Clinical practice. The syndrome of inappropriate antidiuresis

Syndrome of inappropriate antidiuretic hormone associated with eosinophilic granulomatosis and polyangiitis

A 62-year-old man presented with classic signs and symptoms of eosinophilic granulomatosis and polyangiitis (EGPA, also known as Churg-Strauss syndrome)-mononeuritis multiplex, palpable purpura, hypereosinophilia, positive P-ANCA (perinuclear anti-neutrophil cytoplasmic antibodies) developed diffuse alveolar haemorrhage. The patient had longstanding mild hyponatraemia, but developed moderate and symptomatic hyponatraemia characteristic of the syndrome of inappropriate antidiuretic hormone. The patient's serum sodium returned to his baseline- mildly hyponatraemic, after initiation of treatment targeted towards EGPA.

Efficacy of Furosemide, Oral Sodium Chloride, and Fluid Restriction for Treatment of Syndrome of Inappropriate Antidiuresis (SIAD): An Open-label Randomized Controlled Study (The EFFUSE-FLUID Trial)

RATIONALE & OBJECTIVE

First-line therapy for syndrome of inappropriate antidiuresis (SIAD) is fluid restriction. Additional treatment for patients who do not respond to fluid restriction are water restriction with furosemide or water restriction with furosemide and salt supplementation. However, the efficacy of these treatments has never been tested in a randomized controlled study. The objective of this study was to investigate whether, combined with fluid restriction, furosemide with or without sodium chloride (NaCl) supplementation was more effective than fluid restriction alone in the treatment of hyponatremia in SIAD.

STUDY DESIGN

Open-label randomized controlled study.

SETTING & PARTICIPANTS

Patients with serum sodium concentrations ([Na⁺]) ≤ 130mmol/L due to SIAD.

INTERVENTION(S)

Random assignment to 1 of 3 groups: fluid restriction alone (FR), fluid restriction and furosemide (FR+FM), or fluid restriction, furosemide, and NaCl (FR+FM+NaCl). Strictness of fluid restriction (<1,000 or<500mL/d) was guided by the urine to serum electrolyte ratio. Furosemide dosage was 20 to 40mg/d. NaCl supplements were 3g/d. All treatments were continued for 28 days.

OUTCOMES

The primary outcome was change in [Na⁺] at days 4, 7, 14, and 28 after randomization.

RESULTS

92 patients were recruited (FR, n=31; FR+FM, n=30; FR+FM+NaCl, n=31). Baseline [Na⁺] was 125±4mmol/L, and there were no significant differences between groups. Mean [Na⁺] on day 4 in all treatment groups was significantly increased from baseline by 5mmol/L (P<0.001); however, the change in [Na⁺] was not significantly different across groups (P=0.7). There was no significant difference in percentage of patients or time to reach [Na⁺] ≥ 130 or≥135mmol/L across the 3 groups. Acute kidney injury and hypokalemia (potassium≤3.0mmol/L) were more common in patients receiving furosemide.

LIMITATIONS

Open-label treatment.

CONCLUSIONS

In patients with SIAD, furosemide with NaCl supplement in combination with fluid restriction did not show benefits in correction of [Na⁺] compared with treatment with fluid restriction alone. Incidences of acute kidney injury and hypokalemia were increased in patients receiving furosemide.

FUNDING

None.

TRIAL REGISTRATION

Registered at the Thai Clinical Trial Registry with study number TCTR20170629004.

Low-dose Quetiapine-induced Syndrome of Inappropriate Antidiuretic Hormone in a Patient with Traumatic Brain Syndrome

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is characterized by hyponatremia, low serum osmolality, and clinical euvolemia in the absence of diuretic medication. And the causes of SIADH are various, antipsychotic agents and traumatic brain injury (TBI) are well known. Quetiapine is often chosen to manage the maladaptive behavior of patients with post-TBI. Although a previous study reported that quetiapine doses ranging from 25 to 300 mg were effective and tolerable, the symptoms of the patient might be aggravated. The symptoms of TBI such as nausea, malaise, headache, lethargy, and mild cognitive deficits are similar to those of SIADH. So the differentiation between SIADH and TBI may be difficult. This paper reports a case of SIADH in a patient with a TBI after using a small dose of 25 to 50 mg quetiapine.

A Randomized Trial of Empagliflozin to Increase Plasma Sodium Levels in Patients with the Syndrome of Inappropriate Antidiuresis

BACKGROUND

Treatment options to address the hyponatremia induced by the syndrome of inappropriate antidiuresis (SIAD) are inadequate. The sodium glucose cotransporter 2 (SGLT2) inhibitor empagliflozin promotes osmotic diuresis via urinary glucose excretion and therefore, might offer a novel treatment option for SIAD.

METHODS

In this double-blind, randomized trial, we recruited 88 hospitalized patients with SIAD-induced hyponatremia <130 mmol/L at the University Hospital Basel from September 2016 until January 2019 and assigned patients to receive, in addition to standard fluid restriction of <1000 ml/24 h, a once-daily dose of oral empagliflozin or placebo for 4 days. The primary end point was the absolute change in plasma sodium concentration after 4 days of treatment. Secondary end points included predisposing factors for treatment response and safety of the intervention.

RESULTS

Of the 87 patients who completed the trial, 43 (49%) received treatment with empagliflozin, and 44 (51%) received placebo. Baseline plasma sodium concentrations were similar for the two groups (median 125.5 mmol/L for the empaflozin group and median 126 mmol/L for the placebo group). Patients treated with empagliflozin had a significantly higher increase of median plasma sodium concentration compared with those receiving placebo (10 versus 7 mmol/L, respectively; P=0.04). Profound hyponatremia (<125 mmol/L) and lower baseline osmolality levels increased the likelihood of response to treatment with empagliflozin. Treatment was well tolerated, and no events of hypoglycemia or hypotension occurred among those receiving empagliflozin.

CONCLUSIONS

Among hospitalized patients with SIAD treated with fluid restriction, those who received empagliflozin had a larger increase in plasma sodium levels compared with those who received placebo. This finding indicates that empagliflozin warrants further study as a treatment for the disorder.

Recurrent Severe Hyponatremia in a Patient with Sjögren's Syndrome

Sjögren's syndrome (SS) is an autoimmune disease that presents with exocrine gland dysfunction. Renal involvement is common in SS and often results in tubulointerstitial nephritis, renal tubular acidosis, and Fanconi's syndrome. Electrolyte imbalances are commonly the first symptom of renal involvement of SS. The most common feature of dysnatremia in SS is hypernatremia with diabetes insipidus. However, cases of hyponatremia with syndrome of inappropriate antidiuretic hormone secretion (SIADH) are rarely reported in patients with SS. Herein, we report a case of recurrent severe SIADH in a patient with SS.

Copeptin is not useful as a marker of malignant disease in the syndrome of inappropriate antidiuresis

OBJECTIVE

The syndrome of inappropriate antidiuresis (SIAD) is a common condition in hospitalized patients. It is crucial to establish the cause of SIAD, especially in order to exclude underlying malignancy. As malignant SIAD may be due to a paraneoplastic synthesis of arginine vasopressin, we hypothesized that its stable surrogate marker copeptin can be used as a diagnostic tool to differentiate between malignant and non-malignant SIAD.

METHODS

Prospective observational study. We analyzed data from 146 SIAD patients of two different cohorts from Switzerland and Germany. Patients were included while presenting at the emergency department and underwent a standardized diagnostic assessment including the measurement of copeptin levels.

RESULTS

Thirty-nine patients (median age: 63 years, 51% female) were diagnosed with cancer-related SIAD and 107 (median age: 73 years, 68% female) with non-malignant SIAD. Serum sodium levels were higher in cancer-related versus non-malignant SIAD: median (IQR) 124 mmol/l (120; 127) versus 120 mmol/l (117; 123) (P<0.001). Median (IQR) copeptin levels of patients with cancer-related SIAD were 11.1 pmol/l (5.2; 37.1) and 10.5 pmol/l (5.2; 25.2) with non-malignant SIAD (P = 0.38). Among different cancer entities, patients suffering from small-cell lung cancer showed the highest copeptin values, but overall no significant difference in copeptin levels between cancer types was observed (P = 0.46).

CONCLUSIONS

Copeptin levels are similar in cancer-related and non-malignant SIAD. Therefore, Copeptin does not seem to be suitable as a marker of malignant disease in SIAD.

Hyponatremia Associated with Pulmonary Arterial Hypertension: Syndrome of Inappropriate Antidiuresis Versus Right Heart Failure

Because it is associated with mortality, hyponatremia is an important feature of pulmonary arterial hypertension. Its mechanisms remain unclear, although right heart failure resulting from pulmonary arterial hypertension may lead to systemic congestion and arterial underfilling. However, most patients with pulmonary arterial hypertension are clinically euvolemic and have no peripheral edema. Unlike patients with underlying heart disease, neurohumoral activation is not demonstrated in hyponatremic patients with pulmonary arterial hypertension, who show features of congestive heart failure only at later stages in their disease. Here, a case vignette is introduced, and the pathophysiology of hyponatremia in pulmonary arterial hypertension will be discussed. Syndrome of inappropriate antidiuresis (SIAD) appears to underlie hyponatremia in the initial phase of pulmonary arterial hypertension. The mechanisms by which various lung diseases can lead to SIAD remain an enigma.

Hyponatraemia: the importance of obtaining a detailed history and corroborating point-of-care analysis with laboratory testing

We describe a 67-year-old man admitted from a mental health unit with an incidental finding of hyponatraemia on routine blood tests. Laboratory investigations were in keeping with syndrome of inappropriate antidiuretic hormone secretion (SIADH). He had been recently commenced on mirtazapine. During his inpatient stay, he became increasingly confused. Review of a previous admission with hyponatraemia raised the possibility of voltage-gated potassium channel antibody-associated limbic encephalitis, although subsequent investigations deemed this unlikely as a cause of hyponatraemia. Although his sodium levels improved with fluid restriction, serial point-of-care testing proved misleading in monitoring the efficacy of treatment as inconsistencies were seen in comparison with laboratory testing. The cause of hyponatraemia may have been medication-induced SIADH and/or polydipsia. This case highlights the importance of collating detailed histories and laboratory blood testing to guide management in cases of hyponatraemia of unknown aetiology.

[Hyponatremia-workflow for intensive care physicians]

Hyponatremia (sodium <135 mmol/l) is the most common electrolyte disorder. Despite identical serum concentrations, clinical symptomatology can vary greatly from mild to life-threatening. Accordingly, individual patients require immediate active treatment, while the majority of (mostly oligosymptomatic) patients should first undergo differentiated diagnosis. The most important element is the assessment of the clinical situation of the patient and never isolated laboratory chemical constellations: "Treat the patient, not the numbers".

Syndrome of inappropriate antidiuretic hormone secretion as a side effect of chemotherapy for testicular cancer: A case report

INTRODUCTION

Inappropriate antidiuretic hormone secretion syndrome can be a serious adverse event of cisplatin-based chemotherapy. Cisplatin had to be changed to other drugs or chemotherapy completely discontinued in earlier reported cases.

CASE PRESENTATION

Three cycles of bleomycin, etoposide, and cisplatin chemotherapy were planned for a 40-year-old man with a diagnosis of lymph node recurrence of testicular cancer. On day 9, he suffered from vomiting and mental disturbance. Severe hyponatremia (110 mEq/L) with low plasma osmolality led to a diagnosis of a syndrome of inappropriate antidiuretic hormone secretion, and infusions of hypertonic saline and salt intake were prescribed. Second and third courses of bleomycin, etoposide, and cisplatin chemotherapy could then be given with careful electrolyte management.

CONCLUSION

Continuation of cisplatin administration with precise electrolyte adjustment can be a treatment option in regimens where cisplatin is essential for achieving optimal antitumor efficacy.

Resistant syndrome of inappropriate antidiuretic hormone (SIADH) secondary to atonic bladder in an older woman

Syndrome of inappropriate antidiuretic hormone (SIADH) is the most common cause of hyponatraemia. There are many causes of SIADH, but investigation tends to focus around the most common causes-particularly diseases of the brain and lung, malignancy and medication-induced SIADH [Ellison and Berl (2007, The Syndrome of Inappropriate Antidiuresis. N Engl J Med., 356, 2064-72]. We describe a case of SIADH secondary to atonic bladder in an 83-year old woman, which was discovered on MRI of the abdomen, performed for further characterisation of a known pancreatic lesion. Insertion of a urinary catheter alleviated retention and resulted in prompt resolution of hyponatraemia. This is an under-recognised cause of this common condition, with important implications for investigation and management.

Association between Clinical and Laboratory Markers and 5-year Mortality among Patients with Stroke

Factors influencing long-term stroke mortality have not been comprehensively investigated. This study aimed to identify the baseline clinical, laboratory, demographic/socioeconomic, and hospital factors influencing 5-year mortality in patients with first stroke. Total 3,956 patients with first-stroke hospitalization from 2004 to 2008 were connected to the longitudinal National Health Insurance Research Database. Post-admission baseline data that significantly increased 5-year mortality were red cell distribution width (RDW) >0.145 (adjusted hazard ratio [aHR] = 1.71), hemoglobin <120 g/L (aHR = 1.25), blood sugar <3.89 mmol/L (70 mg/dL)(aHR = 2.57), serum creatinine >112.27 μmol/L (aHR = 1.76), serum sodium <134 mmol/L (aHR = 1.73), body mass index (BMI) < 18.5 kg/m² (aHR = 1.33), Glasgow Coma Scale <15 (aHR = 1.43), Stroke Severity Index ≥20 (aHR = 3.92), Charlson–Deyo Comorbidity Index ≥3 (aHR = 4.21), no rehabilitation (aHR = 1.86), and age ≥65 years (aHR = 2.25). Hemoglobin, RDW, blood sugar, serum creatinine and sodium, BMI, consciousness, stroke severity, comorbidity, rehabilitation, and age were associated with 5-year mortality in patients with first stroke.

Current Diagnosis and Management of Small-Cell Lung Cancer

Small-cell lung cancer (SCLC) is an aggressive disease with distinct pathological, clinical, and molecular characteristics from non-small-cell lung cancer. SCLC has high metastatic potential, resulting in a clinically poor prognosis. Early concurrent chemo-radiation is the standard of care for limited-stage SCLC (LS-SCLC). Prophylactic cranial irradiation (PCI) is recommended for patients with LS-SCLC without progression of disease after initial therapy. A combination of etoposide and cisplatin or carboplatin remains the mainstay of first-line treatment for ES-SCLC, with the addition of atezolizumab, now becoming standard. Most SCLCs initially respond to therapy but almost invariably recur. Topotecan and amrubicin (in Japan) remain the primary chemotherapy options for relapsed SCLC. Immunotherapy, including nivolumab with or without ipilimumab, is now available for refractory disease. In general, the poor prognosis of SCLC has not improved significantly for more than 3 decades. Recently, next-generation molecular profiling studies have identified new therapeutic targets for SCLC. A variety of proapoptotic agents, compounds capitalizing on DNA-repair defects, immunotherapy agents, and antibody-drug conjugates are being evaluated in SCLC, with a number of them showing early promise.

Copeptin and its role in the diagnosis of diabetes insipidus and the syndrome of inappropriate antidiuresis

Copeptin is secreted in an equimolar amount to arginine vasopressin (AVP) but can easily be measured in plasma or serum with a sandwich immunoassay. The main stimuli for copeptin are similar to AVP, that is an increase in osmolality and a decrease in arterial blood volume and pressure. A high correlation between copeptin and AVP has been shown. Accordingly, copeptin mirrors the amount of AVP in the circulation. Copeptin has, therefore, been evaluated as diagnostic biomarker in vasopressin-dependent disorders of body fluid homeostasis. Disorders of body fluid homeostasis are common and can be divided into hyper- and hypoosmolar circumstances: the classical hyperosmolar disorder is diabetes insipidus, while the most common hypoosmolar disorder is the syndrome of inappropriate antidiuresis (SIAD). Copeptin measurement has led to a "revival" of the direct test in the differential diagnosis of diabetes insipidus. Baseline copeptin levels, without prior thirsting, unequivocally identify patients with nephrogenic diabetes insipidus. In contrast, for the difficult differentiation between central diabetes insipidus and primary polydipsia, a stimulated copeptin level of 4.9 pmol/L upon hypertonic saline infusion differentiates these two entities with a high diagnostic accuracy and is clearly superior to the classical water deprivation test. On the contrary, in the SIAD, copeptin measurement is of only little diagnostic value. Copeptin levels widely overlap in patients with hyponatraemia and emphasize the heterogeneity of the disease. Additionally, a variety of factors lead to unspecific copeptin elevations in the acute setting further complicating its interpretation. The broad use of copeptin as diagnostic marker in hyponatraemia and specifically to detect cancer-related disease in SIADH patients can, therefore, not be recommended.

Germline-Derived Gain-of-Function Variants of Gsα-Coding GNAS Gene Identified in Nephrogenic Syndrome of Inappropriate Antidiuresis

BACKGROUND

The stimulatory G-protein α-subunit encoded by GNAS exons 1-13 (GNAS-Gsα) mediates signal transduction of multiple G protein-coupled receptors, including arginine vasopressin receptor 2 (AVPR2). Various germline-derived loss-of-function GNAS-Gsα variants of maternal and paternal origin have been found in pseudohypoparathyroidism type Ia and pseudopseudohypoparathyroidism, respectively. Specific somatic gain-of-function GNAS-Gsα variants have been detected in McCune-Albright syndrome and may result in phosphate wasting. However, no germline-derived gain-of-function variant has been identified, implying that such a variant causes embryonic lethality.

METHODS

We performed whole-exome sequencing in two families with dominantly inherited nephrogenic syndrome of inappropriate antidiuresis (NSIAD) as a salient phenotype after excluding a gain-of-function variant of AVPR2 and functional studies for identified variants.

RESULTS

Whole-exome sequencing revealed two GNAS-Gsα candidate variants for NSIAD: GNAS-Gsα p.(F68_G70del) in one family and GNAS-Gsα p.(M255V) in one family. Both variants were absent from public and in-house databases. Of genes with rare variants, GNAS-Gsα alone was involved in AVPR2 signaling and shared by the families. Protein structural analyses revealed a gain-of-function-compatible conformational property for p.M255V-Gsα, although such assessment was not possible for p.F68_G70del-Gsα. Both variants had gain-of-function effects that were significantly milder than those of McCune-Albright syndrome-specific somatic Gsα variants. Model mice for p.F68_G70del-Gsα showed normal survivability and NSIAD-compatible phenotype, whereas those for p.M255V-Gsα exhibited severe failure to thrive.

CONCLUSIONS

This study shows that germline-derived gain-of-function rare variants of GNAS-Gsα exist and cause NSIAD as a novel Gsα-mediated genetic disease. It is likely that AVPR2 signaling is most sensitive to GNAS-Gsα's gain-of-function effects.

Arginine Vasopressin and Posterior Reversible Encephalopathy Syndrome Pathophysiology: the Missing Link?

Posterior reversible encephalopathy syndrome (PRES) is a clinicoradiological entity characterized by a typical brain edema. Its pathogenesis is still debated through hypoperfusion and hyperperfusion theories, which have many limitations. As PRES occurs almost exclusively in clinical situations with arginine vasopressin (AVP) hypersecretion, such as eclampsia and sepsis, we hypothesize that AVP plays a central pathophysiologic role. In this review, we discuss the genesis of PRES and its symptoms through this novel approach. We theorize that AVP axis stimulation precipitates PRES development through an increase in AVP secretion or AVP receptor density. Activation of vasopressin V_1a receptors leads to cerebral vasoconstriction, causing endothelial dysfunction and cerebral ischemia. This promotes cytotoxic edema through hydromineral transglial flux dysfunction and may increase endothelial permeability, leading to subsequent vasogenic brain edema. If our hypothesis is confirmed, it opens new perspectives for better patient monitoring and therapies targeting the AVP axis in PRES.

Antibody-LGI 1 autoimmune encephalitis manifesting as rapidly progressive dementia and hyponatremia: a case report and literature review

BACKGROUND

Anti leucine-rich glioma inactivated 1 (LGI1) encephalitis is a rare autoimmune encephalitis (AE), characterized by acute or subacute cognitive impairment, faciobrachial dystonic seizures, psychiatric disturbances and hyponatremia. Antibody-LGI 1 autoimmune encephalitis (anti-LGI1 AE) has increasingly been recognized as a primary autoimmune disorder with favorable prognosis and response to treatment.

CASE PRESENTATION

Herein, we reported a male patient presenting as rapidly progressive dementia and hyponatremia. He had antibodies targeting LGI1 both in the cerebrospinal fluid and serum, which demonstrated the diagnosis of typical anti-LGI1 AE. The scores of Mini-Mental State Examination and Montreal Cognitive Assessment were 19/30 and 15/30, respectively. Cranial magnetic resonance images indicated hyperintensities in bilateral hippocampus. The findings of brain arterial spin labeling and Fluorine-18-fluorodeoxyglucose positron emission tomography showed no abnormal perfusion/metabolism. After the combined treatment of intravenous immunoglobulin and glucocorticoid, the patient's clinical symptoms improved obviously.

CONCLUSIONS

This case raises the awareness that a rapid progressive dementia with predominant memory deficits could be induced by immunoreactions against LGI1. The better recognition will be great importance for the early diagnosis, essential treatment, even a better prognosis.

Bortezomib-induced hyponatremia: tolvaptan therapy permits continuation of lenalidomide, bortezomib and dexamethasone therapy in relapsed myeloma

The development of hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion (SIADH) is well recognised in multiple myeloma (MM). SIADH, due to either MM or Bortezomib can be hazardous as severe hyponatremia may develop if large volumes of hypotonic intravenous fluid are used as an adjunct to chemotherapy. We report a case of Bortezomib-induced SIADH, in whom the use of tolvaptan, a vasopressin receptor-2 antagonist, permitted the continuation of triple combination anti-MM therapy with lenalidomide, Bortezomib and dexamethasone (RVD) in a female with aggressive disease, without the development of hyponatremia. Our patient had a rapid relapse, in which the use of Bortezomib as part of an RVD regimen was life-saving. The use of tolvaptan allowed continuation of therapy that is usually halted in other similarly reported cases. This case highlights the possible use of vaptans, which allows an aquaresis to occur by blocking the antidiuretic effects of vasopressin, as a treatment for Bortezomib-induced hyponatremia.

Practical document on the management of hyponatremia in critically ill patients

Hyponatremia is the most prevalent electrolyte disorder in Intensive Care Units. It is associated with an increase in morbidity, mortality and hospital stay. The majority of the published studies are observational, retrospective and do not include critical patients; hence it is difficult to draw definitive conclusions. Moreover, the lack of clinical evidence has led to important dissimilarities in the recommendations coming from different scientific societies. Finally, etiopathogenic mechanisms leading to hyponatremia in the critical care patient are complex and often combined, and an intensive analysis is clearly needed. A study was therefore made to review all clinical aspects about hyponatremia management in the critical care setting. The aim was to develop a Spanish nationwide algorithm to standardize hyponatremia diagnosis and treatment in the critical care patient.

Difficult-to-treat Syndrome of Inappropriate Antidiuretic Hormone Secretion in a Patient with Secondary Central Nervous System Lymphoma

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is defined as hyponatremia with inappropriately concentrated urine in a euvolemic patient. SIADH is associated with a wide spectrum of clinical conditions. In the hospital, hyponatremia carries significant mortality with a prolonged duration of inpatient stay. It is imperative that the underlying cause is appropriately investigated and such patients are closely monitored. This article presents a case of difficult-to-treat hyponatremia secondary to SIADH in a patient with a rare isolated central nervous system (CNS) relapse from a non-Hodgkin's lymphoma (NHL). A relapse, particularly affecting the CNS, carries a poor prognosis. The patient was started on dexamethasone and offered treatment with methotrexate but declined. The hyponatremia failed to respond to fluid restriction and demeclocycline. The hyponatremia responded to a single dose of tolvaptan. Clinicians should have a low index of suspicion for a relapse of lymphoma as a cause of difficult to treat hyponatremia in any patient who has previously had remission from lymphoma treatment.

SIADH with Severe Hyponatremia in an Elderly Man with Herpes Zoster Infection: A Causal or Casual Association?

Syndrome of inappropriate antidiuretic hormone (SIADH) secretion is the most common cause of hypotonic hyponatremia in hospitalized patients. An elderly man with severe symptomatic hyponatremia (109 mEq/L) was diagnosed with SIADH that was likely secondary to large cutaneous herpes zoster (HZ) infection. Hypertonic saline and tolvaptan improved the patient's sodium levels and clinical condition. A one month after discharge, tolvaptan was withdrawn, due to inadequate prescription criteria, after which hyponatremia relapsed several times and was properly treated; eventually fever and sopor occurred and the patient died. SIADH secondary to HZ may induce life-threatening and long-lasting hyponatremia, which requires a prompt diagnosis and treatment.

Chronic Hyponatremia Due to the Syndrome of Inappropriate Antidiuresis (SIAD) in an Adult Woman with Corpus Callosum Agenesis (CCA)

BACKGROUND Corpus callosum agenesis (CCA) is one of the most common congenital brain abnormalities, and is associated with neurodevelopmental and neuropsychiatric disorders. In CCA, defects in osmoregulation have been reported. This report presents a rare case of chronic hyponatremia associated with the syndrome of inappropriate antidiuresis (SIAD) in a woman with CCA. CASE REPORT A 41-year-old woman presented to the renal unit with symptomatic hyponatremia. In her past medical history, she had a four-year history of systemic arterial hypertension and Sjögren's syndrome, and a three-year history of systemic lupus erythematosus (SLE), which was treated with cyclophosphamide. She had CCA but with irregular neurological follow-up. During the previous eight years, her plasma sodium levels ranged from between 118-134 mEq/L. On this hospital admission, she had plasma hypo-osmolality, measured in milli-osmoles per kilogram of H2O (mOsm/kg H2O), of 251 mOsm/Kg H2O, and a urinary hyper-osmolality of 545 mOsm/Kg H2O, and increased level of plasma antidiuretic hormone (ADH) (1.8 pg/ml). Bone densitometry was consistent with osteoporosis. The patient remained asymptomatic during her hospital stay. Chronic hyponatremia associated with the SIAD was diagnosed. Water restriction and increased protein intake resulted in a partial improvement in the serum sodium level (128-134 mEq/L). The patient was discharged from the hospital with outpatient follow-up. CONCLUSIONS A rare case of chronic hyponatremia due to the SIAD associated with CCA is reported that demonstrates the importance of correct diagnosis, management, and clinical follow-up of the SIAD, including bone densitometry.

Reset Osmostat: A Challenging Case of Hyponatremia

Hyponatremia is the most common electrolyte abnormality seen in hospitalised patients with up to 15-20% of patients having a sodium level of less than 135 mmol/L (Reddy and Mooradian, 2009). Cases of hyponatremia were first described in the 1950s (George et al., 1955). As the differential diagnosis for hyponatremia is broad, a systematic and logical approach is needed to identify the cause. We describe a case of a 30-year-old gentleman who was found to have chronic hyponatremia. After a thorough workup, he was diagnosed to have reset osmostat. Reset osmostat is an uncommon and under recognised cause of hyponatremia which does not require any treatment. This diagnosis needs to be considered when the hyponatremia workup suggests SIADH, but the hyponatremia is not amenable to fluid restriction, salt or urea supplementation, and diuretic treatment.

[CME: Paraneoplastic Endocrine Syndromes]

CME: Paraneoplastic Endocrine Syndromes Abstract. Paraneoplastic endocrine syndromes are caused by ectopic hormone production by malignant tumor cells. Knowledge of paraneoplastic endocrine syndromes may allow a timely diagnosis of the underlying cancer at a treatable stage and, on the other hand, appropriate treatment of the endocrine manifestations reduces morbidity and mortality of the affected patients. The most common endocrine syndromes are paraneoplastic hypercalcaemia, caused by the secretion of PTHrP, and hyponatremia, caused by the inadequate secretion of ADH. Although there may be clinical symptoms like fatigue, nausea/vomiting and renal insufficiency for hypercalcaemia and gait disturbances and mental alterations for hyponatremia, the diagnosis must be confirmed by laboratory testing and prompt the search for associated tumors.

Treatment of Hyponatremia in Patients with Acute Neurological Injury

BACKGROUND

Little data exist regarding the practice of sodium management in acute neurologically injured patients. This study describes the practice variations, thresholds for treatment, and effectiveness of treatment in this population.

METHODS

This retrospective, multicenter, observational study identified 400 ICU patients, from 17 centers, admitted for ≥48 h with subarachnoid hemorrhage (SAH), traumatic brain injury (TBI), intraparenchymal hemorrhage, or intracranial tumors between January 1, 2011 and July 31, 2012. Data collection included demographics, APACHE II, Glascow Coma Score (GCS), serum sodium (Na+), fluid rate and tonicity, use of sodium-altering therapies, intensive care unit (ICU) and hospital length of stay, and modified Rankin score upon discharge. Data were collected for the first 21 days of ICU admission or ICU discharge, whichever came first. Sodium trigger for treatment defined as the Na+ value prior to treatment with response defined as an increase of ≥4 mEq/L at 24 h.

RESULTS

Sodium-altering therapy was initiated in 34 % (137/400) of patients with 23 % (32/137) having Na⁺ >135 mEq/L at time of treatment initiation. The most common indications for treatment were declining serum Na⁺ (68/116, 59 %) and cerebral edema with mental status changes (21/116, 18 %). Median Na⁺ treatment trigger was 133 mEq/L (IQR 129-139) with no difference between diagnoses. Incidence and treatment of hyponatremia was more common in SAH and TBI [SAH (49/106, 46 %), TBI (39/97, 40 %), ICH (27/102, 26 %), tumor (22/95, 23 %); p = 0.001]. The most common initial treatment was hypertonic saline (85/137, 62 %), followed by oral sodium chloride tablets (42/137, 31 %) and fluid restriction (15/137, 11 %). Among treated patients, 60 % had a response at 24 h. Treated patients had lower admission GCS (12 vs. 14, p = 0.02) and higher APACHE II scores (12 vs. 10, p = 0.001). There was no statistically significant difference in outcome when comparing treated and untreated patients.

CONCLUSION

Sodium-altering therapy is commonly employed among neurologically injured patients. Hypertonic saline infusions were used first line in more than half of treated patients with the majority having a positive response at 24 h. Further studies are needed to evaluate the impact of various treatments on patient outcomes.

Endocrinopathy-induced euvolemic hyponatremia

Euvolemic hyponatremia results from either the syndrome of inappropriate antidiuretic hormone secretion (SIADH), hypothyroidism, or adrenal insufficiency. Furthermore, the criteria for diagnosis of SIADH entail the exclusion of hypothyroidism and hypoadrenalism. We aim to assess the yield of euvolemic hyponatremia workup focusing on underlying endocrinopathies in a real-world setting. A single-center retrospective study includes all patients diagnosed with euvolemic hyponatremia in a tertiary hospital between 1.1.2007 and 1.1.2013. Demographic, clinical, and laboratory data were collected from medical charts. Euvolemic hyponatremia was detected in 564 patients. Thyroid function was tested in 69% (391/564) and adrenal function was assessed in 29% (164/564) of cases. Endocrinopathy-induced euvolemic hyponatremia was diagnosed in nine (1.6%) patients: three patients were diagnosed with hypothyroidism-induced hyponatremia, three with adrenal insufficiency as an underlying cause, and three with central hypothyroidism and central hypoadrenalism. All nine had medical history and symptoms suggestive of endocrine deficiencies other than the hyponatremia, which resolved within 1-3 days after administration of hormone replacement therapy. Yield of performed workup for hypothyroidism and hypoadrenalism in euvolemic hyponatremia was low. However, in this real-world study, only a limited number of patients underwent a full ascertainment of hypoadrenalism and hypothyroidism, which was diagnosed only in patients with additional findings supportive of these endocrinopathies; a higher rate of undiagnosed endocrinopathies cannot be ruled out. As both hypoadrenalism and hypothyroidism are easily treatable, potentially life-threatening conditions, there are insufficient data to change current recommendation for their universal evaluation in patients with euvolemic hyponatremia.

Clinical characteristics and short-term prognosis of LGI1 antibody encephalitis: a retrospective case study

Background

Recently, most reports of Leucine-rich glioma-inactivated 1 (LGI1) antibody encephalitis are from Europe and the US, while the short term outcome and clinical characteristics of Chinese patients are rarely reported,we study the clinical manifestations, laboratory results and brain magnetic resonance images (MRI) of eight patients who were recently diagnosed with LGI1 antibody encephalitis in our hospital to improve the awareness and knowledge of this disease.

Methods

Eight patients (five males and three females; mean age, 63.4) with LGI1 antibody encephalitis who were diagnosed and treated in the Department of Neurology of Shengjing Hospital of China Medical University from September 2016 to June 2017 were recruited for the current study. Their general information, clinical manifestations, treatment regimens, and short-term prognoses were retrospectively analyzed, as were the results from MRI and laboratory findings.

Results

Overall, patient symptoms included cognitive impairment, which manifested primarily as memory deficits (8/8), seizures (including faciobrachial dystonic seizure, (FBDS)) (8/8), psychiatric and behavioral disorders (7/8), sleep disorders (4/8), and autonomic abnormalities (3/8). Five patients also had abnormal findings on brain MRI, mainly involving the hippocampus, basal ganglia and insula. Hyponatremia occurred in six cases. All patients tested positive for LGI1 antibodies in their serum/cerebrospinal fluid (CSF)and patients were negative for tumors. Symptoms rapidly improved after treatment with immunoglobulin and/or steroid therapy. The patients were followed up for 4–13 months after discharge, and two patients relapsed.

Conclusion

Primary symptoms of LGI1 antibody encephalitis include memory impairments, seizures, FBDS, and mental and behavioral abnormalities. Increased titers of LGI1 antibodies are also present in the serum/CSF of patients. Patients often have hyponatremia, and MRIs show abnormalities in various brain regions. Finally, immunotherapy shows good efficacy and positive benefits, although patients may relapse in the short-term.

Acute symptomatic hyponatremia following elective rhinoplasty: A case report

We present the first reported case of symptomatic hyponatremia after elective rhinoplasty. A 42-year old female underwent cosmetic rhinoplasty without complication and was discharged home after an uneventful recovery from general anesthesia. Just prior to midnight on the day of surgery, she reported nausea, which was treated with supportive care. Four hours later, she developed emesis, altered mental status, and seizure-like activity prompting medical transport to the emergency department. Upon arrival, she was hypotensive (BP 78/54), tachycardic (HR 112 bpm), hyponatremic (116 mmol/L), hypoosmotic (239 mOsm/kg), and had decreased consciousness (GCS = 10). She was admitted to the intensive care unit and had a central line placed for hypertonic saline infusion. Urinalysis was suggestive of SIADH (UrNa 111 mmol/L, UrOsm 546 mOsm/kg) and Nephrology was consulted. Her serum sodium was corrected over three days and her mental status improved. Surgeons should maintain a low threshold for further evaluation in patients who deviate from the expected postoperative recovery pathway. This report demonstrates that normal postoperative symptoms may mask underlying physiological abnormalities that can progress to acute life-threatening illness and underscores the importance of direct patient observation in the immediate postoperative period.

Practical issues for the management of hyponatremia in oncology

Hyponatremia is common in cancer patients and has a negative impact on outcomes and survival. Both the diagnosis and treatment of hyponatremia are challenging. Easy-to-use, practical guidelines are needed. The aim of this article is to discuss practical issues related to the diagnostic workup and management of hyponatremia, with particular attention to complex patients, such as those affected by neoplastic diseases. Admittedly, these patients may present several comorbidities, which may cause sodium alterations. In addition, multidrug therapy may precipitate serum sodium fall. An algorithm for the diagnosis and treatment of hyponatremia was also developed, based on the discussion of the results of a questionnaire completed by the authors and of the published recommendations/guidelines on hyponatremia. The goal was to produce an algorithm that was as simple as possible but still comprehensive, without compromising information completeness. Many explanatory notes were added with the aim of guiding clinicians throughout the management of complex patients with hyponatremia, such as those with cancer. The resulting algorithm and supporting literature are presented.

Interventions for chronic non-hypovolaemic hypotonic hyponatraemia

BACKGROUND

Chronic (present > 48 hours) non-hypovolaemic hyponatraemia occurs frequently, can be caused by various conditions, and is associated with shorter survival and longer hospital stays. Many treatments, such as fluid restriction or vasopressin receptor antagonists can be used to improve the hyponatraemia, but whether that translates into improved patient-important outcomes is less certain.

OBJECTIVES

This review aimed to 1) look at the benefits and harms of interventions for chronic non-hypovolaemic hypotonic hyponatraemia when compared with placebo, no treatment or head-to-head; and 2) determine if benefits and harms vary in absolute or relative terms dependent on the specific compound within a drug class, on the dosage used, or the underlying disorder causing the hyponatraemia.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 1 December 2017 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov. We also screened the reference lists of potentially relevant studies, contacted authors, and screened the websites of regulatory agencies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs that compared the effects of any intervention with placebo, no treatment, standard care, or any other intervention in patients with chronic non-hypovolaemic hypotonic hyponatraemia. We also included subgroups with hyponatraemia from studies with broader inclusion criteria (e.g. people with chronic heart failure or people with cirrhosis with or without hyponatraemia), provided we could obtain outcomes for participants with hyponatraemia from the report or the study authors.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed risk of bias. We expressed treatment effects as mean difference (MD) for continuous outcomes (health-related quality of life, length of hospital stay, change from baseline in serum sodium concentration, cognitive function), and risk ratio (RR) for dichotomous outcomes (death, response and rapid increase in serum sodium concentration, hypernatraemia, polyuria, hypotension, acute kidney injury, liver function abnormalities) together with 95% confidence intervals (CI).

MAIN RESULTS

We identified 35 studies, enrolling 3429 participants. Twenty-eight studies (3189 participants) compared a vasopressin receptor antagonist versus placebo, usual care, no treatment, or fluid restriction. In adults with chronic, non-hypovolaemic hypotonic hyponatraemia, vasopressin receptor antagonists have uncertain effects on death at six months (15 studies, 2330 participants: RR 1.11, 95% CI 0.92 to 1.33) due to risk of selective reporting and serious imprecision; and on health-related quality of life because results are at serious risk of performance, selective reporting and attrition bias, and suffer from indirectness related to the validity of the Short Form Health Survey (SF-12) in the setting of hyponatraemia. Vasopressin receptor antagonists may reduce hospital stay (low certainty evidence due to risk of performance bias and imprecision) (3 studies, 610 participants: MD -1.63 days, 95% CI -2.96 to -0.30), and may make little or no difference to cognitive function (low certainty evidence due to indirectness and imprecision). Vasopressin receptor antagonists probably increase the intermediate outcome of serum sodium concentration (21 studies, 2641 participants: MD 4.17 mmol/L, 95% CI 3.18 to 5.16), corresponding to two and a half as many people having a 5 to 6 mmol/L increase in sodium concentration compared with placebo at 4 to 180 days (moderate certainty evidence due to risk of attrition bias) (18 studies, 2014 participants: RR 2.49, 95% CI 1.95 to 3.18). But they probably also increase the risk of rapid serum sodium correction - most commonly defined as > 12 mmol/L/d (moderate certainty evidence due to indirectness) (14 studies, 2058 participants: RR 1.67, 95% CI 1.16 to 2.40) and commonly cause side-effects such as thirst (13 studies, 1666 participants: OR 2.77, 95% CI 1.80 to 4.27) and polyuria (6 studies, 1272 participants): RR 4.69, 95% CI 1.59 to 13.85) (high certainty evidence). The potential for liver toxicity remains uncertain due to large imprecision. Effects were generally consistent across the different agents, suggesting class effect.Data for other interventions such as fluid restriction, urea, mannitol, loop diuretics, corticosteroids, demeclocycline, lithium and phenytoin were largely absent.

AUTHORS' CONCLUSIONS

In people with chronic hyponatraemia, vasopressin receptor antagonists modestly raise serum sodium concentration at the cost of a 3% increased risk of it being rapid. To date there is very low certainty evidence for patient-important outcomes; the effects on mortality and health-related quality of life are unclear and do not rule out appreciable benefit or harm; there does not appear to be an important effect on cognitive function, but hospital stay may be slightly shorter, although available data are limited. Treatment decisions must weigh the value of an increase in serum sodium concentration against its short-term risks and unknown effects on patient-important outcomes. Evidence for other treatments is largely absent.Further studies assessing standard treatments such as fluid restriction or urea against placebo and one-another would inform practice and are warranted. Given the limited available evidence for patient-important outcomes, any study should include these outcomes in a standardised manner.

Hyponatremia in children with pneumonia rarely means SIADH

Background

Hyponatremia (HN) < 135 mmol/L is a frequent finding in children with community-acquired pneumonia (CAP). We aimed to determine the proportion of syndrome of inappropriate antidiuretic hormone secretion (SIADH) among patients with CAP and HN. Moreover, we wished to investigate the relationship between HN and inflammatory markers, bacterial etiology and prognosis in hospitalized children with CAP.

Methods

We carried out a prospective, observational, multicentre, prospective cohort study. Eligible participants were children from 1 month to 17 years old hospitalized due to CAP from 2012 to 2015.

Results

A total of 150 children were analyzed. Forty-five (30%) patients had serum sodium levels of less than 135 mmol/L. Patients with HN had significantly higher concentrations of inflammatory biomarkers. They also had significantly lower osmolality and urine sodium. They also had longer hospitalizations and more days of fever. Only 16 out of the 45 (35%) patients with HN had confirmed calculated plasma osmolality (<275 mOsm/kg). Only 5 out of 37 (13%) patients with available measurements of plasma osmolality and urine sodium fulfilled the criteria for SIADH. Among the 16 patients with HN and hypo-osmolality, 15 had a fractional sodium excretion (EFNa) levels of less than 1%. We found a significant inverse linear correlation between serum sodium and C-reactive protein, as well as serum sodium and procalcitonin. We found a significant direct correlation between serum sodium and urine sodium.

Conclusion

HN is a common finding in hospitalized children with CAP. True SIADH is a rare event. HN has a good correlation with inflammatory biomarkers.

Factors associated with residual urine volume preservation in patients undergoing hemodialysis for end-stage kidney disease in Kinshasa

BACKGROUND

Decreased residual urine volume (RUV) is associated with higher mortality in hemodialysis (HD). However, few studies have examined RUV in patients on HD in Sub-Saharan Africa. The aim of this study was to identify predictors of RUV among incident hemodialysis patients in Kinshasa.

METHODS

This historical cohort study enrolled 250 patients with ESRD undergoing hemodialysis between January 2007 and July 2013 in two hemodialysis centers in Kinshasa. RUV were collected over 24 h at the initiation of HD and 6 and 12 months later during the interdialytic period. We compared the baseline characteristics of the patients according to their initial RUV (≤ 500 ml/day vs >  500 ml/day) using Student's t, Mann-Whitney U and Chi2 tests. Linear mixed-effects models were used to search for predictors of decreased RUV by adding potentially predictive baseline covariates of the evolution of RUV to the effect of time: age, sex, diabetes mellitus, hypertension, diastolic blood pressure, diuretics, angiotensin conversion enzyme inhibitors (ACEI), angiotensin receptor blockers, hypovolemia, chronic tubulointerstitial nephropathy, left ventricular hypertrophy and initial hemodialysis characteristic. A value of p < 0.05 was considered the threshold of statistical significance.

RESULTS

The majority of hemodialysis patients were male (68.8%, sex ratio 2.2), with a mean age of 52.5 ± 12.3 years. The population's RUV decreased with time, but with a slight deceleration. The mean RUV values were 680 ± 537 ml/day, 558 ± 442 ml/day and 499 ± 475 ml/day, respectively, at the initiation of HD and at 6 and 12 months later. The use of ACEI at the initiation of HD (beta coefficient 219.5, p < 0.001) and the presence of chronic tubulointerstitial nephropathy (beta coefficient 291.8, p = 0.007) were significantly associated with RUV preservation over time. In contrast, the presence of left ventricular hypertrophy at the initiation of HD was significantly associated with decreased RUV over time (beta coefficient - 133.9, p = 0.029).

CONCLUSIONS

Among incident hemodialysis patients, the use of ACEI, the presence of chronic tubulointerstitial nephropathy and reduced left ventricular hypertrophy are associated with greater RUV preservation in the first year of dialysis.

Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) Associated with Mediastinal Schwannoma

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the most common cause of euvolemic hypo-osmotic hyponatremia. There are several etiologies of SIADH including neuroendocrine tumor, pulmonary disease, infection, trauma, and medications. Here, we report a case of SIADH associated with a schwannoma involving the mediastinum in a 75-year-old woman who presented with nausea, vomiting, and general weakness. Laboratory testing showed hypo-osmolar hyponatremia, with a serum sodium level of 102mmol/L, serum osmolality of 221mOsm/kg, urine osmolality of 382mOsm/kg, urine sodium of 55 mmol/L, and plasma antidiuretic hormone (ADH) of 4.40 pg/mL. Chest computed tomography identified a 1.5-cm-sized solid enhancing nodule in the right lower paratracheal area. A biopsy specimen was obtained by video-assisted thoracoscopic surgery, which was diagnosed on pathology as a schwannoma. The hyponatremia was completely resolved after schwannoma resection and plasma ADH level decreased from 4.40 pg/mL to 0.86 pg/mL. This case highlights the importance of suspecting and identifying the underlying cause of SIADH when faced with refractory or recurrent hyponatremia, and that on possibility is mediastinal schwannoma

[Endocrine paraneoplastic syndromes]

Endocrine paraneoplastic syndromes result from the production of bioactive substances from neoplastic cells, of endocrine or neuroendocrine origin. Typically these are located in the lungs, the gastrointestinal tract, pancreas, thyroid gland, adrenal medulla, skin, prostate or breast. In endocrine paraneoplastic syndromes the secretion of peptides, amines or other bioactive substances is always ectopic and not related to the anatomical source. The clinical presentation, however, is indistinguishable from a suspected eutopic endocrine tumor posing a diagnostic challenge. The most common endocrine paraneoplastic syndromes are based on the secretion of antidiuretic hormone (ADH) resulting in hyponatremia, secretion of adrenocorticotropic hormone (ACTH) or rarely corticotropin-releasing hormone (CRH) resulting in Cushing syndrome as well as secretion of growth hormone-releasing hormone resulting in acromegaly. Paraneoplastic endocrine syndromes mainly occur in highly malignant tumors; however, the development of these tumors does not necessarily correlate with tumor stage, malignant potential or prognosis. As endocrine paraneoplastic syndromes are a rare complication, there are hardly any evidence-based therapeutic recommendations. Treatment of the underlying tumor is the first choice and in a palliative setting symptomatic therapy is possible.

The optimal treatment approaches for stage I small cell lung cancer

Although small cell lung cancer (SCLC) represents less than one-sixth of all lung cancer cases, it is an aggressive disease with a high metastatic potential to various sites including the brain. Most landmark trials assessing individual therapy benefits for SCLC dichotomized patients as having either limited or extensive disease. Over the last decade, however, there has been a clear shift towards categorizing and analyzing survival patterns using a more thorough staging system that accounts for tumor size and the degree of nodal or metastatic disease burden. For the 5% of patients who present with clinical stage I (cT1-2aN0M0) SCLC, extrapolating treatment recommendations from a rather heterogeneous population that constitutes limited disease SCLC remains controversial and has led to numerous investigations of alternative therapies such as stereotactic body radiation therapy (SBRT) for the management of this highly select group of patients. Given the changing landscape of multimodal therapy, this review will summarize relevant data pertaining to and outline optimal treatment algorithms for stage I SCLC, with a particular focus on SBRT as a primary mode of local therapy.

SIADH in Systemic JIA Resolving After Treatment With an IL-6 Inhibitor

Interleukin-6 (IL-6) is implicated in the pathogenesis of both systemic juvenile idiopathic arthritis (SJIA) and syndrome of inappropriate secretion of antidiuretic hormone (SIADH), but the 2 have not been previously described as occurring together. We report a case of a 6-year-old girl with symptoms of arthralgia, daily fevers, evanescent rash, lymphadenopathy, and laboratory evaluation showing elevated inflammatory markers, consistent with SJIA. At presentation, the patient had hyponatremia with a sodium level of 128 mEq/L. She had low serum osmolality with elevated urine osmolality, consistent with SIADH. Hyponatremia improved temporarily during times of fluid restriction as expected in SIADH, but did not resolve until SJIA was treated successfully with tocilizumab, an IL-6 receptor antibody that inhibits IL-6 activity. The positive response to treatment with tocilizumab supports the role of IL-6 in the pathogenesis of both SJIA and SIADH. Patients with SJIA should be monitored for SIADH to avoid complications of untreated hyponatremia.

Hyponatremia: An Unusual Presentation in a Neonate With Chromosome 1q21.1 Deletion Syndrome

Chromosome 1q21.1 deletion syndrome is associated with a wide variety of clinical features including mild to moderate mental retardation, microcephaly, cardiac abnormalities, and cataracts. We report an unusual case of a premature neonate with persistent hyponatremia, markedly elevated plasma arginine vasopressin level (32.7 pg/mL), and clinical findings consistent with the syndrome of inappropriate antidiuretic hormone secretion (SIADH). The patient, who also had microcephaly and dextrocardia, was subsequently diagnosed with chromosome 1q21.1 deletion syndrome. Further evaluation revealed hypothalamic abnormalities, features not previously described with this syndrome. To our knowledge, this is the first report of SIADH associated with congenital hypothalamic anomalies in a neonate with chromosome 1q21.1 deletion syndrome. We also report our experience using tolvaptan, a vasopressin receptor antagonist, in this patient to effectively maintain eunatremia.

Amiodarone-Induced Hyponatremia Masked by Tolvaptan in a Patient with an Implantable Left Ventricular Assist Device

A 43-year-old man was referred to our hospital in June 2014 because of severe heart failure. He was diagnosed with familial dilated cardiomyopathy and was administered oral tolvaptan and amiodarone for atrial and ventricular tachycardia. Since up-titration of carvedilol had failed and he was dependent on dobutamine, a left ventricular assist device (LVAD) was implanted. Tolvaptan and furosemide were both discontinued after LVAD implantation and he was discharged from the hospital. Thirteen months later, he was hospitalized for lethargy and hyponatremia of 108 mEq/L, with an antidiuretic hormone level of 2.5 pg/mL, which suggested syndrome of inappropriate antidiuretic hormone secretion (SIADH). We discontinued amiodarone and administered fludrocortisones. However, hyponatremia persisted for a few more days, eventually resulting in delirium and damage to the LVAD driveline. He received an urgent pump exchange and hyponatremia was gradually improved. We considered the possibility that amiodarone-induced SIADH was masked by tolvaptan therapy before LVAD implantation.