A syndrome of renal sodium loss and hyponatremia probably resulting from inappropriate secretion of antidiuretic hormone

Identifying Different Causes of Hyponatremia With Fractional Excretion of Uric Acid

BACKGROUND

There is controversy over the prevalence of the syndrome of inappropriate antidiuretic hormone secretion (SIADH) and cerebral or renal salt wasting (RSW), 2 syndromes with identical common clinical and laboratory parameters but different therapies. The traditional approach to the hyponatremic patient relies on volume assessment, but there are limitations to this method.

METHODS

We used an algorithm that relies on fractional excretion of urate (FEurate) to evaluate patients with hyponatremia and present 4 illustrative cases.

RESULTS

Overall, 2 patients had increased FEurate [normal: 4-11%], as is seen in SIADH and RSW. A diagnosis of SIADH was made in 1 patient by correcting the hyponatremia with 1.5% saline and observing a characteristic normalization of an elevated FEurate that is characteristic of SIADH as compared to FEurate being persistently increased in RSW. A patient with T-cell lymphoma had symmetrical leg edema due to lymphomatous obstruction of the inferior vena cava, postural hypotension, pleural effusion, ascites, decreased cardiac output and urine sodium level of 10mmol/L. Saline-induced excretion of dilute urines and undetectable plasma antidiuretic hormone were consistent with RSW. Furosemide, given for presumed heart failure, induced a profound diuresis that required large volumes of fluid resuscitation. A normal FEurate identified a reset osmostat in a transplant patient with a slowly developing pneumocystis carinii pneumonia. A volume-depleted hyponatremic patient with Addison׳s disease had a low FEurate of 1.4%.

CONCLUSIONS

These illustrative cases suggest that an approach to hyponatremia using FEurate may be a useful alternative to traditional volume-based approaches.

Yield of workup for patients with idiopathic presentation of the syndrome of inappropriate antidiuretic hormone secretion

PURPOSE

To determine the proportion of patients for whom the syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the presenting symptom of an underlying disorder, to describe the yield of different diagnostic modalities for patients with SIADH and an unknown etiology, and to define patients for whom such a workup is indicated.

METHODS

A single center retrospective study including all patients diagnosed with SIADH without an apparent etiology in a large community hospital and tertiary center between 1.1.07 and 1.1.13. Two physicians reviewed every patient's medical file for predetermined relevant clinical data.

RESULTS

Eleven of the 99 patients without an apparent etiology for SIADH at presentation were found to have an underlying cause on workup. Yield of performed workup was low, with a pathology demonstrated on 0%-30.8% of tests according to the different modalities used. Patients with presumed idiopathic SIADH at presentation who were later found to have a specific etiology were younger than patients with true idiopathic SIADH, had a significantly shorter duration of hyponatremia prior to SIADH diagnosis, had higher urine osmolality and a clinical presentation suggestive of an undiagnosed disorder.

CONCLUSIONS

Our findings support a clinically-based approach to patients with idiopathic SIADH, rather than an extensive routine workup for all patients.

Paraneoplastic Syndromes in Patients with Cancer of the Larynx and Hypopharynx

Paraneoplastic syndromes may be the first sign of a malignancy. They are systemic, nonmetastatic manifestations associated with a variety of malignant neoplasms and occurring in a minority of cancer patients. These associations of symptoms and signs are not directly related to the site or local manifestations of a malignant tumor or its metastases, but their recognition may facilitate the detection of malignancies or recurrences. Paraneoplastic syndromes are categorized into 6 types: Dermatologic or cutaneous, endocrine, hematologic, neurologic, osteoarticular or rheumatologic, and ocular. Different oncotypes have rarely been associated with paraneoplastic syndromes in patients with cancer of the larynx and hypopharynx. The world literature has been reviewed.

A study of hyponatremia in tuberculous meningitis

SETTING

In view of paucity of studies on predictors of hyponatremia in tuberculous meningitis (TBM) and its influence on outcome, this study was undertaken.

OBJECTIVE

To study the frequency, predictors and prognosis of hyponatremia in TBM.

DESIGN

In this prospective hospital based study, 76 patients with TBM (definite 18 and probable 58) were enrolled. The severity of meningitis was graded as I-III and hyponatremia as severe (<120mEq/L), moderate (120-129mEq/L) or mild (130-134mEq/L). Hospital death was noted and functional outcome was assessed by modified Rankin Scale (mRS) on discharge.

RESULTS

34 (44.7%) TBM patients had hyponatremia (mild 3, moderate 23 and severe 8). Hyponatremia was due to cerebral salt wasting in 17, syndrome of inappropriate secretion of antidiuretic hormone in 3 and miscellaneous causes in 14 patients. Hyponatremia was related to GCS score and basal exudates. Outcome of TBM was related to duration of hospitalization, GCS score, focal deficit, mechanical ventilation, severity of TBM, age and comorbidities. Cerebral salt wasting was related to severity of TBM.

CONCLUSION

Hyponatremia occurred in 44.7% of TBM patients. Cerebral salt wasting was the commonest cause of hyponatremia and was related to the severity of TBM.

Central Diabetes Insipidus and Cisplatin-Induced Renal Salt Wasting Syndrome: A Challenging Combination

We describe a 2-year-old female with a suprasellar primitive neuroectodermal tumor and central diabetes insipidus (DI) who developed polyuria with natriuresis and subsequent hyponatremia 36 hr after cisplatin administration. The marked urinary losses of sodium in combination with a negative sodium balance led to the diagnosis of cisplatin-induced renal salt wasting syndrome (RSWS). The subsequent clinical management is very challenging. Four weeks later she was discharged from ICU without neurological sequela. The combination of cisplatin-induced RSWS with DI can be confusing and needs careful clinical assessment as inaccurate diagnosis and management can result in increased neurological injury.

Diagnosing and Treating the Syndrome of Inappropriate Antidiuretic Hormone Secretion

BACKGROUND

The syndrome of inappropriate antidiuretic hormone secretion is the most common cause of hyponatremia in clinical practice, but current management of hyponatremia and outcomes in patients with syndrome of inappropriate antidiuretic hormone secretion are not well understood. The objective of the Hyponatremia Registry was to assess the current state of management of hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion in diverse hospital settings, specifically which diagnostic and treatment modalities are currently used and how rapidly and reliably they result in an increase in serum sodium concentration ([Na(+)]). A secondary objective was to determine whether treatment choices and outcomes differ across the United States and the European Union.

METHODS

The Hyponatremia Registry recorded selected diagnostic measures and use, efficacy, and outcomes of therapy for euvolemic hyponatremia diagnosed clinically as syndrome of inappropriate antidiuretic hormone secretion in 1524 adult patients with [Na(+)] ≤130 mEq/L (1034 from 146 US sites and 490 from 79 EU sites). A subgroup of patients with more rigorously defined syndrome of inappropriate antidiuretic hormone secretion via measurement of relevant laboratory parameters was also analyzed.

RESULTS

The most common monotherapy treatments for hyponatremia in syndrome of inappropriate antidiuretic hormone secretion were fluid restriction (48%), isotonic (27%) or hypertonic (6%) saline, and tolvaptan (13%); 11% received no active agent. The mean rate of [Na(+)] change (mEq/L/d) was greater for all active therapies than no active treatment. Hypertonic saline and tolvaptan produced the greatest mean rate of [Na(+)] change (interquartile range, both 3.0 [6.0] mEq/L/d) compared with lower interquartile range rates of [Na(+)] change for isotonic saline (1.5 [3.0] mEq/L/d) and fluid restriction (1.0 [2.3] mEq/L/d). The general pattern of responses was similar in both the US and EU cohorts. At discharge, [Na(+)] was <135 mEq/L in 75% of patients and ≤130 mEq/L in 43% of patients. Overly rapid correction occurred in 10.2% of patients.

CONCLUSIONS

Current treatment of hyponatremia in syndrome of inappropriate antidiuretic hormone secretion often uses therapies with limited efficacy; the most commonly chosen monotherapy treatments, fluid restriction and isotonic saline, failed to increase the serum [Na(+)] by ≥5 mEq/L in 55% and 64% of monotherapy treatment episodes, respectively. Appropriate laboratory tests to diagnose syndrome of inappropriate antidiuretic hormone secretion were obtained in <50% of patients; success rates in correcting hyponatremia were significantly higher when such tests were obtained. Few outcome differences were found between the United States and the European Union. A notable exception was hospital length of stay; use of tolvaptan was associated with significantly shorter length of stay in the European Union but not in the United States. Despite the availability of effective therapies, most patients with syndrome of inappropriate antidiuretic hormone secretion were discharged from the hospital still hyponatremic.

Hyponatremia in cancer patients: Time for a new approach

Hyponatremia is a common electrolyte disorder in cancer patients. It may be related to cancer, to anti-cancer therapy or to other concomitant treatments. In this setting hyponatremia is often caused by the syndrome of inappropriate anti-diuretic hormone secretion, which is due to the ectopic production of antidiuretic hormone (vasopressin), to extracellular fluid depletion, to renal toxicity caused by chemotherapy or to other underlying conditions. Recent studies suggested that hyponatremia might be considered a negative prognostic factor for cancer patients therefore its early detection, monitoring and management might improve the patient's outcome. Treatment of hyponatremia depends on patient's symptoms severity, onset timing and extracellular volume status. In this review we summarize the main causes of hyponatremia in cancer patients and its management, including the available treatment options.

A copeptin-based classification of the osmoregulatory defects in the syndrome of inappropriate antidiuresis

The syndrome of inappropriate antidiuretic hormone secretion (SIADH), also referred to as syndrome of inappropriate antidiuresis (SIAD), is the most common cause of hyponatremia characterized by extracellular hypotonicity and impaired urine dilution in the absence of any recognizable nonosmotic stimuli for the antidiuretic hormone arginine vasopressin (AVP). Hyponatremia in SIADH is primarily the result of excessive water retention caused by a combination of inappropriate antidiuresis and persistent fluid intake in the presence of impaired osmoregulated inhibition of thirst. It is sometimes aggravated by a sodium deficiency caused by a decreased intake or a secondary natriuresis in response to elevated extracellular volume. Inappropriate antidiuresis usually results from endogenous production of AVP that can be either ectopic (from a malignancy) or eutopic (from the hypothalamus/neurohypophysis). Regardless of its origin, different types of osmotic dysregulation of AVP have been reported with possibly fundamental deviations in treatment need and efficacy. A recent quantitative analysis of 50 patients with SIADH, which underwent serial measurements of copeptin during hypertonic saline infusion, revealed five distinct types of osmoregulatory defect ("type A to E") without affiliation to specific underlying diseases. In addition to apparently impaired osmoregulated inhibition of AVP release in the majority of patients, 12% of patients showed an AVP-independent mechanism of inappropriate antidiuresis, whilst 20% of them presented a reverse relation between hormone release and serum osmolality, presumably related to interrupted nonosmotic inhibitory pathways. The interference of these different types of SIAD with clinical presentation and therapy response will be a relevant subject for future research.

Vasopressin receptor antagonists: Characteristics and clinical role

Hyponatremia, the most common electrolyte disorder in hospitalized patients is associated with increased risk of mortality even when mild and apparently asymptomatic. Likewise morbidity manifested as attention deficits, gait disturbances, falls, fractures, and osteoporosis is more prevalent in hyponatremic subjects. Hyponatremia also generates a significant financial burden. Therefore, it is important to explore approaches that effectively and safely treat hyponatremia. Currently available strategies are physiologically sound and affordable but lack evidence from clinical trials and are limited by variable efficacy, slow response, and/or poor compliance. The recent emergence of vasopressin receptor antagonists provides a class of drugs that target the primary pathophysiological mechanism, namely vasopressin mediated impairment of free water excretion. This review summarizes the historical development, pharmacology, clinical trials supporting efficacy and safety, shortcomings, as well as practical suggestions for the use of vasopressin receptor antagonists.

The syndrome of inappropriate antidiuresis (SIAD)

Hyponatraemia is the commonest electrolyte disturbance encountered in clinical practice and the syndrome of inappropriate antidiuresis (SIADH) is the most frequent underlying disorder. There is a well-recognized relationship between hyponatraemia and increased morbidity and mortality, though it is unknown whether SIADH confers the same mortality as other causes of hyponatraemia. SIADH is the biochemical manifestation of a wide variety of diseases, and the pathophysiology of SIADH is sometimes multiple. There have been significant advances in the treatment of SIADH over the last 10 years, in particular since the introduction of the vasopressin-2 receptor antagonists, which provide a potent, disease-specific tool which targets the underlying pathophysiology of SIADH. The mechanisms and the evidence base recommendations of the available therapies for SIADH are discussed in this article. The various guidelines and recommendations for treatment of hyponatraemia all emphasise that fluid restriction is first line therapy for SIADH, but we feel that it is ineffective or unfeasible in many patients. A number of key points relevant to the use of fluid restriction are presented in the manuscript. The clinical efficacy of tolvaptan in SIADH supported by good quality randomized, placebo controlled, clinical trials. However, the cost of the therapy and the need for long term safety data may limit its widespread use. Finally, new recommendations for the management of acute hyponatraemia, with a focus on the use of bolus therapy with 3% hypertonic sodium chloride is described.

Hyponatremia in children with tuberculous meningitis: A hospital-based cohort study

Background:

Hyponatremia has long been recognized as a potentially serious metabolic consequence of tuberculous meningitis (TBM) occurring in 35–65% of children with the disease. The syndrome of inappropriate antidiuretic hormone (SIADH) secretion has for long been believed to be responsible for the majority of cases of hyponatremia in TBM. Cerebral salt wasting syndrome (CSWS) is being increasingly reported as a cause of hyponatremia in some of these children.

Aim:

This study was done to determine the frequency and causes of hyponatremia in children with TBM.

Methods:

Children with newly diagnosed TBM admitted over a 2-year period (January 2009 to December 2010) were included. All patients received anti-tubercular therapy, mannitol for cerebral edema, and steroids. Patients were monitored for body weight, urine output, signs of dehydration, serum electrolytes, blood urea nitrogen, serum creatinine, and urinary sodium. Hyponatremia was diagnosed if the serum sodium was <135 mEq/L. CSWS was diagnosed if there was evidence of excessive urine output, volume depletion, and natriuresis in the presence of hyponatremia. The outcome in terms of survival or death was recorded.

Results:

Twenty-nine of 75 children (38.7%) with TBM developed hyponatremia during their hospital stay. In 19 patients, hyponatremia subsided after the discontinuation of mannitol. Ten patients with persistent hyponatremia had CSWS. There were no patients with SIADH.

Conclusions:

CSWS is an important cause of hyponatremia in children with newly diagnosed TBM. In our patients, it was more commonly seen than SIADH.

Efficacy of conivaptan and hypertonic (3%) saline in treating hyponatremia due to syndrome of inappropriate antidiuretic hormone in a tertiary Intensive Care Unit

Background:

Hyponatremia is one of the most common electrolyte abnormalities encountered in clinical practice and has a significant impact on morbidity and mortality in hospitalized patients. The optimal management of hyponatremia is still evolving. Over the last decade, vaptans have been increasingly used in clinical practice with promising results.

Materials and Methods:

The study included eighty patients with symptomatic hyponatremia due to syndrome of inappropriate antidiuretic hormone (SIADH) admitted and treated in Intensive Care Unit (ICU) with either conivaptan or hypertonic (3%) saline. They were compared for time taken to achieve normal serum sodium, length of ICU and hospital stay, and adverse effects.

Results:

The demographic data and serum sodium levels at admission were comparable between the two groups. After initiating correction, sodium levels at 6, 12, and 24 h were similar between the two groups. However, at 48 h, patients in the conivaptan group (Group C) had higher sodium levels (133.0 ± 3.8 mEq/L) as compared to hypertonic saline group (Group HS) (128.9 ± 2.6 mEq/L), which was statistically significant (P < 0.001). The length of ICU stay was less in the Group C (3.35 ± 0.89 days) when compared with the Group HS (4.61 ± 0.91 days) (P < 0.001). There was no significant difference in mortality between the two groups.

Conclusion:

In patients with symptomatic hyponatremia due to SIADH, conivaptan with its aquaresis property can achieve a significantly better sodium correction, resulting in reduced ICU and hospital stay with no significant adverse effects.

Hyponatremia in Neurotrauma: The Role of Vasopressin

Hyponatremia is frequent in patients suffering from traumatic brain injury, subarachnoid hemorrhage, or following intracranial procedures, with approximately 20% having a decreased serum sodium concentration to <125 mmol/L. The pathophysiology of hyponatremia in neurotrauma is not completely understood, but in large part is explained by the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). The abnormal water and/or sodium handling creates an osmotic gradient promoting the shift of water into brain cells, thereby worsening cerebral edema and precipitating neurological deterioration. Unless hyponatremia is corrected promptly and effectively, morbidity and mortality increases through seizures, elevations in intracranial pressure, and/or herniation. The excess mortality in patients with severe hyponatremia (<125 mmol/L) extends beyond the time frame of hospital admission, with a reported mortality of 20% in hospital and 45% within 6 months of follow-up. Current options for the management of hyponatremia include fluid restriction, hypertonic saline, mineralocorticoids, and osmotic diuretics. However, the recent development of vasopressin receptor antagonists provides a more physiological tool for the management of excess water retention and consequent hyponatremia, such as occurs in SIADH. This review summarizes the existing literature on the pathophysiology, clinical features, and management of hyponatremia in the setting of neurotrauma.

The syndrome of inappropriate antidiuretic hormone secretion: Distribution and characterization according to etiologies

PURPOSE

To determine the distribution of etiologies for the syndrome of inappropriate antidiuretic hormone secretion (SIADH) in hospitalized patients and to characterize patients according to the different etiologies.

METHODS

A single-center retrospective study including all patients diagnosed with SIADH in a large community hospital and tertiary center between 1.1.2007 and 1.1.2013. Two physicians reviewed every patient's medical file for predetermined relevant clinical data.

RESULTS

The study cohort included 555 patients. The most common etiologies were malignancies and medication-induced SIADH, followed by idiopathic SIADH, pulmonary infections, pain and nausea, and central nervous system (CNS) disorders. Subgroup analysis according to etiology showed that CNS disorders were associated with more severe episodes of SIADH. Patients with idiopathic SIADH were older than patients with a specific diagnosis, had a lower urine osmolality, and required less treatment with hypertonic saline. Long-term survival was determined primarily by SIADH etiology rather than hyponatremia severity, with hazard ratios for death of up to 7.31 (95% CI 4.93-10.82, p<0.001) for patients with malignancy-associated SIADH as compared to patients with idiopathic SIADH. Hyponatremia grade at short-term follow-up was also predictive for long-term survival (HR 1.42 per grade, 95% CI 1.21-1.66, p<0.001).

CONCLUSIONS

Patients with SIADH have different characteristics and a different prognosis according to SIADH etiology. Serum sodium concentration at short-term follow-up is predictive of long-term survival. These findings might have diagnostic and treatment-related implications.

Hyponatremia in the intensive care unit: How to avoid a Zugzwang situation?

Hyponatremia is a common electrolyte derangement in the setting of the intensive care unit. Life-threatening neurological complications may arise not only in case of a severe (<120 mmol/L) and acute fall of plasma sodium levels, but may also stem from overly rapid correction of hyponatremia. Additionally, even mild hyponatremia carries a poor short-term and long-term prognosis across a wide range of conditions. Its multifaceted and intricate physiopathology may seem deterring at first glance, yet a careful multi-step diagnostic approach may easily unravel the underlying mechanisms and enable physicians to adopt the adequate measures at the patient’s bedside. Unless hyponatremia is associated with obvious extracellular fluid volume increase such as in heart failure or cirrhosis, hypertonic saline therapy is the cornerstone of the therapeutic of profound or severely symptomatic hyponatremia. When overcorrection of hyponatremia occurs, recent data indicate that re-lowering of plasma sodium levels through the infusion of hypotonic fluids and the cautious use of desmopressin acetate represent a reasonable strategy. New therapeutic options have recently emerged, foremost among these being vaptans, but their use in the setting of the intensive care unit remains to be clarified.

Fatal water intoxication and cardiac arrest in runners during marathons: prevention and treatment based on validated clinical paradigms

Cerebral edema due to exercise-associated hyponatremia and cardiac arrest due to atherosclerotic heart disease cause rare marathon-related fatalities in young female and middle-aged male runners, respectively. Studies in asymptomatic middle-aged male physician-runners during races identified inflammation due to skeletal muscle injury after glycogen depletion as the shared underlying cause. Nonosmotic secretion of arginine vasopressin as a neuroendocrine stress response to rhabdomyolysis mediates hyponatremia as a variant of the syndrome of inappropriate antidiuretic hormone secretion. Fatal hyponatremic encephalopathy in young female runners was curtailed using emergent infusion of intravenous hypertonic (3%) saline to reverse cerebral edema on the basis of this paradigm. This treatment was arrived at through a consensus process within the medical community. An increasing frequency of cardiac arrest and sudden death has been identified in middle-aged male runners in 2 studies since the year 2000. Same-aged asymptomatic male physician-runners showed post-race elevations in interleukin-6 and C-reactive protein, biomarkers that predict acute cardiac events in healthy persons. Hypercoagulability with in vivo platelet activation and release of cardiac troponin and N-terminal pro-brain natriuretic peptide were also observed post-race in these same subjects. High short-term risk for atherothrombosis during races as shown by stratification of biomarkers in asymptomatic men may render nonobstructive coronary atherosclerotic plaques vulnerable to rupture. Pre-race aspirin use in this high-risk subgroup is prudent according to conclusive evidence for preventing first acute myocardial infarctions in same-aged healthy male physicians. On the basis of validated clinical paradigms, taking a low-dose aspirin before a marathon and drinking to thirst during the race may avert preventable deaths in susceptible runners.

Randomized, double blinded, placebo-controlled trial to evaluate the efficacy and safety of tolvaptan in Chinese patients with hyponatremia caused by SIADH

To study the effect of tolvaptan on non-acute, non-hypovolemic hyponatremia in inappropriate secretion of antidiuretic hormone (SIADH) syndrome in Chinese patients. Hyponatremic SIADH patients received placebo (N = 18) or tolvaptan (N = 19) at an initial dose of 15 mg/day with further titration to 30 mg/day and 60 mg/day based on serum sodium concentrations. Randomized, double-blind, placebo-controlled trial. Primary endpoint was the change of the serum sodium from baseline to days 4 and 7. Analysis of covariance (ANCOVA) was used for statistical analysis. At day 4, average daily changes in serum sodium levels from baseline was 1.9 ± 2.9 mmol/L (1.9 ± 2.9 mEq/L) in the placebo group and 8.1 ± 3.6 mmol/L (8.1 ± 3.6 mEq/L) in the tolvaptan group; at day 7, the values were 2.5 ± 3.9 mmol/L (2.5 ± 3.9 mEq/L) and 8.6 ± 3.9 mmol/L (8.6 ± 3.9 mmEq/L) for the placebo and tolvaptan groups (ANCOVA, P < 0.001). At days 4 and 7, daily urine output and proportions of patients with normalized serum sodium were significantly superior in the tolvaptan group. The most common adverse events occurring in the tolvaptan group were dry mouth and thirst. Tolvaptan demonstrated superiority to placebo in the treatment of Chinese SIADH patients with hyponatremia by elevating serum sodium concentration with acceptable safety profile.

Hyponatremia secondary to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH): therapeutic decision-making in real-life cases

Despite being the most common electrolyte disturbance encountered in clinical practice, the diagnosis and treatment of hyponatremia (defined as a serum sodium concentration <135 mmol/L) remains far from optimal. This is extremely troubling because not only is hyponatremia associated with increased morbidity, length of hospital stay and hospital resource use, but it has also been shown to be associated with increased mortality. The reasons for this poor management may partly lie in the heterogeneous nature of the disorder; hyponatremia presents with a variety of possible etiologies, differing symptomology and fluid volume status, thereby making its diagnosis potentially complex. In addition, a general lack of awareness of the clinical impact of the disorder, a fear of adverse outcomes through overcorrection of sodium levels, and a lack of effective targeted treatments until recent years, may all have contributed to a reticence to actively treat cases of hyponatremia. There is therefore a clear unmet need to further educate physicians on the pathophysiology, diagnosis and management of this important condition. Through the use of a variety of real-world cases of patients with hyponatremia secondary to the syndrome of inappropriate secretion of antidiuretic hormone—a condition that accounts for approximately one-third of all cases of hyponatremia—this supplement aims to provide a comprehensive overview of the challenges faced in diagnosing and managing hyponatremia. These cases will also help to illustrate how some of the limitations of traditional therapies may be overcome with the use of vasopressin receptor antagonists.

Hyponatraemia--SIADH in lung cancer diagnostic and treatment algorithms

Lung cancer, in particular small cell lung cancer (SCLC), is a very aggressive solid tumour with limited therapeutic options to date. The majority of patients present, at the time of diagnosis, with extensive disease patterns and reduced performance status. Hyponatraemia is a common finding in SCLC (25%) which can be assigned to a paraneoplastic syndrome termed syndrome of inappropriate ADH secretion (SIADH) in 60% of cases. Hyponatraemia may cause significant and even dramatic neurocognitive deficits, if not treated in an effective manner. Palliative chemo- or radiotherapy is restricted to patients with good performance status and therapeutic adherence. Acute or persistent hyponatraemia may interfere with such treatment options and compromise outcome. This review integrates new diagnostic and therapeutic guidelines to improve the understanding how and when to treat hyponatraemia in thoracic oncology patients Integrating early palliative care in lung cancer patients has a significant impact on prognosis. Correcting hyponatraemia in a supportive and risk stratified fashion may help to improve both prognosis and quality of life and should be a standard in modern palliative care for patients with lung cancer.

Current treatment practice and outcomes. Report of the hyponatremia registry

Current management practices for hyponatremia (HN) are incompletely understood. The HN Registry has recorded diagnostic measures, utilization, efficacy, and outcomes of therapy for eu- or hypervolemic HN. To better understand current practices, we analyzed data from 3087 adjudicated adult patients in the registry with serum sodium concentration of 130 mEq/l or less from 225 sites in the United States and European Union. Common initial monotherapy treatments were fluid restriction (35%), administration of isotonic (15%) or hypertonic saline (2%), and tolvaptan (5%); 17% received no active agent. Median (interquartile range) mEq/l serum sodium increases during the first day were as follows: no treatment, 1.0 (0.0–4.0); fluid restriction, 2.0 (0.0–4.0); isotonic saline, 3.0 (0.0–5.0); hypertonic saline, 5.0 (1.0–9.0); and tolvaptan, 4.0 (2.0–9.0). Adjusting for initial serum sodium concentration with logistic regression, the relative likelihoods for correction by 5 mEq/l or more (referent, fluid restriction) were 1.60 for hypertonic saline and 2.55 for tolvaptan. At discharge, serum sodium concentration was under 135 mEq/l in 78% of patients and 130 mEq/l or less in 49%. Overly rapid correction occurred in 7.9%. Thus, initial HN treatment often uses maneuvers of limited efficacy. Despite an association with poor outcomes and availability of effective therapy, most patients with HN are discharged from hospital still hyponatremic. Studies to assess short- and long-term benefits of correction of HN with effective therapies are needed.

Syndrome of inappropriate anti-diuretic hormone secondary to non-cirrhotic primary hepatocellular carcinoma

Patient: Male, 71

Final Diagnosis: SIADH

Symptoms: Cachexia • confusion

Medication: —

Clinical Procedure: Percutaneous liver biopsy

Specialty: Oncology

Syndrome of inappropriate antidiuretic hormone secretion and cerebral/renal salt wasting syndrome: similarities and differences

Hyponatremia (sodium levels of <135 mEq/L) is one of the most common electrolyte imbalances in clinical practice, especially in patients with neurologic diseases. Hyponatremia can cause cerebral edema and brain herniation; therefore, prompt diagnosis and proper treatment is important in preventing morbidity and mortality. Among various causes of hyponatremia, diagnosing syndrome of inappropriate antidiuretic hormone secretion (SIADH) and cerebral/renal salt wasting syndrome (C/RSW) is difficult due to many similarities. SIADH is caused by excess of renal water reabsorption through inappropriate antidiuretic hormone secretion, and fluid restriction is the treatment of choice. On the other hand, C/RSW is caused by natriuresis, which is followed by volume depletion and negative sodium balance and replacement of water and sodium is the mainstay of treatment. Determinating volume status in hyponatremic patients is the key point in differential between SIADH and C/RSW. However, in most situations, differential diagnosis of these two diseases is difficult because they overlap in many clinical and laboratory aspects, especially to assess differences in volume status of these patients. Although distinction between the SIADH and C/RSW is difficult, improvement of hypouricemia and an increased fractional excretion of uric acid after the correction of hyponatremia in SIADH, not in C/RSW, may be one of the helpful points in discriminating the two diseases. In this review, we compare these two diseases regarding the pathophysiologic mechanisms, diagnosis, and therapeutic point of view.

Hyponatremia: A Review

Hyponatremia is the most frequently occurring electrolyte abnormality and can lead to life-threatening complications. This disorder may be present on admission to the intensive care setting or develop during hospitalization as a result of treatment or multiple comorbidities. Patients with acute hyponatremia or symptomatic chronic hyponatremia will likely require treatment in the intensive care unit (ICU). Immediate treatment with hypertonic saline is needed to reduce the risk of permanent neurologic injury. Chronic hyponatremia should be corrected at a rate sufficient to reduce symptoms but not at an excessive rate that would create a risk of osmotic injury. Determination of the etiology of chronic hyponatremia requires analysis of serum osmolality, volume status, and urine osmolality and sodium level. Correct diagnosis points to the appropriate treatment and helps identify risk factors for accelerated correction of the serum sodium level. Management in the ICU facilitates frequent laboratory draws and allows close monitoring of the patient's mentation as well as quantification of urine output. Overly aggressive correction of serum sodium levels can result in neurological injury caused by osmotic demyelination. Therapeutic measures to lower the serum sodium level should be undertaken if the rate increases too rapidly.

Hyponatremia due to Severe Primary Hypothyroidism in an Infant

Hyponatremia has been reported in the elderly with hypothyroidism and myxedema, but this has not been a universal finding in clinical studies and there have been only a few reports in children. We report a case of an infant who developed hyponatremia due to severe primary hypothyroidism. A 4-month-old ex-preterm male, who had been euthyroid on the newborn screen, developed unexplained hospital-acquired hyponatremia (serum Na 124 mEq/L) while on full oral feeds. He was euvolemic, appeared well and was without myxedema. An evaluation of hyponatremia was negative with the exception of severe primary hypothyroidism (TSH 315.4 IU/mL, repeat 540 IU/mL). The hyponatremia resolved with thyroxine supplementation. This case demonstrates that severe hypothyroidism can result in hyponatremia in infants. It is critical to consider hypothyroidism in the evaluation of an infant with unexplained hyponatremia as untreated hypothyroidism can lead to profound developmental delays.

Differentiating SIADH from Cerebral/Renal Salt Wasting: Failure of the Volume Approach and Need for a New Approach to Hyponatremia

Hyponatremia is the most common electrolyte abnormality. Its diagnostic and therapeutic approaches are in a state of flux. It is evident that hyponatremic patients are symptomatic with a potential for serious consequences at sodium levels that were once considered trivial. The recommendation to treat virtually all hyponatremics exposes the need to resolve the diagnostic and therapeutic dilemma of deciding whether to water restrict a patient with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) or administer salt and water to a renal salt waster. In this review, we briefly discuss the pathophysiology of SIADH and renal salt wasting (RSW), and the difficulty in differentiating SIADH from RSW, and review the origin of the perceived rarity of RSW, as well as the value of determining fractional excretion of urate (FEurate) in differentiating both syndromes, the high prevalence of RSW which highlights the inadequacy of the volume approach to hyponatremia, the importance of changing cerebral salt wasting to RSW, and the proposal to eliminate reset osmostat as a subtype of SIADH, and finally propose a new algorithm to replace the outmoded volume approach by highlighting FEurate. This algorithm eliminates the need to assess the volume status with less reliance on determining urine sodium concentration, plasma renin, aldosterone and atrial/brain natriuretic peptide or the BUN to creatinine ratio.

Hyponatremia: A practical approach

Hyponatremia is an important and common clinical problem. The etiology is multifactorial. Hyponatremia may be euvolemic, hypovolemic or hypervolemic. Proper interpretation of the various laboratory tests helps to differentiate the various types of hyponatremia. Treatment varies with the nature of onset -acute or chronic, severity and symptoms. Normal saline forms the mainstay of treatment for hypovolemic hyponatremia while 3% NaCl and fluid restriction are important for euvolemic hyponatremia. Hypervolemic hyponatremia responds well to fluid restriction and diuretics. There have been several recent advances in the last year with revision in the guidelines for treatment and availability of vaptans. Judicious use of vaptans may help in treatment of hyponatremia.

Masking of syndrome of inappropriate antidiuretic hormone secretion: the isonatremic syndrome

OBJECTIVE

To determine whether the administration of isotonic saline in patients undergoing spinal fusion surgery prevents the development of hyponatremia, thus masking the detection of syndrome of inappropriate antidiuretic hormone secretion (SIADH).

STUDY DESIGN

Prospective observational cohort study conducted in pediatric patients undergoing spinal fusion surgery. Using established criteria for diagnosing SIADH with the exception of serum sodium as a criterion, we separated patients into those with and without masked SIADH. Random cortisol levels were measured in the perioperative period to test for adrenal insufficiency to exclude it as a cause for natriuresis and hyponatremia.

RESULTS

Of the 40 patients included in the study, 13 (32%; 95% CI, 19%-49%) met study criteria for masked SIADH. The serum sodium levels between the 2 groups were not different throughout the postoperative period. The antidiuretic hormone levels were increased at 24-48 hours after surgery (20.4 pg/mL in masked SIADH group vs 6.6 pg/mL in no masked SIADH group, P = .04). Subjects with masked SIADH demonstrated a tendency for weight gain (3.9 kg vs 2.5 kg, P = .058), which was maximal on postoperative day 2. Cortisol levels were similar between the groups.

CONCLUSION

Masked SIADH (SIADH-like state without hyponatremia) commonly occurs in the postoperative period in children and young adults undergoing spinal fusion surgery. Early postoperative evaluation and recognition may result in appropriate management of patient's fluid balance.

Recovery from SIADH-associated osteoporosis: a case report

INTRODUCTION

Recent studies show an association between hyponatremia and osteoporosis. We have previously reported a case of severe male osteoporosis due to chronic syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Here, we provide a follow-up on this case after cure of the condition that further supports the causal relationship.

THE CASE

A 38-year-old man had been diagnosed with severe osteoporosis most likely due to chronic SIADH. The SIADH was believed to be idiopathic. A magnetic resonance imaging scan, however, revealed a tumor in the sinus, and biopsies showed an esthesioneuroblastoma, immunohistochemically positive for antidiuretic hormone (ADH). After the tumor was removed, ADH and sodium levels normalized. A dual-energy x-ray absorptiometry scan performed 7 months after the patient's last surgery showed a significant spontaneous improvement in bone mineral density in the lumbar vertebrae.

CONCLUSION

This case provides evidence for a causal relationship between SIADH and chronic hyponatremia and impaired bone metabolism that can lead to severe secondary osteoporosis. The effect on bone metabolism is at least partially reversible.

Management of hyponatremia in various clinical situations

OPINION STATEMENT

Hyponatremia is the most common electrolyte abnormality in both inpatient and outpatient settings. The condition primarily results from the combination of impaired free water excretion due to elevated vasopressin levels in conjunction with a source of free water intake. Recent studies have revealed that even mild and asymptomatic hyponatremia is associated with deleterious consequences. It is an independent risk factor for mortality and is also associated with increased length of hospitalization and hospital costs. Even mild chronic hyponatremia can result in subtle neurologic impairment and bone demineralization, leading to falls and associated bone fractures in the elderly. Hyponatremia can be a difficult condition to treat, with varying therapeutic strategies based on the etiology, severity, duration, and extent of neurologic symptoms. The ideal magnitude of correction is also controversial, as both inadequate therapy and overly aggressive therapy can result in neurologic injury. Formulas that have been devised to aid in the treatment of hyponatremia can be inaccurate in that they fail to adequately account for the renal response to therapy. Hyponatremic encephalopathy is the most serious complication of hyponatremia, and can result in permanent neurologic impairment or death if left untreated. Individuals most at risk for developing hyponatremic encephalopathy are postmenarchal women, children under 16 years of age, patients with central nervous system disease or hypoxemia, and patients in the postoperative setting. The preferred therapy for hyponatremic encephalopathy is a 100-ml bolus of 3 % sodium chloride (513 mEq/L) administered in repeated doses until symptoms reverse, with the goal of increasing the serum sodium 5-6 mEq/L. Vasopressin (V2) antagonists (vaptans) are not appropriate for the management of acute hyponatremic encephalopathy, as the onset of action is not sufficiently rapid and the increase in sodium is not predictable. Vaptans are primarily indicated for the treatment of asymptomatic hyponatremia due to SIAD that is refractory to conventional measures.

Review and analysis of differing regulatory indications and expert panel guidelines for the treatment of hyponatremia

INTRODUCTION AND OBJECTIVE

As evidence grows about the management of hyponatremia, a number of different international and national recommendations/guidelines from professional organizations have recently been published that offer guidance on decision-making. However, they include several important differences that could confuse practising physicians. This article summarizes the key differences in guideline recommendations by various independent groups, taking the marketing authorizations granted by different regulatory agencies into account. It proposes a synthesis of implications for practising physicians as a practical method for resolving these differences as they relate to everyday clinical practice.

METHODS

The authors reviewed all recent guidelines and consensus documents worldwide to assess differences and similarities. They also reviewed licensed indications for therapeutic agents in hyponatremia.

RESULTS

The actual indications for the only pharmacological therapy approved across three continents for the treatment of hyponatremia--the vaptans--differ substantially around the world. The numerous treatment guidelines published to date also fail to achieve agreement on hyponatremia management. The possible reasons for these differences are explored in this paper. The authors emphasize the crucial role that clinical judgment must continue to play in decision-making about the management of hyponatremia in individual patients. Such judgments should take into account appropriate appraisals of evidence by authoritative experts in the field, as well as the decisions of regulatory agencies that have based their approvals on a critical review of the efficacy and safety data for approved treatments for hyponatremia.

CONCLUSION

It is clinical judgment rather than guidelines that should dictate the ultimate choices physicians make for their patients, not only in hyponatremia, but in all aspects of medicine.

Hyponatraemia in elderly and adult psychiatric inpatients

Objectives: The objectives of this paper are to review the presentation of hyponatraemia and diagnose its cause in psychiatric inpatients.

Method: Episodes of significant hyponatraemia (sodium <130mmol/L) were identified from computerised biochemical data and a retrospective review of patients' notes was carried out.

Result. The diagnoses of hyponatraemia reached were different for the two groups of patients studied, adults of over 65 years and under 65 years. Carbamazepine, polydipsia and medical conditions were found as causes in the below 65 age group. Diuretics, medical conditions and lofepramine were identified as causes in the over 65 age group. Inpatients with polydipsia below the age of 65 had lower sodium (p = 0.013) and urea levels (p = 0.00059) than other groups and patients with carbamazepine induced hyponatraemia tended to have episodic hypocalcaemia (p = 0.056). These groups were compared using Fisher's exact test. This study also showed the overall frequency of serum sodium of less than 135mmol/L to be 9.5% in psychiatric inpatients.

Conclusion: Hyponatraemia is a not uncommon finding in psychiatric inpatients. Attention to drug therapy and biochemical findings are helpful in its diagnosis. Accurate diagnosis is usually possible and may vary according to age-group.

Relapsing inappropriate antidiuretic hormone secretion in an anti-aquaporin-4 antibody positive paediatric patient

Paediatric patients with the syndrome of an inappropriate antidiuretic hormone secretion (SIADH), as a manifestation of inflammatory demyelinating disorders of the central nervous system, have been rarely described until now, in only a few cases of neuromyelitis optica spectrum disorders (NMOSDs). We present a case of relapsing SIADH associated with NMOSD, in an anti-aquaporin-4 antibody positive 14-year-old girl, who is, to our best knowledge, the first reported paediatric patient with relapsing SIADH and NMOSD. Additionally, our case further supports the notion that paediatric encephalomyelitis associated with SIADH should suggest the diagnosis of NMOSD.

Amiodarone induced hyponatremia masquerading as syndrome of inappropriate antidiuretic hormone secretion by anaplastic carcinoma of prostate

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is one of the most common causes of hyponatremia. The usual causes are malignancies, central nervous system, pulmonary disorders, and drugs. Amiodarone is a broad spectrum antiarrhythmic agent widely used in the management of arrhythmias. The different side effects include thyroid dysfunction, visual disturbances, pulmonary infiltrates, ataxia, cardiac conduction abnormalities, drug interactions, corneal microdeposits, skin rashes, and gastrointestinal disturbances. SIADH is a rare but lethal side effect of amiodarone. We describe a 62-year-old male who was suffering from advanced prostatic malignancy, taking amiodarone for underlying heart disease. He developed SIADH which was initially thought to be paraneoplastic in etiology, but later histopathology refuted that. This case emphasizes the importance of detailed drug history and the role of immunohistochemistry in establishing the diagnosis and management of hyponatremia due to SIADH.

A copeptin-based classification of the osmoregulatory defects in the syndrome of inappropriate antidiuresis

Hyponatremia, the most frequent electrolyte disorder, is caused predominantly by the syndrome of inappropriate antidiuresis (SIAD). A comprehensive characterization of SIAD subtypes, defined by type of osmotic dysregulation, is lacking, but may aid in predicting therapeutic success. Here, we analyzed serial measurements of serum osmolality and serum sodium, plasma arginine vasopressin (AVP), and plasma copeptin concentrations from 50 patients with hyponatremia who underwent hypertonic saline infusion. A close correlation between copeptin concentrations and serum osmolality existed in 68 healthy controls, with a mean osmotic threshold±SD of 282±4 mOsM/kg H2O. Furthermore, saline-induced changes in copeptin concentrations correlated with changes in AVP concentrations in controls and patients. With use of copeptin concentration as a surrogate measure of AVP concentration, patients with SIAD could be grouped according to osmoregulatory defect: Ten percent of patients had grossly elevated copeptin concentrations independent of serum osmolality (type A); 14% had copeptin concentrations that increased linearly with rising serum osmolality but had abnormally low osmotic thresholds (type B); 44% had normal copeptin concentrations independent of osmolality (type C), and 12% had suppressed copeptin concentrations independent of osmolality (type D). A novel SIAD subtype discovered in 20% of patients was characterized by a linear decrease in copeptin concentrations with increasing serum osmolality (type E or "barostat reset"). In conclusion, a partial or complete loss of AVP osmoregulation occurs in patients with SIAD. Although the mechanisms underlying osmoregulatory defects in individual patients are presumably diverse, we hypothesize that treatment responses and patient outcomes will vary according to SIAD subtype.

Serum-based protein biomarkers for detection of lung cancer

Lung cancer is one of the most common cancers in terms of both incidence and mortality.The major reasons for the increasing number of deaths from lung cancer are late detection and lack of effective therapies. To improve our understanding of lung cancer biology, there is urgent need for blood-based, non-invasive molecular tests to assist in its detection in a cost-effective manner at an early stage when curative interventions are still possible. Recent advances in proteomic technology have provided extensive, high throughput analytical tools for identification, characterization and functional studies of proteomes. Changes in protein expression patterns in response to stimuli can serve as indicators or biomarkers of biological and pathological processes as well as physiological and pharmacological responses to drug treatment, thus aiding in early diagnosis and prognosis of disease. However, only a few biomarkers have been approved by the FDA to date for screening and diagnostic purposes. This review provides a brief overview of currently available proteomic techniques, their applications and limitations and the current state of knowledge about important serum biomarkers in lung cancer and their potential value as prognostic and diagnostic tools.

Clinical evaluation of hyponatremia and hypovolemia in critically ill adult neurologic patients: contribution of the use of cumulative balance of sodium

PURPOSE

Knowledge of the cumulative balance of sodium (CBS) is important for the diagnosis of salt disorders and water homeostasis and has the potential to predict hypovolemic status in acute neurological patients. However, an extensive application of the use of CBS is still lacking in the intensive care setting, where salt and water homeostasis represents a priority.

METHODS

Records of consecutive series of acute neurological patients admitted to a neurointensive care unit over a 6-month period were retrospectively reviewed. CBS was calculated at the admission to the Emergency Department. Discrimination between cerebral salt-wasting syndrome (CSWS) and the syndrome of inappropriate antidiuretic hormone secretion (SIADH) was performed on the basis of the classical criteria. Additionally, we used the findings of a negative CBS exceeding 2 mEq/kg for the diagnosis of CSWS. Two independent clinicians who were blinded to the CBS results performed diagnosis of the causes of hyponatremia and estimated the daily volemic status of the patients on the basis of clinical parameters. Logistic regression analysis was used to determine the independent prognostic factors of hypovolemia.

RESULTS

Thirty-five patients were studied for a total of 418 days. Four patients (11.4%) fitted the criteria of CSWS and three patients (8.5%) had SIADH. The unavailability of the CBS led to a wrong diagnosis in three of the eight hyponatremic patients (37.5%). The risk of developing hypovolemia in patients with negative CBS was 7.1 times higher (CI 3.86-13.06; p < 0.001). Multivariate analysis revealed that negative cumulative fluid balance, negative CBS >2 mEq/kg, and CVP ≤5 cmH2O were independent prognostic factors for hypovolemia.

CONCLUSIONS

CBS is likely to be a useful parameter in the diagnosis of CSWS and a surrogate parameter for estimating hypovolemia in acute neurological patients.

Clinical analysis of brain trauma-associated SIADH

The objective of this study was to analyze the clinical features of brain trauma associated syndrome of inappropriate antidiuretic hormone secretion. A retrospective analysis was performed for the electrolytes and osmolality of blood and urine samples of brain injury patients, which have been collected in our department since last 20 years. Four cases of brain injury patients met the criteria of SIADH, and three of them were cured but one patient died. In conclusion, the pathogenesis and treatment of SIADH associated with brain injury are different from hyponatremia. Early diagnosis and treatment can reduce the morbidity and mortality of patients with traumatic brain injury.

Codeine-induced syndrome of inappropriate antidiuretic hormone: case report

BACKGROUND

The syndrome of inappropriate antidiuretic hormone was first described in 1957 by Schwartz, and is characterised by hyponatraemia, inappropriately increased urine osmolality and urine sodium, and decreased serum osmolality in a euvolemic patient without edema. A patient with the syndrome of inappropriate antidiuretic hormone should have normal cardiac, renal, adrenal, hepatic, and thyroid functions and should not take any diuretics.

CASE REPORT

We present a case of the syndrome of inappropriate antidiuretic hormone caused by codeine and associated with reduced urine volume, increased urine sodium, and decreased serum sodium concentration.

CONCLUSION

The syndrome of inappropriate antidiuretic hormone is a disease that can lead to morbidity and even mortality. Clinicians should measure serum electrolytes intermittently in order to avoid missing the diagnosis of the syndrome of inappropriate antidiuretic hormone in patients using opioid.

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.

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. Hyponatraemia is present in 15-20% of emergency admissions to hospital and occurs in up to 20% of critically ill patients. Symptomatology may vary from subtle to severe or even life threatening. Despite this, the management of patients remains problematic. Against this background, the European Society of Intensive Care Medicine, the European Society of Endocrinology and the European Renal Association-European Dialysis and Transplant Association, represented by European Renal Best Practice have developed a 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.

Prompt efficacy of tolvaptan in treating hyponatremia of syndrome of inappropriate secretion of antidiuretic hormone (SIADH) closely associated with rupture of a gastric artery aneurysm

A 78-year-old man with abdominal pain was diagnosed with a rupture of a gastric artery aneurysm. The serum Na level promptly decreased from 135 to 110 mmol/L within several days. Brain magnetic resonance angiography revealed severe vasoconstriction of the cerebral basilar artery and anterior cerebral artery. There was neither dehydration nor edema. The plasma arginine vasopressin level was 3.3 pg/mL, despite hypoosmolality. These findings indicated a diagnosis of syndrome of inappropriate secretion of antidiuretic hormone (SIADH) derived from severe vasoconstriction of the cerebral arteries. The administration of 7.5 mg of tolvaptan rapidly increased the serum Na level from 123 to 138 mmol/L within the first 24 hours, thereafter continuously maintaining a normal level. Treatment with tolvaptan corrected the patient's dilutional hyponatremia.