCERNS: A 15-year-old girl admitted to our hospital due to no urination for 2 days. DIAGNOSIS: Aquaporin-4 antibodies were detected showing positive both in serum and cerebrospinal fluid. Long transverse myelitis in cervical and thoracic spinal cord and optic neuritis was revealed in magnetic resonance imaging. INTERVENTIONS: Intravenous immunoglobulin 2 g/kg was infused totally in 4 days, and methylprednisolone pulse therapy was subsequently followed in 5 days; followed by 5 courses of plasmapheresis a week later. OUTCOMES: Her muscle power, syndrome of inappropriate antidiuretic hormone secretion condition, and urinary function were all improved after immune-modulated treatment course; NMOSD relapsed twice within the first year after diagnosis, however no relapse of NMOSD in the subsequent 1 year. LESSONS: To the best of our knowledge, this was the first childhood case of NMO accompanied by refractory hyponatremia in the reported literature. In childhood cases presenting with refractory hyponatremia and limb weakness, NMO or NMOSD should be considered possible diagnoses despite their rarity in pediatric cases.

Hiponatremia hipotónica. Diagnóstico diferencial / Hypotonic hiponatremia. Differential diagnosis

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Inpatient hyponatraemia: adequacy of investigation and prevalence of endocrine causes.

This study assessed the effect of endocrine input on the investigation of hyponatraemia and examined the prevalence of endocrine causes of hyponatraemia. This single-centre, retrospective study included 139 inpatients (median age, 74 years) with serum sodium (Na) levels ≤128 mmol/l during hospitalisation at a UK teaching hospital over a three-month period. In total, 61.9% of patients underwent assessment of volume status and 28.8% had paired serum and urine osmolality, and Na measured. In addition, 14.4% of patients received endocrine input; 80% of these patients underwent full work-up of hyponatraemia compared with 5% of patients not referred to endocrine services (p < 0.001; relative risk, 15.86; 95% confidence interval, 7.17-31.06). The prevalence of adrenal insufficiency was 0.7%, but basal serum cortisol levels were not measured in around two-thirds of patients. Despite 26.7% of patients having abnormal thyroid function tests, no patient was diagnosed with severe hypothyroidism. More widespread provision of expert input should be considered.

Hyponatremia: pathophysiology, classification, manifestations and management.

Hyponatremia has complex pathophysiology, is frequent and has potentially severe clinical manifestations, and its treatment is associated with high risks. Hyponatremia can be hypertonic, isotonic or hypotonic. Hypotonic hyponatremia has multiple etiologies, but only two general mechanisms of development, defective water excretion, usually because of elevated serum vasopressin levels, or excessive fluid intake. The acute treatment of symptomatic hypotonic hyponatremia requires understanding of its targets and risks and requires continuous monitoring of the patient's clinical status and relevant serum biochemical values. The principles of fluid restriction, which is the mainstay of management of all types of hypotonic hyponatremia, should be clearly understood and followed. Treatment methods specific to various categories of hyponatremia are available. The indications and risks of these treatments should also be well understood. Rapid correction of chronic hypotonic hyponatremia may lead to osmotic demyelination syndrome, which has severe clinical manifestations, and may lead to permanent neurological disability or death. Prevention of this syndrome should be a prime concern of the treatment of hypotonic hyponatremia.

Hyponatremia caused by polydipsia.

Hyponatremia (serum sodium <135 mEq/L) is the most common electrolyte disorder. The severity of symptoms is related to how rapidly the condition develops and the degree of cerebral edema that results from the low serum level of sodium. Hypertonic saline and the new vasopressin receptor antagonists are highly effective treatments for severe symptomatic hyponatremia, yet they can result in severe neurological complications if sodium levels are restored too quickly. Hyponatremia is classified as hypovolemic, euvolemic, and hypervolemic. Treatments include administration of high-risk medications and fluid restriction to restore fluid and electrolyte balance and relieve cerebral effects. Nursing care to ensure safe outcomes involves multidisciplinary collaboration, close monitoring of serum sodium levels and intake and output, and assessment for neurological changes.

[Hyponatremic syndrome]. / Sindrome iponatriemica.

Sodium, the most important extracellular fluid electrolyte, is the focus of several homeostatic mechanisms that regulate fluid and electrolyte balance. Hyponatremia is a common electrolyte abnormality caused by an actual sodium deficiency or extracellular compartment fluid excess. Clinical symptoms are related with acuity and speed with which this abnormality is established. The symptoms are mainly neurological and neuromuscular disorders (headache, confusion, stupor, seizures, coma) due to brain cells edema. Hyponatremia due to sodium deficiency is caused by sodium loss from kidney (nephritis, diuretics, mineralocorticoid deficiency) and / or extrarenal (vomiting, diarrhea, burns). Hyponatremia due to water excess seems to be the most common and it is attributable to cirrhosis, nephrotic syndrome, heart failure, infusion 5% glucose solutions and drugs that stimulate ADH secretion. It was recently highlighted the role of inflammation and IL-6 in the non-osmotic ADH release. Hyponatremia is considered also marker of phlogosis. Acute (<48 h) and severe (<125 mEq/ L) hyponatremia is a medical emergency that requires prompt correction. Patients with chronic hyponatremia have a high risk of osmotic demyelination syndrome if rapid correction of the plasmatic sodium occurs. In combination with conventional therapy, a new class of drugs, vasopressin receptors antagonists (AVP-R antagonists) would be able to increase the excretion of electrolyte-free water and the serum sodium concentration.

[Hyponatremia: classification and differential diagnosis]. / Hiponatremia: clasificación y diagnóstico diferencial.

Hyponatremia is the most common electrolyte disturbance. This disorder is usually produced by water retention due to the patient's inability to balance water excretion with ingestion of liquids. The present article provides basic information on the physiopathology and epidemiology of hyponatremia in certain contexts such as the ambulatory and hospitalized settings, the geriatric population, exercise-induced hyponatremia, drug-induced hyponatremia and finally hyponatremia observed in some common diseases such as heart failure, liver cirrhosis, pneumonia and HIV infection. The differential diagnosis of hyponatremia should include plasma osmolality, which can be increased, normal or decreased. Most true hyponatremias are grouped in the latter category. If the extracellular volume is decreased, urinary sodium concentrations can be either low or normal with dehydration in the former and water retention in the latter. In hyponatremia with normal extracellular volume, there is free water retention due to a series of stimuli. This entity is seen mainly in hospitalized patients with hypothyroidism or syndrome of inappropriate secretion of antidiuretic hormone. Hyponatremia is underdiagnosed and, more seriously, undertreated, despite numerous studies demonstrating its devastating effects on hospital admissions. The most useful laboratory tests for its diagnosis are urinary sodium concentration, plasma osmolality and urinary osmolality.

Hiponatremia: clasificación y diagnóstico diferencial / Hyponatremia: classification and differential diagnosis

La hiponatremia es la alteración electrolítica más frecuente que existe. En la inmensa mayoría de los casos se produce una retención de agua debida a una incapacidad del sujeto para equilibrar la excreción con la ingestión de líquido. Se proporcionan aspectos básicos acerca de la fisiopatología y la epidemiología de la hiponatremia en algunos contextos, como el entorno ambulatorio y el hospitalario, la población anciana, la hiponatremia asociada a fármacos y al ejercicio, o la que se observa en enfermedades frecuentes, como la insuficiencia cardíaca, la cirrosis hepática, la neumonía y la infección por el virus de la inmunodeficiencia humana. Para el diagnóstico diferencial de la hiponatremia se debe tener en cuenta la osmolalidad plasmática: elevada, normal o baja. En este último caso, es donde se encuadran las verdaderas hiponatremias que con mayor frecuencia se encuentran en la práctica clínica. Si el volumen extracelular está disminuido, nos podemos encontrar ante situaciones con concentraciones urinarias de sodio bajas, en las que hay una deshidratación del paciente, o normales, en las que predomina una retención de agua. En la hiponatremia con volumen extracelular normal se produce una retención anormal de agua libre por diferentes estímulos. Es típico de pacientes hospitalizados, caso del hipotiroidismo y del síndrome de secreción inadecuada de hormona antidiurética. La hiponatremia está infradiagnosticada y, lo que es peor, infratratada a pesar de que son numerosas las investigaciones que han demostrado que sus repercusiones sobre el ingreso hospitalario son devastadoras. Los parámetros de laboratorio de mayor utilidad en su diagnóstico son la concentración urinaria de sodio, la osmolalidad plasmática y la osmolalidad urinaria (AU)

Hyponatremia is the most common electrolyte disturbance. This disorder is usually produced by water retention due to the patient's inability to balance water excretion with ingestion of liquids. The present article provides basic information on the physiopathology and epidemiology of hyponatremia in certain contexts such as the ambulatory and hospitalized settings, the geriatric population, exercise-induced hyponatremia, drug-induced hyponatremia and finally hyponatremia observed in some common diseases such as heart failure, liver cirrhosis, pneumonia and HIV infection. The differential diagnosis of hyponatremia should include plasma osmolality, which can be increased, normal or decreased. Most true hyponatremias are grouped in the latter category. If the extracellular volume is decreased, urinary sodium concentrations can be either low or normal with dehydration in the former and water retention in the latter. In hyponatremia with normal extracellular volume, there is free water retention due to a series of stimuli. This entity is seen mainly in hospitalized patients with hypothyroidism or syndrome of inappropriate secretion of antidiuretic hormone. Hyponatremia is underdiagnosed and, more seriously, undertreated, despite numerous studies demonstrating its devastating effects on hospital admissions. The most useful laboratory tests for its diagnosis are urinary sodium concentration, plasma osmolality and urinary osmolality (AU)

Hyponatremia in heart failure.

Hyponatremia is one of the newer and emerging risk factors for an adverse prognosis in chronic heart failure. Why decreased serum sodium is associated with worse prognosis remains unclear. It may reflect worsening heart failure and the deleterious effects of activation of neurohormones. The mechanism of hyponatremia in heart failure also remains unclear. A relatively greater degree of free-water retention compared to sodium retention is probably the major mechanism. The treatment of significant hyponatremia in heart failure is difficult. The conventional treatments such as fluid restriction, infusion of hypertonic saline, and aggressive diuretic therapies are not usually effective. Vasopressin receptor antagonists have been shown to enhance aquaresis and correct hyponatremia. However, long-term beneficial effects of such treatments in chronic heart failure have not been documented.

Sensitivity of International Classification of Diseases codes for hyponatremia among commercially insured outpatients in the United States.

BACKGROUND: Administrative claims are a rich source of information for epidemiological and health services research; however, the ability to accurately capture specific diseases or complications using claims data has been debated. In this study, the authors examined the validity of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes for the identification of hyponatremia in an outpatient managed care population. METHODS: We analyzed outpatient laboratory and professional claims for patients aged 18 years and older in the National Managed Care Benchmark Database from Integrated Healthcare Information Services. We obtained all claims for outpatient serum sodium laboratory tests performed in 2004 and 2005, and all outpatient professional claims with a primary or secondary ICD-9-CM diagnosis code of hyponatremia (276.1). RESULTS: A total of 40,668 outpatient serum sodium laboratory results were identified as hyponatremic (serum sodium < 136 mmol/L). The sensitivity of ICD-9-CM codes for hyponatremia in outpatient professional claims within 15 days before or after the laboratory date was 3.5%. Even for severe cases (serum sodium < or = 125 mmol/L), sensitivity was < 30%. Specificity was > 99% for all cutoff points. CONCLUSION: ICD-9-CM codes in administrative data are insufficient to identify hyponatremia in an outpatient population.

Current issues for nurse practitioners: Hyponatremia.

PURPOSE: To review the assessment, diagnosis, and management of hyponatremia (serum sodium <135 mEq/L), the most common electrolyte disturbance as a result of dysregulation of water balance in hospitalized or institutionalized patients. DATA SOURCES: Comprehensive search using keywords AVP receptor antagonists, hyponatremia, SIADH, conivaptan, tolvaptan, lixivaptan, nurse practitioner, and others was carried out using the National Library of Medicine (PubMed) Web site from which full-text articles were obtained. Meeting abstracts were obtained from scientific sessions including the American Society of Nephrology Renal Week 2004 and the Endocrine Society's 87th Annual Meeting (2005). The Vaprisol (conivaptan hydrochloride injection) package insert was referenced and obtained from FDA.gov. CONCLUSIONS: A diagnosis of hyponatremia requires thorough investigation for underlying causes and prompt treatment to prevent poor patient outcomes. In clinical trials, a new class of drugs called the arginine vasopressin (AVP) receptor antagonists or aquaretics has been shown to be safe and effective for the treatment of hyponatremia. Among this class of agents, intravenous conivaptan hydrochloride, indicated for the treatment of euvolemic hyponatremia in hospitalized patients, is the first drug in class approved for use. IMPLICATIONS FOR PRACTICE: Elderly patients, and those with certain conditions such as heart failure, tuberculosis, cirrhosis, and head injury, may be at increased risk for hyponatremia. In hospitalized patients following surgery and the use of certain medications, hyponatremia is a common condition. A thorough understanding of the physiology of water balance and the risk factors associated with hyponatremia is essential for prompt and effective intervention. Awareness of the limitations of conventional therapies and the availability of new treatment options for hyponatremia allows clinicians to optimize patient care.

Hyponatraemia in clinical practice.

Hyponatraemia is defined as a serum sodium concentration below 135 mmol/l. It causes major diagnostic and management problems in practice. Hyponatraemic disorders are divided into euvolaemic, hypervolaemic and hypovolaemic. In the evaluation of the hyponatraemic patient, history taking should focus on identifying the potential cause, duration and symptomatology. Clinical examination should include assessment of volume status. Acute hyponatraemia of less than 48 h duration requires prompt correction. Treatment may involve hypertonic saline, isotonic saline and appropriate hormone replacement therapy depending on the aetiology. Chronic hyponatraemia should be treated with caution because of the risk of central pontine myelinolysis.

Recognition and treatment of hyponatremia in acutely ill hospitalized patients.

OBJECTIVE: The objective of this paper was to discuss the diagnosis, pathophysiology, and management of hyponatremia among critically ill, hospitalized patients (eg, after surgery or in the intensive care unit). METHODS: English-language literature published between 1967 and 2006 was searched using several key words (AVP receptor antagonists, hyponatremia, SIADH, conivaptan, tolvaptan, and lixivaptan) and by accessing MEDLINE and ScienceDirect. Meeting abstracts from scientific sessions (American Society of Nephrology Renal Week 2004 and the Endocrine Society's 87th Annual Meeting [2005]) were reviewed. The package insert for conivaptan hydrochloride injection was referenced from . Clinical trials included in this review were randomized and placebo controlled. RESULTS: Based on the literature we researched, hyponatremia is the most common electrolyte disorder encountered in critical care and is associated with a variety of conditions, including congestive heart failure and the syndrome of inappropriate antidiuretic hormone secretion. Because hyponatremia can arise in hypervolemic, euvolemic, and hypovolemic states, clinicians may not recognize its presence and cause. Incorrect management can lead to significant morbidity and mortality. Physicians need to recognize risk factors and symptoms and use appropriate treatment guidelines for hyponatremia. Traditionally, therapy for hyponatremia has been limited by efficacy and safety concerns. Arginine vasopressin (AVP) receptor antagonists, therapeutic agents that promote aquaresis in patients with hyponatremia by targeting V(1a) receptors in the vascular smooth muscle, V(2) receptors in the kidney, or both, are under development. A dual-receptor antagonist targeting both V(1a) and V(2) receptors is now approved for the treatment of euvolemic hyponatremia in hospitalized patients. CONCLUSIONS: Hyponatremia, an electrolyte abnormality found in critically ill patients, can be associated with significant morbidity and mortality. AVP receptor antagonists show promise as effective and tolerable treatments for patients with hyponatremia.

Management of hyponatremia and clinical use of vasopressin antagonists.

Hyponatremia, the most common electrolyte disorder in hospitalized patients, has been associated with high rate of mortality among both this population and nonhospitalized patients. This review describes briefly the classification and pathogenesis of hyponatremia, and, in greater detail, the management of hyponatremia with a particular emphasis on the clinical pharmacology of arginine vasopressin (AVP) antagonists. This review includes more in-depth discussion on the pharmacology of conivaptan, an AVP antagonist recently approved by the United States Food and Drug Administration.

Vasopressin-receptor antagonists: a new class of agents for the treatment of hyponatremia.

Hyponatremia is a very common electrolyte disorder often caused by the dysregulation of arginine vasopressin (AVP) secretion and the effects of the hormone at its receptors and is associated with significant morbidity and mortality. Recent developments in the understanding of water homeostasis and AVP actions at the kidney, both in normal circumstances and in pathologic conditions, has created the possibility of new therapies that directly target the inappropriate excess of AVP stimulation of vasopressin V(2) receptors (V2Rs) in the kidney. Preclinical and clinical trial results indicate that AVP V2R antagonism is a highly promising and rational approach for the treatment of dilutional hyponatremia caused by excessive retention of water. This review of hyponatremia and its therapy is intended to educate clinicians who manage patients who have hyponatremia and its complications. Background information on hyponatremia is presented and the pertinent published literature with regard to the diagnosis and therapy of this disorder is summarized with a specific focus on AVP-receptor antagonists. Agents that antagonize AVP V2Rs and promote aquaresis, the electrolyte-sparing excretion of free water, are likely to be effective and well tolerated therapies for the treatment of dilutional hyponatremia.

Hyponatremia: why it matters, how it presents, how we can manage it.

Hyponatremia is a common electrolyte disorder among hospitalized patients and has been associated with increased mortality. Most patients are asymptomatic, but many do present with symptoms, usually of a generalized neurologic nature. Based-on medical history, physical examination (including volume-status assessment), and laboratory tests, patients can be classified as having either hypervolemic, euvolemic, or hypovolemic hyponatremia. Management depends on the speed of hyponatremia onset; its degree, duration, and symptoms; and whether there are risk factors for neurologic complications. The risks of overly rapid correction must be weighed against the benefits of treating hyponatremia. Traditional therapies have significant limitations. New agents that antagonize arginine vasopressin at the V2 receptor or both the V(1A) and V2 receptors show promise for treating hypervolemic and euvolemic hyponatremia, as they induce desired free water diuresis without inducing sodium excretion.