The Effect of Furosemide on the Level of Neutrophil Gelatinase-associated Lipocalin in Critically Hospitalized Patients with Acute Kidney Injury

Diuretics for preventing and treating acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is a well-known complication of critical illnesses, significantly affecting morbidity and the risk of death. Diuretics are widely used to ameliorate excess fluid accumulation and oliguria associated with AKI. Their popularity stems from their ability to reduce the energy demands of renal tubular cells by inhibiting transporters and flushing out intratubular casts. Numerous studies have assessed the effects of diuretics in the context of AKI prevention and treatment. However, a comprehensive systematic review addressing this topic has yet to be conducted.

OBJECTIVES

This review aimed to explore the benefits and harms of diuretics for both the prevention and treatment of AKI.

SEARCH METHODS

The Cochrane Kidney and Transplant Register of Studies was searched up to May 2024 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 Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) and quasi-RCTs in which diuretics were used to prevent or treat AKI.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data using standardised data extraction forms. Dichotomous outcomes were expressed as risk ratios (RR) with 95% confidence intervals (CI). Where continuous scales of measurement were used to assess the effects of treatment, the standardised mean difference (SMD) was used. The primary review outcomes for AKI prevention studies were the incidence of AKI and any use of kidney replacement therapy (KRT). For treatment studies, the primary outcome was any use of KRT. The certainty of evidence was assessed per outcome using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 64 studies (83 reports, 9871 participants): 53 prevention studies (8078 participants) and 11 treatment studies (1793 participants). Studies were conducted in the following World Health Organization regions: the Americas (15), Eastern Mediterranean (9), Europe (25), South-East Asia (2), and the Western Pacific (13). Thirty-six studies were single-centre studies, 19 were multicentre, and the setting was unclear in nine studies. Diuretics were compared to placebo, no treatment or conventional therapy, saline solutions (isotonic or hypotonic), 5% dextrose, 5% glucose, Hartmann's solution, and Ringer's acetate. Overall, the risk of bias was low in one study, high in 19 studies, and of some concern in 41 studies. Three studies could not be assessed because they did not report any outcomes of interest. For AKI prevention, compared to control, diuretics may reduce the risk of AKI (38 studies, 5540 participants: RR 0.75, 95%, CI 0.61 to 0.92; I2 = 77%; low-certainty evidence) and probably reduce any use of KRT (32 studies, 4658 participants: RR 0.63, 95% CI 0.43 to 0.91; I2 = 0%, moderate-certainty evidence) and death (33 studies, 6447 participants: RR 0.73, 95% CI 0.59 to 0.92; I2 = 0%; moderate-certainty evidence). The use of diuretics may result in little or no difference in the need for permanent dialysis (2 studies, 956 participants: RR 0.52, 95% CI 0.08 to 3.47; I2 = 21%; low-certainty evidence), hypotension (7 studies, 775 participants: RR 1.27, 95% CI 0.87 to 1.86; I2 = 0%; low-certainty evidence) and hypokalaemia (6 studies, 1383 participants: RR 1.20, 95% CI 0.88 to 1.73; I2 = 43%; low-certainty evidence), and had uncertain effects on arrhythmias (13 studies, 3375 participants: RR 0.77, 95% CI 0.57 to 1.04; I2 = 53%; very-low certainty evidence). Diuretics may make little or no difference to changes in SCr within 30 days (8 studies, 646 participants: SMD 0.41, 95% CI -0.01, to 0.83; I2 = 82%; low-certainty evidence) but it was uncertain whether diuretics increased urinary output (8 studies, 1155 participants: SMD 1.87, 95% CI -0.20 to 3.95; I2 = 99%; very low-certainty evidence). For AKI treatment, diuretics may make little or no difference to any use of KRT (8 studies, 1275 participants: RR 0.93, 95% CI 0.83 to 1.04; I2 = 2%; low-certainty evidence) or death (14 studies, 2052 participants: RR 1.08, 95% CI 0.96 to 1.22; I2 = 0%; low-certainty evidence). Diuretics may increase hypotension (2 studies, 720 participants: RR 1.99, 95% CI 1.16 to 3.41; I2 = 90%; low-certainty evidence) and probably increase arrhythmias (6 studies, 1011 participants: RR 1.62, 95% CI 1.12 to 2.33; I2 = 0%; moderate-certainty evidence). Diuretics may result in little or no difference in hypokalaemia (3 studies, 478 participants: RR 1.52, 95% CI 0.70 to 3.31; I2 = 0%; low-certainty evidence). It was uncertain whether diuretics increased urinary output (3 studies, 329 participants: SMD 4.40, 95% CI -0.94 to 9.74; I2 = 99%; very low-certainty evidence). The need for permanent dialysis and changes in serum creatinine were not reported.

AUTHORS' CONCLUSIONS

When used for the prevention of AKI, diuretics may reduce the risk of AKI. However, our confidence in the effect estimate is limited. Diuretics probably reduce the incidence of KRT use, and we are moderately confident in the effect estimate. When used for the treatment of AKI, diuretics may make little or no difference to any use of KRT, and our confidence in the effect estimate is limited. More RCTs are needed to explore the role of diuretics for treating established AKI.

Evaluation of urinary neutrophil gelatinase-associated lipocalin to detect renal tubular damage in dogs with stable myxomatous mitral valve disease

BACKGROUND

Dogs with myxomatous mitral valve disease (MMVD) can experience progressive renal tubular damage and dysfunction. The prevalence of renal tubular damage is not known in dogs with stable MMVD.

OBJECTIVE

To evaluate renal tubular damage in dogs with stable MMVD by evaluation of urinary neutrophil gelatinase-associated lipocalin (NGAL).

ANIMALS

Ninety-eight MMVD dogs grouped according to the American College of Veterinary Internal Medicine (ACVIM) staging (group B1, n = 23; group B2, n = 27; group C + D, n = 48) and 46 healthy dogs.

METHODS

Multicenter prospective observational study. Serum and urine chemistry including NGAL reported as uNGAL concentration (uNGAL) and normalized with urinary creatinine (uNGALC) were compared between MMVD dogs and healthy controls, and among different MMVD ACVIM stages.

RESULTS

The MMVD dogs had significantly higher uNGAL and uNGALC (1204 pg/mL; range, 30-39 732 and 1816 pg/mg; range, 22-127 693, respectively) compared to healthy dogs (584 pg/mL; range, 56-4072 and 231 pg/mg; range, 15-2407, respectively; P = .002 and P < .0001, respectively). Both uNGAL and uNGALC increased with the increasing ACVIM stage (P = .001 and P < .001, respectively).

CONCLUSIONS AND CLINICAL IMPORTANCE

Renal tubular damage is present in dogs with stable MMVD, as measured by increased uNGAL. This tubular damage is subclinical, occurs in all stages of MMVD even in the absence of azotemia, and increases with the severity of MMVD. Reno-protective approaches to manage MMVD dogs should be explored to slow the progression of renal tubular damage in these patients.

Loop diuretics in adult intensive care patients with fluid overload: a systematic review of randomised clinical trials with meta-analysis and trial sequential analysis

BACKGROUND

Fluid overload is a risk factor for organ dysfunction and death in intensive care unit (ICU) patients, but no guidelines exist for its management. We systematically reviewed benefits and harms of a single loop diuretic, the predominant treatment used for fluid overload in these patients.

METHODS

We conducted a systematic review with meta-analysis and Trial Sequential Analysis (TSA) of a single loop diuretic vs. other interventions reported in randomised clinical trials, adhering to our published protocol, the Cochrane Handbook, and PRISMA statement. We assessed the risks of bias with the ROB2-tool and certainty of evidence with GRADE. This study was registered in the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42020184799).

RESULTS

We included 10 trials (804 participants), all at overall high risk of bias. For loop diuretics vs. placebo/no intervention, we found no difference in all-cause mortality (relative risk (RR) 0.72, 95% confidence interval (CI) 0.49-1.06; 4 trials; 359 participants; I2 = 0%; TSA-adjusted CI 0.15-3.48; very low certainty of evidence). Fewer serious adverse events were registered in the group treated with loop diuretics (RR 0.81, 95% CI 0.66-0.99; 6 trials; 476 participants; I2 = 0%; very low certainty of evidence), though contested by TSA (TSA-adjusted CI 0.55-1.20).

CONCLUSIONS

The evidence is very uncertain about the effect of loop diuretics on mortality and serious adverse events in adult ICU patients with fluid overload. Loop diuretics may reduce the occurrence of these outcomes, but large randomised placebo-controlled trials at low risk of bias are needed.

Trial of Furosemide to Prevent Acute Kidney Injury in Critically Ill Children: A Double-Blind, Randomized, Controlled Trial

OBJECTIVE

To study whether furosemide infusion in early-onset acute kidney injury (AKI) in critically ill children would be associated with a reduced proportion of patients progressing to the higher stage (Injury or Failure) as compared to placebo.

METHOD

A double-blind, placebo-controlled, randomized pilot trial was conducted. The authors enrolled children aged 1-mo (corrected) to 12-y, who were diagnosed with AKI ("risk" stage) using pediatric-Risk, Injury, Failure, Loss, End stage kidney disease (p-RIFLE) criteria, and achieved immediate resuscitation goals within 24 h of admission. Participants received either furosemide (0.05 to 0.4 mg/kg/h) or placebo (5%-dextrose) infusion. The primary outcome was the proportion of patients progressing to a higher stage (injury or failure). Secondary outcomes were (i) need for renal replacement therapy, (ii) the effect on neutrophil gelatinase-associated lipocalin (urine and blood), (iii) fluid balance, (iv) adverse effects, (v) time to achieve renal recovery, (vi) duration of hospital stay and mechanical ventilation, and (vii) all-cause 28-d mortality.

RESULTS

The trial was stopped for futility, and data were analyzed on an intention-to-treat basis (furosemide-group: n = 38; placebo-group: n = 37). No significant difference was noted in the progression of AKI to a higher stage between furosemide and placebo groups (10.5% vs. 21.6%; relative risk = 0.49, 95% CI 0.16 to 1.48) (p = 0.22). There were no differences in the secondary outcomes between the study groups. All-cause 28-d mortality was similar between the groups (10.5% vs. 10.8%). No trial-related severe adverse events occurred.

CONCLUSIONS

Furosemide infusion in early-onset AKI did not reduce the progression to a higher stage of AKI. A future trial with large sample size is warranted.

Effect of 3% saline and furosemide on biomarkers of kidney injury and renal tubular function and GFR in healthy subjects - a randomized controlled trial

Background

Chloride is speculated to have nephrotoxic properties. In healthy subjects we tested the hypothesis that acute chloride loading with 3% saline would induce kidney injury, which could be prevented with the loop-diuretic furosemide.

Methods

The study was designed as a randomized, placebo-controlled, crossover study. Subjects were given 3% saline accompanied by either placebo or furosemide. Before, during and after infusion of 3% saline we measured glomerular filtration rate (GFR), fractional excretion of sodium (FE_Na), urinary chloride excretion (u-Cl), urinary excretions of aquaporin-2 (u-AQP2) and epithelial sodium channels (u-ENaC_γ), neutrophil gelatinase-associated lipocalin (u-NGAL) and kidney injury molecule-1 (u-KIM-1) as marker of kidney injury and vasoactive hormones: renin (PRC), angiotensin II (p-AngII), aldosterone (p-Aldo) and arginine vasopressin (p-AVP). Four days prior to each of the two examinations subjects were given a standardized fluid and diet intake.

Results

After 3% saline infusion u-NGAL and KIM-1 excretion increased slightly (u-NGAL: 17 ± 24 during placebo vs. -7 ± 23 ng/min during furosemide, p = 0.039, u-KIM-1: 0.21 ± 0.23 vs − 0.06 ± 0.14 ng/ml, p <  0.001). The increase in u-NGAL was absent when furosemide was given simultaneously, and the responses in u-NGAL were not significantly different from placebo control. Furosemide changed responses in u-KIM-1 where a delayed increase was observed. GFR was increased by 3% saline but decreased when furosemide accompanied the infusion. U-Na, FE_Na, u-Cl, and u-osmolality increased in response to saline, and the increase was markedly pronounced when furosemide was added. FE_K decreased slightly during 3% saline infusion, but simultaneously furosemide increased FE_K. U-AQP2 increased after 3% saline and placebo, and the response was further increased by furosemide. U-ENaC_γ decreased to the same extent after 3% saline infusion in the two groups. 3% saline significantly reduced PRC, p-AngII and p-Aldo, and responses were attenuated by furosemide. p-AVP was increased by 3% saline, with a larger increase during furosemide.

Conclusion

This study shows minor increases in markers of kidney injury after 3% saline infusion Furosemide abolished the increase in NGAL and postponed the increase in u-KIM-1. The clinical importance of these findings needs further investigation.

Trial registration

(EU Clinical trials register number: 2015–002585-23, registered on 5th November 2015)