Role of tolvaptan in the management of hyponatremia in patients with lung and other cancers: current data and future perspectives

Identification of different lung adenocarcinoma subtypes in combination with antidiuretic hormone-related genes and creation of an associated index to predict prognosis and guide immunotherapy

BACKGROUND

Lung adenocarcinoma (LUAD) is one of the most aggressive and rapidly lethal tumor types. Previous studies have demonstrated the involvement of antidiuretic hormone (ADH)-related genes in cancer. However, the role of ADH-related genes in LUAD remains unclear. Therefore, investigating the characteristics of these genes in LUAD is essential.

METHODS

Differentially expressed genes (DEGs) associated with ADH in LUAD were identified using the STRING database. Consensus clustering was performed, and a protein-protein interaction network was constructed for the DEGs between subtypes. Genes extracted from the PPI network underwent univariate, LASSO, and multivariate Cox regression analyses to develop a predictive model for LUAD. A nomogram integrating clinical data and risk scores was created, and its prognostic power for overall survival (OS) in LUAD patients was evaluated. Additionally, LUAD patients were analyzed for targeted therapies, immune landscape, functional enrichment, and mutation profiles. Finally, qRT-PCR was used to examine the expression of signature genes in LUAD cells.

RESULTS

Based on ADH-related DEGs, LUAD patients were stratified into two clusters (Cluster 1 and Cluster 2) with distinct survival outcomes. A predictive model incorporating nine feature genes was subsequently constructed using DEGs from these two subtypes. The receiver operating characteristic curve demonstrated the model's prognostic accuracy in predicting OS in LUAD patients. Compared to the high-risk group, patients in the low-risk group exhibited higher immune infiltration levels and immunophenoscore, along with lower tumor immune dysfunction and exclusion scores. Enrichment analysis revealed that immune response pathways and ligand-receptor interactions were the primary functional categories distinguishing the high- and low-risk groups. The low-risk group showed a significantly lower gene mutation burden. Drug sensitivity analysis identified several potential targeted therapies, including Dabrafenib, ARQ-680, Vemurafenib, BGB-283, MLN-2480, and GDC-0994, which might act on hub genes. qRT-PCR validation confirmed that DNAH12 was significantly downregulated in tumor tissues, while DKK1, DLX2, IGFBP1, NTSR1, RPE65, and VGF were markedly upregulated.

CONCLUSION

This study provided potential prognostic biomarkers for LUAD and might facilitate the development of effective immunotherapy strategies for LUAD patients.

Mechanisms of hyponatremia and diabetes insipidus after acute spinal cord injury: a critical review

The incidence of hyponatremia after spinal cord injury was reported to be between 25 and 80%. Hyponatremia can lead to a variety of clinical symptoms, from mild to severe and even life-threatening. Hyponatremia is often associated with diabetes insipidus, which refers to insufficient arginine vasopressin (AVP) secretion or defective renal response to AVP, with clinical manifestations of syndromes such as hypoosmolality, polydipsia, and polydipsia. Recent mechanistic studies on hyponatremia and diabetes insipidus after acute spinal cord injury have been performed in isolation, without integrating the above two symptoms into different pathological manifestations that occur in the same injury state and without considering the acute spinal cord injury patient's condition as a whole. The therapeutic principles of CSWS and SIADH are in opposition to one another. It is not easy to identify the mechanism of hyponatremia in clinical practice, which makes selecting the treatment difficult. According to the existing theories, treatments for hyponatremia and diabetes insipidus together are contraindicated, whether the mechanism of hyponatremia is thought to be CSWS or SIADH. In this paper, we review the mechanism of these two pathological manifestations and suggest that our current understanding of the mechanisms of hyponatremia and diabetes insipidus after high acute cervical SCI is insufficient, and it is likely that there are other undetected pathogenetic mechanisms.

Clinical characteristics of paraneoplastic syndromes in patients with head and neck cancer

Background

To summarize the clinical manifestations, diagnosis, and prognosis of head and neck cancer (HNC) patients with paraneoplastic syndromes (PNS).

Methods

The clinical data of 1958 patients with HNC admitted to our hospital from January 1996 to December 2020 were retrospectively analyzed. Demographic and cancer-related characteristics were extracted. Kaplan-Meier survival curves were compared by log-rank test. Cox regression was performed to evaluate prognostic factors and hazard ratio.

Results

Totally 40 HNC patients with PNS were included in the final analysis, including 36 men and four women with a mean age of 60.4 years (range 40-82). PNS was dermatologic or cutaneous in 23 (57.50%) patients, endocrine in 10 (25.00%), neurologic in five (12.50%), and osteoarticular or rheumatologic in two (5.00%). Twenty-five (62.50%) patients had Stage III/IV cancer. PNS regressed after antitumor therapy in 28 (70.00%) patients. Recurrence of PNS was observed in nine of 12 (75.00%) patients with cancer recurrence or metastasis. The 5-year overall survival (OS) and disease-free survival (DFS) rates of patients with PNS were 51.52% and 44.44%, respectively. The DFS (p = .001) and OS (p = .003) of patients presented with PNS prior to HNC diagnosis were significantly longer than those of patients with synchronous or metachronous PNS. PNS diagnosed before HNC (adjusted hazard ratio [aHR]: 0.31, 95% confidence interval [CI]: 0.11-0.85, p = .02), Stage IV disease (aHR: 3.27, 95% CI: 1.18-9.05, p = .02), and smoking history (aHR: 3.69, 95% CI: 1.04-13.05, p = .04) were significantly associated with OS and DFS.

Conclusions

Early recognition of PNS could provide clues about underlying tumor condition and result in early diagnosis. Prompt detection of cancer-associated syndromes could lead to a more favorable prognosis for these patients.

Tolvaptan Improves Contrast-Induced Acute Kidney Injury

OBJECTIVE

Contrast-induced acute kidney injury (CI-AKI) is a serious side effect of contrast media use. The purpose of this study was to investigate the role and mechanism of tolvaptan (TOL) in CI-AKI.

METHODS

24 Wistar male rats were randomly divided into 4 groups (n = 6). And a rat model of CI-AKI was established. Then, the blood and urine of rats in each group were collected to detect relevant parameters. HE staining was utilized for the observation of the pathological changes of rat kidney tissues, TUNEL assay for the detection of tubular cell apoptosis, biochemical detection for the confirmation of oxidative stress level in kidney tissues, and western blot for the test of the expression of apoptotic proteins and the Nrf2 signaling pathway-related proteins in kidney tissues.

RESULTS

TOL could significantly reduce the serum level of urea nitrogen, creatinine, and neutrophil gelatinase-associated lipocalin and decrease serum Cys-C and urine KIM-1 in CI-AKI rats. The result above meant that TOL could improve kidney injury and reduce tubular cell apoptosis in CI-AKI rats. In addition, TOL contributed to a reduction of oxidative stress level by downregulating myeloperoxidase level and increasing the activities of superoxide dismutase and glutathione peroxidase in the kidney tissue of CI-AKI rats. After the pretreatment of TOL, the expression of proapoptotic proteins cleaved-caspase 3 and BAX, as well as mitochondrial fusion proteins DRP1 and MFN2 was downregulated, while the expression of Bcl-2 and PINK1 was upregulated in the kidney tissue of CI-AKI rats. Further, TOL could activate the Nrf2 signaling pathway, and the Nrf2 inhibitor ML385 reversed the effect of TOL on CI-AKI.

CONCLUSION

TOL can improve CI-AKI by activating the Nrf2/HO-1 signaling pathway, inhibiting oxidative stress response, and reducing tubular cell apoptosis.

Prevalence and Prognostic Significance of Hyponatremia in Patients With Lung Cancer: Systematic Review and Meta-Analysis

Background: The prevalence of hyponatremia is highly variable among patients with lung cancer. However, its prevalence and prognostic significance in subgroups of patients with lung cancer have not yet been evaluated in a meta-analysis. Methods: We have registered our meta-analysis and review protocol to the PROSPERO International Prospective Register of Systematic Reviews, with the following registration number: CRD42020167013. A systematic search was done in the following sources: MEDLINE, Embase, CENTRAL, Web of Science, ClinicalTrials.gov, a WHO Global Health Library. Results: We identified a total of 8,962 potentially eligible studies, and we included 31 articles in our evaluation. The prevalence of hyponatremia in patients with lung cancer varied between 3 and 94.8% with an average of 25% without any significant differences between the following subgroups: histotype, gender, age, Eastern Cooperative Oncology Group (ECOG) state, and the extent of disease. The overall survival (OS) was significantly lower in hyponatremic compared to normonatremic patients at 10 months [RR.59 (95% CI.47-0.74), p < 0.001] and at 20 months [RR.44 (95% CI.33-0.59), p < 0.001], with worse survival rates in non-small cell lung cancer (NSCLC) [RR.27 (95% CI.12-0.44), p < 0.001] than in small cell lung cancer (SCLC) [RR.42 (95% CI.27-0.57), p < 0.001]. If hyponatremia was corrected, OS at 10 months was significantly higher than in the uncorrected hyponatremia group [RR 1.83 (95% CI 1.37-2.44), p < 0.001], but, at 20 months, no statistically significant difference could be found between these subgroups [RR 2.65 (95% CI.94-7.50), p = 0.067]. Conclusions: Patients with lung cancer diagnosed with hyponatremia, especially patients with NSCLC, seem to have significantly lower survival rates than normonatremic patients. If hyponatremia remains uncorrected, the mortality rates might be even higher.

Aquaporins and diseases pathogenesis: From trivial to undeniable involvements, a disease-based point of view

Aquaporins (AQPs), as transmembrane proteins, were primarily identified as water channels with the ability of regulating the transmission of water, glycerol, urea, and other small-sized molecules. The classic view of AQPs involvement in therapeutic plan restricted them and their regulators into managing only a narrow spectrum of the diseases such as diabetes insipidus and the syndrome of inappropriate ADH secretion. However, further investigations performed, especially in the third millennium, has found that their cooperation in water transmission control can be manipulated to handle other burden-imposing diseases such as cirrhosis, heart failure, Meniere's disease, cancer, bullous pemphigoid, eczema, and Sjögren's syndrome.

A narrative review of progress in diagnosis and treatment of small cell lung cancer patients with hyponatremia

Small cell lung cancer (SCLC) is one of the malignant cancers of lung tumors, and hyponatremia, defined as serum sodium concentration (Na⁺) lower than 135 mmol/L, is the most common complication of solid tumors, with an incidence of up to 18.9% and a negative impact on quality of life in SCLC. As a prognostic index of SCLC, timely monitoring and correcting of hyponatremia is of great clinical significance for prolonging the survival period of patients. In the explore of new drugs for small cell lung cancer, it is necessary to include hyponatremia as an evaluation index in clinical studies. As the occurrence of hyponatremia is sometimes unavoidable owing to SCLC specific neurological characteristics, early monitoring to detect the presence of hyponatremia and timely correction are helpful to improve the prognosis of patients. There are many predisposing factors for hyponatremia, including heterotopia of antidiuretic hormone (ADH), use of platinum-based chemotherapy drugs, and intracranial metastasis, among others. Patients with small cell lung cancer are usually asymptomatic in the early stage, while it is of great significance to find a suitable clinical index to judge whether it is a malignant inducement or not. In the clinical setting, due to different electrolyte levels and therapeutic scheduling for the primary disease, an individualized plan is often made, mainly comprising water restriction, infusion, and medications. This review includes related clinical studies and describes the common symptoms and predisposing factors of hyponatremia in patients with SCLC, and their impact on quality of life and prognosis.

Tolvaptan treatment in hyponatremia due to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH): effects on survival in patients with cancer

PURPOSE

To investigate the clinical outcomes of patients with hyponatremia who received supportive treatment or tolvaptan plus supportive treatment and the effects of treatment and other variables on overall survival METHODS: This study included oncology patients who were hospitalized at two oncology centers between January 1, 2016 and December 31, 2019 for hyponatremia (sodium levels < 135 mEq/L) and who received tolvaptan plus supportive treatment (n = 22) or supportive treatment only (n = 42).

RESULTS

The median age of all the patients was 59 years (range 26-85) and 64.1% of the patients were male. There was no statistically significant difference between patients in the tolvaptan plus supportive treatment (TpST) group and the supportive treatment only (ST) group in terms of gender and age (p > 0.05). In the TpST group, recovery days of the hyponatremia after treatment and the length of hospital stay was shorter and hyponatremia symptoms and hospital complications were less frequent compared to the ST group (p < 0.05). There was no significant difference between the TpST group and the ST group in terms of overall survival (OS). OS was shorter in men who were non-responders to hyponatremia treatment and had recurrent hyponatremia. Multivariable analysis showed that normal sodium levels after treatment decreased the risk of death.

CONCLUSION

In the treatment of hyponatremia in cancer patients, TpST was found to have more positive effects on blood sodium levels, length of hospital stay, hospital complications, and hyponatremia symptoms compared to ST. A decreased risk of death was observed in patients with normal sodium levels after treatment.

Hyponatremia in patients with cancer

PURPOSE OF REVIEW

Hyponatremia is seen commonly in patients with cancer and is associated with increased mortality and morbidity. Understanding the proper diagnosis and therapy of cancer-associated hyponatremia is critical to ensure improved outcomes.

RECENT FINDINGS

The most common cancers associated with hyponatremia are the various forms of lung cancer with incidences approaching 25-45%. The most common causes of hyponatremia in cancer patients are the syndrome of inappropriate antidiuretic hormone secretion [syndrome of inappropriate antidiuretic hormone (ADH)] and volume depletion. Proper diagnosis rests on clinical information supplemented by laboratory studies and is critical to ensure appropriate therapy. In recent years, the development of drugs that specifically antagonize the vasopressin type 2 receptor in the distal tubule have offered targeted and highly effective therapies for syndrome of inappropriate ADH.

SUMMARY

Hyponatremia in cancer patients generally indicates advanced or severe disease but proper therapy that targets the underlying process can improve outcomes.

Inappropriate Antidiuretic Hormone Secretion and Cerebral Salt-Wasting Syndromes in Neurological Patients

The differential diagnosis of syndrome of inappropriate antidiuretic hormone secretion (SIADH) and cerebral salt-wasting syndrome (CSWS) in patients with neurological disorders has been a perplexing clinical controversy. The purpose of this review is to summarize the characteristics and risk factors of patients with different types of neurological disorders complicated by hyponatremia (HN) and review various methods to distinguish SIADH from CSWS. Common neurological disorders with high rates of HN include subarachnoid hemorrhage (SAH), traumatic brain injuries, stroke, cerebral tumors, central nervous system (CNS) infections, and Guillain-Barré syndrome (GBS), which have their own characteristics. Extracellular volume (ECV) status of patients is a key point to differentiate SIADH and CSWS, and a comprehensive assessment of relevant ECV indicators may be useful in differentiating these two syndromes. Besides, instead of monitoring the urinary sodium excretion, more attention should be paid to the total mass balance, including Na⁺, K⁺, Cl^-, and extracellular fluid. Furthermore, the dynamic detection of fractional excretions (FE) of urate before and after correction of HN and a short-term infusion of isotonic saline solution may be useful in identifying the etiology of HN. As for brain natriuretic peptide (BNP) or N-terminal prohormone of BNP (NT-proBNP), more prospective studies and strong evidence are needed to determine whether there is a pertinent and clear difference between SIADH and CSWS.

Syndrome of inappropriate anti-diuretic hormone secretion in cancer patients: results of the first multicenter Italian study

BACKGROUND

Hyponatremia in cancer patients is often caused by the syndrome of inappropriate antidiuretic hormone secretion (SIADH). The aim of this observational multicenter study was to analyze the medical and economic implications of SIADH in this setting.

METHODS

This study included 90 oncological patients from 28 Italian institutions that developed SIADH between January 2010 and September 2015. Data on clinical-pathological characteristics, anticancer therapies, hyponatremia, and related treatments were statistically analyzed.

RESULTS

The majority were lung cancer patients (73%) with metastatic disease at the onset of hyponatremia (83%). A total of 76 patients (84%) were hospitalized because of SIADH and less than half (41%) received tolvaptan for SIADH treatment. The duration of hospitalization was significantly longer in patients who did not receive tolvaptan and in those who do not reach sodium normalization during hospitalization. Patients who experienced a second episode of hyponatremia following tolvaptan dose modification/discontinuation presented a significantly lower serum sodium value at the time of hospitalization and minimum sodium value during hospitalization compared with patients who had not experienced another episode. The severity of hyponatremia, defined as minimum sodium value during hospitalization with a cut-off value of 110 mmol/l, and not obtaining sodium correction during hospitalization significantly correlated with overall survival rate.

CONCLUSIONS

Hyponatremia due to SIADH could result in longer hospitalization and in a decreased overall survival when not adequately treated, and tolvaptan represents an effective treatment with a potential effect of both improving overall survival and decreasing duration of hospitalization.

Small molecules for modulating the localisation of the water channel aquaporin-2-disease relevance and perspectives for targeting local cAMP signalling

The tight spatial and temporal organisation of cyclic adenosine monophosphate (cAMP) signalling plays a key role in arginine-vasopressin (AVP)-mediated water reabsorption in renal collecting duct principal cells and in a plethora of other processes such as in the control of cardiac myocyte contractility. This review critically discusses in vitro- and cell-based screening strategies for the identification of small molecules that interfere with AVP/cAMP signalling in renal principal cells; it features phenotypic screening and approaches for targeting protein-protein interactions of A-kinase anchoring proteins (AKAPs), which organise local cAMP signalling hubs. The discovery of novel chemical entities for the modulation of local cAMP will not only provide tools for elucidating molecular mechanisms underlying cAMP signalling. Novel chemical entities can also serve as starting points for the development of novel drugs for the treatment of human diseases. Examples illustrate how screening for small molecules can pave the way to novel approaches for the treatment of certain forms of diabetes insipidus, a disease caused by defects in AVP-mediated water reabsorption.

Urea in cancer patients with chronic SIAD-induced hyponatremia: Old drug, new evidence

BACKGROUND

Syndrome of inappropriate antidiuresis (SIAD) is the main cause of hyponatremia in cancer patients. International guidelines indicate urea as an interesting option for chronic SIAD. Nevertheless, strong data to support its use are lacking, and its role in oncologic patients has not been described so far.

MATERIAL AND METHODS

We retrospectively analysed 36 cancer patients affected by moderate or profound SIAD-induced chronic hyponatremia, who started oral urea (initial daily dose 15 g or 30 g) without fluid restriction between July 2013 and July 2018. We analysed mean serum sodium (sNa) increase after 24 hours and percentages of patients who reached eunatremia within 14, 30 and 60 days of treatment, stratifying according to the degree of hyponatremia at diagnosis. Clinical evaluation and biochemical assessment were periodically performed.

RESULTS

Mean sNa was 123 [±4] mmol/L at baseline; after 24 hours of treatment, a mean increase of 5 [±3] mmol/L was observed. Eunatremia was reached by 55.6%, 86.1% and 91.7% patients within 14, 30 and 60 days of treatment, respectively. Trends in sNa normalization were similar in patients with moderate and profound hyponatremia at diagnosis. Rapid sNa overcorrection was avoided in all cases. Urea  was interrupted within  the first  2 months  of treatment in 10 patients, in half cases for rapid neoplastic progression and in the remaining patients for the drug taste.

CONCLUSIONS

In our study, urea was effective in correcting chronic hyponatremia among cancer patients with SIAD. Almost all patients reached eunatremia within the first month of therapy, and urea was globally well tolerated.

Endocrine paraneoplastic syndromes in patients with neuroendocrine neoplasms

OBJECTIVE

Our aim was to assess the prevalence of endocrine paraneoplastic syndromes (EPNS) in neuroendocrine neoplasms (NENs) and estimate its impact on patient outcomes.

DESIGN

This is a retrospective analysis of 834 patients with NENs (611 gastrointestinal, 166 thoracic, 57 of unknown and various other primary origin). We included 719 consecutive NEN patients treated at EKPA-Laiko Hospital, Athens, Greece and 115 patients with lung carcinoid (LC) treated at Uppsala University Hospital, Uppsala, Sweden. EPNS diagnosis was based on standard criteria.

METHODS

Twenty-one patients with EPNS were detected: 16 with ectopic Cushing's syndrome (ECS), one with hypercalcaemia due to parathyroid hormone-related protein (PTHrP) secretion, three with hypercalcitonaemia and one patient with dual secretion of calcitonin and beta-human chorionic gonadotropin (β-HCG). All tumours were well-differentiated; 10 patients had Stage IV disease at diagnosis.

RESULTS

The prevalence of EPNS in the Greek cohort was 1.9%, whereas that of ECS among LC patients in both centres was 6.7%. Median overall survival (OS) for patients with EPNS was 160.7 months (95%CI, 86-235.4) and median event-free survival (EFS) was 25.9 months (95%CI, 0-57.2). Patients presenting with EPNS prior to NEN diagnosis had longer EFS compared to patients with synchronous or metachronous EPNS (log-rank P = 0.013). Patients with ECS of extra-thoracic origin demonstrated shorter OS and EFS compared to patients with ECS of lung or thymic origin (log-rank P = 0.001 and P < 0.001, respectively). LC patients with and without ECS were comparable in 5-year and 10-year OS rates (66.7% and 33.3% versus 89.8% and 60.2%, respectively; 95%CI [189.6-300.4 months], log-rank P = 0.94) and in median EFS, 67 versus 183 months, 95%CI [50.5-207.5], log-rank P = 0.12).

CONCLUSION

EPNS are relatively rare in patients with NENs and mainly concern well-differentiated tumours of the foregut. Among patients with EPNS, LC-related ECS may not adversely affect patient outcomes when diagnosed prior to NEN and effectively been treated.

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 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.

Use of tolvaptan vs. furosemide in older patients with heart failure : Meta-analysis of randomized controlled trials

BACKGROUND

It is not known whether older patients with acute heart failure (HF) receiving tolvaptan have decreased mortality rates and a better long-term prognosis than patients who receive furosemide. We conducted a systematic review of randomized controlled trials (RCTs) to address this issue.

METHODS

The Medline, Embase, and Cochrane Library databases were searched for English-language RCTs published before September 2016 comparing tolvaptan with furosemide treatment in older patients (>65 years old) after acute HF. The primary outcomes assessed were 6‑month all-cause mortality and worsening renal function (WRF); the secondary outcomes were electrolyte disorders, hospital readmissions, and adverse events.

RESULTS

Out of 669 citations, six RCTs met the inclusion criteria for this meta-analysis. There was a significant decrease in WRF (relative risk [RR] = 0.67, 95% confidence interval [CI] = 0.52-0.86, p = 0.002) and in the hospitalization period (mean difference [MD] = -1.86, 95% CI = -3.70--0.02, p = 0.05), as well as a significant increase in urine volume within 3 days of tolvaptan administration (MD = 1.59, 95% CI = 1.41-1.76, p < 0.00001). There were significant differences in creatinine levels between subgroups (MD = 0.33, 95% CI = 0.14-0.52, p = 0.0006). However, for the outcome of 6‑month all-cause mortality (RR = 0.56, 95% CI = 0.29-1.06, p = 0.07), there was no significant difference among all subgroups. There were significant differences in serum sodium concentration (MD = 0.68, 95% CI = 0.02-1.34, p = 0.04) but no significant changes in systolic blood pressure (MD = 3.57, 95% CI = -2.33-9.47, p = 0.24) between groups.

CONCLUSION

In older patients, tolvaptan relieves WRF, reduces the hospitalization period, and increases urine volume without significant effects on blood pressure. However, surprisingly, the use of tolvaptan did not influence 6‑month all-cause mortality.

Tolvaptan rescue contrast-induced acute kidney injury: A case report

RATIONALE

Contrast-induced acute kidney injury is one of the most serious adverse effects of contrast media and is related to three distinct but interacting mechanisms: medullary ischemia, formation of reactive oxygen species and direct tubular cell toxicity, especially in the patients with chronic kidney disease. The strategies of treatment, including stabilization of hemodynamic parameters and maintenance of normal fluid and electrolyte balance, were similar to the management of other types of acute kidney injury.

PATIENT CONCERNS

A 58-year-old woman experienced acute oligouria after complex percutaneous coronary intervention for multiple vessel coronary artery disease.

DIAGNOSES

Chest radiography showed pulmonary congestion and hyponatremia was noted after fluid hydration for suspicious contrast-induced nephropathy.

INTERVENTIONS

Oral tolvaptan, at 15mg per day, was used for three days.

OUTCOMES

Urine output increased gradually and symptoms relieved one day later after using tolvaptan. Serum creatinine also improved to baseline level one week later after this event.

LESSONS

Here, we reported an interesting case about contrast-induced acute kidney injury and hypervolemic hyponatremia, where tolvaptan was used to rescue the oliguric phase. Tolvaptan could be considered to use for contrast-induced acute kidney injury and had possibility of prevention from hemodialysis. Larger studies are still needed to investigate the role of tolvaptan in rescuing the oliguric phase in contrast-induced acute kidney injury.

Rapidity of Correction of Hyponatremia Due to Syndrome of Inappropriate Secretion of Antidiuretic Hormone Following Tolvaptan

BACKGROUND

Tolvaptan effectively corrects hyponatremia due to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), but undesired overcorrection can occur. We hypothesized that pretherapy parameters can predict the rapidity of response to tolvaptan in SIADH.

STUDY DESIGN

Multicenter historical cohort study.

SETTING & PARTICIPANTS

Adults with SIADH or congestive heart failure (CHF) treated with tolvaptan for a serum sodium concentration ≤ 130 mEq/L at 5 US hospitals.

PREDICTORS

Demographic and laboratory parameters.

OUTCOMES

Rate of change in serum sodium concentration.

MEASUREMENTS

Spearman correlations, analysis of variance, and multivariable linear mixed-effects models.

RESULTS

28 patients with SIADH and 39 patients with CHF treated with tolvaptan (mean baseline serum sodium, 120.6 and 122.4 mEq/L, respectively) were studied. Correction of serum sodium concentration > 12 mEq/L/d occurred in 25% of patients with SIADH compared to 3% of those with CHF (P<0.001). Among patients with SIADH, the increase in serum sodium over 24 hours was correlated with baseline serum sodium concentration (r=-0.78; P<0.001), serum urea nitrogen concentration (SUN; r=-0.76; P<0.001), and estimated glomerular filtration rate (r=0.58; P=0.01). Baseline serum sodium and SUN concentrations were identified as independent predictors of change in serum sodium concentration in multivariable analyses. When patients were grouped into 4 categories according to baseline serum sodium and SUN median values, those with both low baseline serum sodium (≤121 mEq/L) and low baseline SUN concentrations (≤10mg/dL) exhibited a significantly greater rate of increase in serum sodium concentration (mean 24-hour increase of 15.4 mEq/L) than the other 3 categories (P<0.05). Among patients with CHF, only baseline SUN concentration was identified as an independent predictor of change in serum sodium concentration over time.

LIMITATIONS

Lack of uniformity in serial serum sodium concentration determinations and documentation of water intake.

CONCLUSIONS

Baseline serum sodium and SUN values are predictive of the rapidity of hyponatremia correction following tolvaptan use in SIADH. We advise caution when dosing tolvaptan in patients with both low serum sodium and SUN concentrations.

[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.

Acute kidney injury in cancer patients and impedance cardiography-assisted renal replacement therapy: Experience from the onconephrology unit of a Chinese tertiary hospital

Acute kidney injury (AKI) in cancer patients may disrupt anticarcinogenic treatment and greatly increase associated mortality rates. The present study reported on the management of cancer patients with AKI and, from the nephrologic viewpoint, on the significance of fine volume control during the continuous renal replacement therapy (CRRT). The records of 117 cancer patients with AKI treated over three years were reviewed and their data were compared with those of 120 healthy controls. AKI was defined according to the Kidney Disease: Improving Global Outcomes criteria with serum creatinine levels determined on initial admission and for the diagnosis of AKI. CRRT with concomitant impedance cardiography (ICG) monitoring was performed in 79 patients. On average, AKI manifested as a 1.68±0.38-fold increase in serum creatinine within 10.2±5.7 days. The causes of AKI were diverse, with the major ones being nephrotoxic agents, hypotension and obstructive nephropathy. Renal biopsy confirmed two cases of thrombotic microangiopathy, due to the use of interfon-α and sunitinib malate, respectively, and a third case of cast nephropathy caused by immunoglobulin D multiple myeloma. The patients were generally marantic and had compromised cardiac function compared with the healthy controls. The CRRT prescription was discriminatingly optimized by the ICG parameters effecting discreet fluid balance, as the thoracic fluid content was significantly correlated with the ultrafiltration rate. By considering the causative mechanisms and applying subtle ICG-assisted volume control, the present study may thus help to improve the safety and efficacy of CRRT in cancer patients with AKI. In addition, it provided information to bring advances in onconephrology, a novel nephrological subspecialty field.

Pure small cell recurrent prostate cancer developing syndrome of inappropriate antidiuretic hormone secretion

PURPOSE

Pure small cell neuroendocrine carcinoma of the prostate is a rare entity characterized by a poor prognosis due to early metastatic spread as well as resistance to treatment. Considering its increasing occurrence, clinicians should be aware of its aggressive behavior, the relevance of an early diagnosis, and proper management.

METHODS

A 71-year-old man treated with brachytherapy for localized low-risk prostate cancer developed widespread disease 7 years later with a prostate-specific antigen-negative neuroendocrine small cell phenotype. He was also diagnosed with syndrome of inappropriate antidiuretic hormone secretion (SIADH) soon after starting chemotherapy.

RESULTS

A substantial radiologic and clinical response to chemotherapy was observed and the paraneoplastic SIADH was successfully treated with oral vaptan therapy.

CONCLUSIONS

Secondary small cell prostate carcinoma is an underestimated entity with high sensitivity to chemotherapy, although a standard treatment has not yet been defined. Moreover, oral vaptans demonstrated prompt efficacy and simple management in correcting SIADH-related hyponatremia.

The Outcome of Cirrhotic Patients with Ascites Is Improved by the Normalization of the Serum Sodium Level by Tolvaptan

Objective Hyponatremia is frequently observed in patients with decompensated liver cirrhosis and it is also related to a poor prognosis. The vasopressin V2-receptor antagonist tolvaptan is used to treat cirrhotic patients with ascites and increases the serum sodium (Na) level. In this study, we investigated (i) whether or not correction of the Na level improves the prognosis of cirrhotic patients with ascites and (ii) predictors of normalization of the serum Na level after tolvaptan therapy. Methods This was a single-center retrospective study. A total of 95 Japanese cirrhotic patients (60 men, median age 63 years) were enrolled and received tolvaptan orally after hospitalization for ascites treatment. The serum Na level was monitored during the period of tolvaptan treatment. The laboratory data and survival rates of patients who achieved serum Na levels of <135 and ≥135 mEq/L after 1 week were compared. Results Patients showed serum Na levels of 136 (121-145) mEq/L, and 42.1% had a serum Na level of <135 mEq/L. Among patients with an initial serum Na level <135 mEq/L, 60.0% achieved a normal level after 1 week, and the survival rate was significantly higher in patients with a normalized serum Na level (p<0.01). The pretreatment brain natriuretic peptide (BNP) level was predictive of achieving a serum Na level of ≥135 mEq/L (odds ratio: 0.87, 95% confidence interval: 0.316-0.987, p<0.05). Conclusion Normalization of the Na level after one week was associated with a favorable outcome of tolvaptan therapy, and Na correction improved the prognosis.

Managing hyponatremia in lung cancer: latest evidence and clinical implications

Hyponatremia is the most common electrolyte disorder in lung cancer patients. This condition may be related to many causes including incidental medications, concurrent diseases and side effects of antineoplastic treatments or the disease itself. Although not frequently life-threatening, it is usually associated with prolonged hospitalization, delays in scheduled chemotherapy, worsening of patient performance status and quality of life and may also negatively affect treatment response and survival. Most of the available data focus on thoracic tumors, especially small-cell lung cancer (SCLC), where hyponatremia is frequently related to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Few studies specifically focus on non-small cell lung cancer (NSCLC) patients. Hyponatremia treatment needs to be personalized based on severity and duration of sodium serum reduction, extracellular fluid volume and etiology. However, literature data highlight the importance of early correction of the serum concentration levels. To achieve this the main options are fluid restriction, hypertonic saline, loop diuretics, isotonic saline, tolvaptan and urea. The aim of this review is to analyze the role of hyponatremia in lung cancer patients, evaluating causes, diagnosis, management and clinical implications.

Paraneoplastic endocrine syndromes

The majority of neoplasms are responsible for symptoms caused by mass effects to surrounding tissues and/or through the development of metastases. However, occasionally neoplasms, with or without endocrine differentiation, acquire the ability to secrete a variety of bioactive substances or induce immune cross-reactivity with the normal tissues that can lead to the development of characteristic clinical syndromes. These syndromes are named endocrine paraneoplastic syndromes when the specific secretory components (hormones, peptides or cytokines) are unrelated to the anticipated tissue or organ of origin. Endocrine paraneoplastic syndromes can complicate the patient's clinical course, response to treatment, impact prognosis and even be confused as metastatic spread. These syndromes can precede, occur concomitantly or present at a later stage of tumour development, and along with the secreted substances constitute the biological 'fingerprint' of the tumour. Their detection can facilitate early diagnosis of the underlying neoplasia, monitor response to treatment and/or detect early recurrences following successful initial management. Although when associated with tumours of low malignant potential they usually do not affect long-term outcome, in cases of highly malignant tumours, endocrine paraneoplastic syndromes are usually associated with poorer survival outcomes. Recent medical advances have not only improved our understanding of paraneoplastic syndrome pathogenesis in general but also enhanced their diagnosis and treatment. Yet, given the rarity of endocrine paraneoplastic syndromes, there is a paucity of prospective clinical trials to guide management. The development of well-designed prospective multicentre trials remains a priority in the field in order to fully characterise these syndromes and provide evidence-based diagnostic and therapeutic protocols.