Urine osmolarity predicts the body weight-reduction response to tolvaptan in chronic kidney disease patients: a retrospective, observational study

Identifying the main predictors of urine output in autosomal-dominant polycystic kidney disease (ADPKD) patients taking tolvaptan

BACKGROUND

Few works have analyzed factors associated with urine output in ADPKD patients taking tolvaptan (TVP).

METHODS

We selected 24-h urine samples from ADPKD patients treated with TVP. Urine osmolality/creatinine ratio was used as estimator of urinary osmolar load.

RESULTS

We included 127 urine samples from 61 patients. After TVP, urine output doubled with a parallel reduction in urine solute concentration. However, when expressed as urine solute/creatinine ratios, no significant changes were observed. Daily osmolar load and osmolality/creatinine ratio did not change significantly. Before TVP, urine output was positively correlated with body weight and urine osmolality/creatinine ratio and negatively with eGFR, urine morning osmolality, and 24-h urine-calculated osmolality. After TVP, urine output was positively correlated with body weight, eGFR and negatively with age. There was a poor correlation with urine-calculated osmolality. We constructed a predictor model using mixed-effects modeling and we found that urine output was related to lower age, higher body weight, higher eGFR, and greater doses of TVP. When body weight was removed, urine output was also related to male sex and a higher daily osmolar excretion. Equation of prediction was: Urine output (mL/day) = 2771-52.9 × Age (years) + 58.4 × Weight (kg) + 18.7 × eGFR (mL/min) + 870 (if TVP = 90/30 mg) + 517 (if TVP = 60/30 mg).

CONCLUSION

Patients taking TVP will undergo an increase about twice in urine production from baseline. Greater doses of TVP cause a progressive increase in urine production. GFR, age, and body weight are the main predictors of future urine output in patients taking TVP.

Impact of urine cyclic AMP relative to plasma arginine vasopressin on response to tolvaptan in patients with chronic kidney disease and heart failure

BACKGROUND

The clinical utility of tolvaptan in chronic kidney disease (CKD) patients with heart failure remains uncertain. The level of urine cyclic adenosine monophosphate (AMP) relative to plasma arginine vasopressin (AVP) indicates the residual function of the collecting ducts in response to AVP stimulation and might be a key to predicting response of tolvaptan.

METHODS

CKD patients who were hospitalized to treat their congestive heart failure refractory to conventional loop diuretics were considered to receive tolvaptan and included in this prospective study. The impact of urine cyclic AMP/plasma AVP ratio for prediction of response to tolvaptan, which was defined as any increase in urine volume at day 7 from day 0, was investigated.

RESULTS

A total of 30 patients (median 75 years old, 24 men, and median estimated glomerular filtration rate 14.4 mL/min/1.73 m²) were included. As compared to baseline, urine volume increased at day 7 in 17 responders, whereas urine volume decreased at day 7 in 13 non-responders. Baseline urine cyclic AMP/plasma AVP ratio distributed between 0.25 and 4.01 with median 1.90. The urine cyclic AMP/plasma AVP ratio was a significant predictor of response to tolvaptan, which was adjusted for 6 potential confounders with a cutoff of 1.24.

CONCLUSIONS

Baseline urine cyclic AMP/plasma AVP ratio is an independent predictor of response to tolvaptan in advanced CKD patients with heart failure.

CLINICAL TRIAL REGISTRATION

UMIN000022422.

Tolvaptan Reduces Extracellular Fluid per Amount of Body Fluid Reduction Less Markedly than Conventional Diuretics

Objective Tolvaptan, a vasopressin V2 receptor antagonist, is a water diuretic, removing electrolyte-free water from the kidneys and affecting the water balance between the intracellular and extracellular fluid. We previously reported that tolvaptan efficiently reduced the intracellular fluid volume, suggesting its utility for treating cellular edema. Furthermore, tolvaptan is known for its low incidence of worsening the renal function, with conventional diuretics use associated with worsening of the renal function Methods In this retrospective observational study, five chronic kidney disease (CKD) patients with fluid retention were assessed by the bioelectrical impedance (BIA) method twice (before and after tolvaptan therapy). Tolvaptan was used with conventional diuretics. The post/pre ratio of extracellular water (ECW)/total body water (TBW) in the tolvaptan group was compared with that in 18 CKD patients undergoing body fluid reduction with conventional diuretics alone (conventional diuretics groups), taking the reduced amount of body fluid into consideration. Results Removing body fluid, either by tolvaptan or by conventional diuretics alone, decreased the ECW/TBW ratio. Of note, the reduction in extracellular fluid was milder in the tolvaptan group than in the conventional diuretics group. Conclusion Tolvaptan reduces the extracellular fluid per amount of body fluid reduction less markedly than conventional diuretics.

Effect of Tolvaptan in Patients with Chronic Kidney Disease Stage G5, and Impact of Concomitant Use of Thiazide Diuretics: A Retrospective Cohort Study

BACKGROUND

The diuretic effect of tolvaptan, a vasopressin V2 receptor antagonist, in patients with severe renal dysfunction remains poorly characterized. Thiazide diuretics reduce urinary volume (UV) in patients with nephrogenic diabetes insipidus, which lacks V2 receptor function.

OBJECTIVE

This retrospective study investigated the acute urinary effects of tolvaptan in patients with stage G5 chronic kidney disease and congestive heart failure (CHF), and the impact of thiazide diuretics on the urinary effects of tolvaptan.

METHODS

UVs 24 h before and after tolvaptan administration and 30-day dialysis initiation rate were compared between patients with and without thiazide diuretic administration.

RESULTS

Thiazide diuretics were used in 26 of the 106 recruited patients (age 73.4 ± 13.0 years; estimated glomerular filtration rate 8.07 ± 3.13 mL/min/1.73 m²). The pre- and post-tolvaptan 24-h UVs were significantly higher in patients not administered thiazide diuretics (1043.4 ± 645.6 vs. 1422.2 ± 774.0 mL/day; p < 0.001) than in those administered thiazide diuretics (1177.3 ± 686.5 vs. 1173.1 ± 629.1 mL/day; p = 0.93). In a multivariate regression model, thiazide diuretic use was significantly associated with decreased 24-h UV (β coefficient - 486.7, 95% confidence interval [CI] - 674.5 to - 298.8); increased urine osmolality (β coefficient 37.7, 95% CI 17.1-58.4); increased body weight (β coefficient 0.62, 95% CI 0.31-0.92); and increased 30-day dialysis initiation rate (odds ratio 3.40, 95% CI 1.18-9.82) after tolvaptan administration.

CONCLUSIONS

Tolvaptan exhibited significant diuretic effects in patients with CHF, including those with severe renal dysfunction, which were diminished with concomitant thiazide diuretic use.

The effects of tolvaptan dose on cardiac mortality in patients with acute decompensated heart failure after hospital discharge

Tolvaptan (TLV) is a newly developed oral vasopressin-2 receptor antagonist that is mostly used for patients with acute decompensated heart failure (ADHF) refractory to conventional diuretic therapy. The aim of this study was to investigate the effects of outpatient TLV dose on cardiac mortality in patients discharged after hospitalization for ADHF. One hundred and five patients with ADHF who had been treated with TLV for the first time during hospitalization were retrospectively divided into three groups based on outpatient TLV use and dose. The non-TLV group comprised patients who were not treated with TLV after discharge (n = 36). Patients who continued TLV after discharge were further classified into two groups: low-dose (LD)-TLV (3.75 mg/day, n = 27) and high-dose (HD)-TLV (7.5 or 15 mg/day, n = 42). The primary endpoint was cardiac mortality. Secondary endpoint included the composite of all-cause mortality or re-hospitalization due to worsening of ADHF. There were no significant differences in demographic variables other than body mass index (p = 0.0026), echocardiographic data, laboratory data other than serum chloride before TLV administration (p = 0.041), serum sodium (p = 0.040) and potassium (p = 0.027) at discharge, and concomitant medications among the three groups. The Kaplan-Meier curve showed that the survival rate was lower in HD-TLV than in non-TLV, whereas LD-TLV showed the highest survival rate among the three groups (p = 0.0001). Multivariable Cox regression analysis of the clinical characteristics used for predicting cardiac mortality revealed that LD-TLV (hazard ratio [HR] 0.16, 95% confidence interval [CI] 0.01-0.93, p = 0.040) and HD-TLV (HR 2.43, 95% CI 1.06-6.26, p = 0.035) were significant predictors after adjustment for predictive covariates. In conclusion, the judgement of the continuation of LD-TLV according to patient hemodynamics and severity of congestion may not cause worsened prognosis.

Tolvaptan for Heart Failure in Chronic Kidney Disease Patients: A Systematic Review and Meta-Analysis

BACKGROUND

Heart failure (HF) is frequently associated with renal impairment. Tolvaptan is reported to be effective in treating congestion in HF without significant electrolyte loss compared to conventional diuretics. However, the safety and efficacy of its use in patients with chronic kidney disease (CKD) is uncertain. This systematic review and meta-analysis evaluated the efficacy and safety outcomes of tolvaptan for HF management in patients with CKD, with a focus at a physiologic basis related to safety.

METHODS

We searched for observational studies and randomised clinical trials (RCTs) that assessed the effects of tolvaptan against placebo or standard care in adult patients with HF and CKD. Our protocol was registered with PROSPERO (number CRD42017052775).

RESULTS

Seventeen studies were included in the qualitative review and six in the meta-analysis involving 1597 patients. Tolvaptan was associated with an increase in sodium concentration. No significant differences in change of eGFR and serum creatinine were found between tolvaptan and control groups. Urine flow rate appears to increase significantly with tolvaptan compared to baseline (p<0.0001). The meta-analysis demonstrated no heterogeneity between studies but the possibility of publication bias due to incomplete reporting in excluded studies and lack of RCTs.

CONCLUSIONS

The safety profile of tolvaptan appears acceptable for patients with HF and CKD. There is evidence for an improvement in serum sodium and reduction in body water without deterioration in renal function. Further research is needed to elucidate the long-term benefits of tolvaptan as an adjunct or alternative to diuretics in such patients.

Effects of Tolvaptan Addition to Furosemide in Normo- and Hyponatremia Patients with Heart Failure and Chronic Kidney Disease Stages G3b-5: A Subanalysis of the K-STAR Study

BACKGROUND

Tolvaptan increases free water clearance (aquaresis) and thereby improves hyponatremia. Although hyponatremia on admission is common in patients with congestive heart failure (CHF), little is known regarding the response to tolvaptan in those who also have chronic kidney disease (CKD) with or without hyponatremia. The aim of this subanalysis was to investigate the differences in treatment response between normo- and hyponatremia patients with CHF and CKD stages G3b-5.

METHODS

The Kanagawa Aquaresis Investigators Trial of Tolvaptan on HF Patients with Renal Impairment (K-STAR) was a multicenter, open-label, randomized, controlled prospective clinical trial that included 81 Japanese patients with CHF and residual signs of congestion despite oral furosemide treatment (≥40 mg/day). All patients were randomly assigned to 7-day treatment with either ≤15 mg/day of new add-on tolvaptan or ≤40 mg/day of increased furosemide. A subanalysis was conducted for 73 patients, who were classified into 2 groups according to their assigned treatment, then further stratified into 2 subgroups according to their serum sodium concentration [Na+]. The differences between the urine and serum parameters from day 1 to 3 were compared between the groups and between the subgroups in each group.

RESULTS

The change (Δ) in urine volume (ΔUV) and Δurine osmolality were greater in the tolvaptan group than in the furosemide group; however, ΔUV and Δurine osmolality did not show significant differences between the normonatremia subgroup and the hyponatremia subgroup in each group. In addition, Δserum [Na+] was greater in the tolvaptan group, although the change was not clinically significant. In contrast, Δserum [Na+] did not show significant differences between the normo- and hyponatremia subgroups in each group.

CONCLUSION

Tolvaptan added to furosemide resulted in a greater diuretic effect than increased furosemide, even in normonatremia patients with CHF complicated by CKD stages G3b-5 in the very early treatment phase.

Effects of tolvaptan in patients with chronic kidney disease and chronic heart failure

BACKGROUND

Tolvaptan, a vasopressin V₂ receptor blocker, has a diuretic effect for patients with heart failure. However, there were a few data concerning the effects of tolvaptan in patients with chronic kidney disease (CKD).

METHODS

We retrospectively analyzed 21 patients with chronic heart failure and CKD. Tolvaptan was co-administered with other diuretics in-use, every day. We compared clinical parameters before and after the treatments with tolvaptan. Furthermore, we examined the correlations between baseline data and the change of body weight.

RESULTS

Tolvaptan decreased the body weight and increased the urine volume (p = 0.001). The urine osmolality significantly decreased throughout the study period. Urinary Na/Cr ratio and FENa changed significantly after 4 h, and more remarkable after 8 h (p = 0.003, both). Serum creatinine increased slightly after 1 week of treatment (p = 0.012). The alteration of body weight within the study period correlated negatively with the baseline urine osmolality (r = -0.479, p = 0.038), the baseline urine volume (r = -0.48, p = 0.028), and the baseline inferior vena cava diameter (IVCD) (r = -0.622, p = 0.017). Hyponatremia was improved to the normal value, and the augmentations of the sodium concentration were negatively associated with the basal sodium levels (p = 0.01, r = -0.546).

CONCLUSIONS

Tolvaptan is effective in increasing diuresis and improved hyponatremia, even in patients with CKD. The baseline urine osmolality, urine volume, and IVCD may be useful predictors for diuretic effects of tolvaptan.

Diuretic usage for protection against end-organ damage in liver cirrhosis and heart failure

Volume overload is common in liver cirrhosis, heart failure, and chronic kidney disease, being an independent risk factor for mortality. Loop diuretics have been widely used for treating volume overload in these patients. However, there is a tendency to increase the dose of loop diuretics partly because of diuresis resistance. Neurohormonal factors are also enhanced in these patients, which play a role in volume overload and organ ischemia. Loop diuretics cannot improve neurohormonal factors and could result in end-organ damage. The water diuretic tolvaptan has been approved for use for volume overload in heart failure and liver cirrhosis. Despite causing similar increases in urine volume, its characteristics differ from those of loop diuretics. Renal blood flow is maintained with tolvaptan but decreased with furosemide in heart failure patients. Neurohormonal factors and blood pressure are not markedly altered by tolvaptan administration. It is expected that these mechanisms of tolvaptan can protect against worsening renal function by volume overload diseases compared with loop diuretics. It has also been reported that some patients do not respond well to tolvaptan. Loop diuretics and tolvaptan share the same mechanism with regard to decreasing renal interstitial osmolality, which plays a fundamental role in water diuresis. Thus, a high dose of loop diuretics could result in resistance to tolvaptan, so tolvaptan should be administered before increasing the loop diuretic dose. Therefore, volume control without enhancing end-organ damage can be achieved by adding tolvaptan to a tolerable dose of Na-sparing diuretics.

Different Effects of Tolvaptan in Patients with Idiopathic Membranous Nephropathy with Nephrotic Syndrome

This case report discusses the clinical indication for immunosuppressants in patients with idiopathic membranous nephropathy (IMN). Because this disease occasionally shows spontaneous remission, it is necessary to determine the predictive values for a therapeutic effect in order to provide appropriate treatment. Two distinct cases described herein illustrate the different effects of tolvaptan in responders and non-responders, according to the pre-treatment levels of AQP-2 immunostaining in the samples from renal biopsy and urinary levels of AQP-2 and osmolality, suggesting that these values may be useful predictors of response to tolvaptan in patients with nephrotic IMN.

Clinical Factors Predicting the Effect of Tolvaptan for Refractory Ascites in Patients with Decompensated Liver Cirrhosis

OBJECTIVE

Refractory ascites reduces the quality of life of liver cirrhosis patients. Albumin preparation and diuretics, such as furosemide, have been used to treat refractory ascites, but the effect was poor in many patients. In this study, we analyzed patients treated with tolvaptan (TLV) at our hospital and investigated predictors of the effect.

METHODS

The subjects were 70 patients for whom TLV was introduced to treat refractory ascites who could be analyzed between November 2013 and March 2015 at our hospital. Patient background before initiation of oral TLV treatment, the dose of diuretics, and each item of biochemical tests of blood and urine were investigated, and factors correlated with the treatment effect were analyzed. An increase of ≥1,000 ml in the daily urine volume from the day before oral treatment or a decrease of ≥1 kg in the body weight within 7 days as an early effect was observed in 33 patients and not observed in 37 patients. TLV treatment was continued for 60 days or longer in 12 of the 37 patients in whom no early effect was observed, and the presence or absence of a delayed effect and predictors of the effect were investigated. A decrease in ascites on abdominal CT with improvement of subjective symptoms at 60 days was defined as a delayed effect.

RESULTS

When early predictors of the effect were investigated by univariate analysis, serum blood urea nitrogen (BUN) and serum creatinine (Cr) were significantly higher in the non-responder group (BUN: p = 0.03, Cr: p = 0.04), but no factor independently associated with the treatment effect was extracted on multivariate analysis. The delayed effect was noted in 4 (33.3%) of the 12 patients, but no predictor of the effect before treatment was identified. However, reactions, such as an increase in serum Na and reduction of urinary osmotic pressure, were observed early after TLV administration in some patients in whom the delayed effect was observed.

CONCLUSIONS

The diuretic effect of TLV may decrease in renal hypofunction patients. Since the delayed effect was noted in a specific ratio of patients, continuation of TLV administration is an option even though the early treatment effect is poor unless ascites aggravates or adverse effects develop.

Urine Aquaporin-2: A Promising Marker of Response to the Arginine Vasopressin Type-2 Antagonist, Tolvaptan in Patients with Congestive Heart Failure

Aquaporin-2, a member of the aquaporin family, is an arginine vasopressin-regulated water channel expressed in the renal collecting duct, and a promising marker of the concentrating and diluting ability of the kidney. The arginine vasopressin type-2 antagonist, tolvaptan, is a new-generation diuretic; it is especially indicated in patients with decompensated heart failure refractory to conventional diuretics. However, the ideal responders to tolvaptan have not yet been identified, and non-responders experience worse clinical courses despite treatment with tolvaptan. Urine aquaporin-2 has recently been demonstrated as a promising predictor of response to tolvaptan. We here validated aquaporin-2-guided tolvaptan therapy in patients with decompensated heart failure. Long-term efficacy of tolvaptan treatment in the responders defined by aquaporin-2 needs to be validated in the future prospective study.