Novel Finding of Urinary Erythropoietin as an Early Biomarker of Cisplatin-Induced Nephrotoxicity.

Cisplatin is a chemotherapeutic drug used to treat a great variety of solid tumors. Its dose is commonly limited by its nephrotoxicity, manifested as acute kidney injury (AKI). Erythropoietin (Epo) is a glycoprotein hormone that regulates the production of red blood cells. This study was performed to evaluate the presence of endogenous Epo in male Wistar rat urine and to analyse changes in urinary Epo levels in response to cisplatin- induced AKI. Dose-dependent studies and time-dependent experiments were performed to evaluate changes in urea nitrogen and creatinine in plasma as well as Epo, neutrophil gelatinase-associated lipocalin (NGAL), alkaline phosphatase (AP) activity, creatinine and total proteins in urine at 2 days post-dosing. Rats received 2, 5 or 10 mg/kg b.w., i.p. of cisplatin. At 5 mg/kg b.w., i.p. cisplatin, significant increases in urinary Epo were detected. Significant increases in urea nitrogen and creatinine in plasma, NGAL, AP, proteins, and Epo were observed in urine from rats that received 10 mg/kg b.w., i.p. of cisplatin. In the time-dependent experiments, rats were injected with a dose of 5 mg/kg b.w., i.p. of cisplatin, and sampling occurred 2, 4, and 14 days post-dosing. In these animals, there were significant increases in urea nitrogen and creatinine in plasma and total proteins, AP activity, Epo, and NGAL in urine on day 4. Urinary Epo was also detected on day 2. Taken together, these findings provide weight of evidence for urinary Epo as a promising early biomarker of cisplatin-induced AKI in male rats.

Synergistic effect of apoptosis and necroptosis inhibitors in cisplatin-induced nephrotoxicity.

Necroptosis is a nonapoptotic cell death pathway. We aim to study the effect of necrostatin-1 (a specific necroptosis inhibitor) in cisplatin-induced injury. We analyzed the effect of the combined use of inhibitors of apoptosis (z-vad) and necroptosis (necrostatin-1) in acute kidney injury by cisplatin in human proximal tubule cells. Our results showed moderate effectiveness in cytoprotection after treatment with z-vad. But the concomitant use of inhibitors (z-vad and necrostatin-1) presented synergistic and additive protection. The present study analyzed the caspase-3 activity and we observed a significant decrease in the group treated with z-vad and cisplatin. However we did not observe changes in the group treated with both inhibitors (z-vad and necrostatin-1) and cisplatin. Thus, demonstrating that necroptosis is a caspase-independent mechanism. We also analyzed the effect of necrostatin-1 in vivo model. C57BL/6 mice were treated with cisplatin and/or inhibitors. The concomitant use of inhibitors (z-vad and necrostatin-1) recovered renal function and decreased levels of urinary Ngal. Additionally, we analyzed the expression of RIP-1, a specific marker for necroptosis. In animals treated with cisplatin and z-VAD levels of RIP-1 were higher. This result reinforces that necroptosis occurs only in conditions where apoptosis was blocked. However, the use of both inhibitors (z-vad and necrostatin-1) provided additional protection. In conclusion, our study has a significant potential to show in vitro and in vivo protection obtained by necrostatin-1. Therefore, our results suggest that necroptosis may be an important mechanism of cell death after kidney injury.

Assessment of fractional excretion of urea for early diagnosis of cardiac surgery associated acute kidney injury.

BACKGROUND: Acute kidney injury (AKI) is a common complication after cardiac surgery (CS). Recently, neutrophil gelatinase-associated lipocalin (NGAL) was shown to predict AKI development earlier than serum creatinine, but it is not widely used in clinical practice. Fractional excretion of urea (FeU) has been referred to as a useful tool to discriminate between prerenal and established AKI. The aim of our study is to evaluate the sensitivity and specificity of FeU, in the early diagnosis of AKI in patients undergoing CS. METHODS: We performed a prospective study on adults undergoing CS. AKI was defined by AKIN criteria. Individuals suffering from CKD, were excluded. Sensitivity and specificity of FeU, fractional excretion of sodium (FeNa) and urine NGAL, measured at 1, 6 and 24 h following CS, were assessed. RESULTS: We included 66 patients (26% female) aging 68 ± 11 years. AKI prevalence was 24% and mortality was 3.28%. Patients with AKI had a significantly lower FeU compared to those without AKI (23.89 ± 0.67% vs. 34.22 ± 0.58%; p < 0.05) 6 h after CS, but not at the 1- and 24-h time points. NGAL was also statistically significant between both groups. FeU showed a 75% sensitivity and 79.5% specificity; the AUC was 0.786. ROC analysis of FeU and NGAL yielded similar values (p = NS). CONCLUSION: FeU is useful as an early biomarker to predict AKI after CS and it is comparable to the new biomarker NGAL.

Sepsis and AKI in Clinical Emergency Room Patients: The Role of Urinary NGAL.

BACKGROUND: Few studies have investigated the predictive properties of urinary (u) NGAL as an AKI marker in septic population. OBJECTIVES: This study evaluated the efficacy of uNGAL as predictor of AKI and death in septic patients admitted to the clinical emergency room (ER). METHODOLOGY: We prospectively studied patients with sepsis admitted to the ER. Urine was analyzed for NGAL within the first 24 hours after admission (classified as NGAL1), between 24 and 48 h (NGAL2), and at moment of AKI diagnosis (NGAL3). RESULTS: Among 168 septic patients admitted to ER, 72% developed AKI. The uNGAL and its relationship with creatinine (Cr) were high in septic patients but statistically higher in those with sepsis and AKI. The uNGAL1 and uNGAL2, as well as uNGAL1/uCr1 and uNGAL2/uCr2, were good predictors for AKI (AUC-ROC 0.73, 0.70, 0.77, and 0.84, resp.). The uNGAL1 and uNGAL1/uCr1 were poor predictors for death (AUC-ROC 0.66 and 0.68, resp.), whereas uNGAL2 and uNGAL2/uCr2 were better predictors (AUC-ROC 0.70 and 0.81, resp.). CONCLUSION: The uNGAL is highly sensitive but nonspecific predictor of AKI and death in septic patients admitted into ER.

Relative and absolute changes in urinary neutrophil gelatinase-associated lipocalin and correlation with small increases in serum creatinine levels after coronary angiography: an observational study.

INTRODUCTION/AIMS: The Acute Kidney Injury Network classification is based on small increases in serum creatinine (sCr) for stage 1. This study investigated whether changes in the urinary concentration of neutrophil gelatinase-associated lipocalin (uNGAL) could predict small increases in sCr in patients undergoing coronary angiography. METHODS: The uNGAL was measured before contrast infusion and 2 and 4 h afterwards. Patients were divided into 2 subgroups: G1 (n = 103), where sCr increased by <0.3 mg/dl, and G2 (n = 22), where sCr increased by ≥0.3 mg/dl 48 h after the angiography. To determine the sensitivity and specificity for the absolute and relative variations of uNGAL, a receiver operating characteristic curve analysis was performed. RESULTS: In G2, the uNGAL concentration increased over baseline values (15.9 vs. 9.2 ng/dl; p < 0.05), and it was also 2-fold higher in G2 versus G1 (15.9 vs. 8.0 ng/dl; p < 0.001). The uNGAL remains an independent predictor of the small increases in sCr, and, for an increase of 50% over baseline levels, it showed 60% sensitivity and 81% specificity. CONCLUSION: Changes in uNGAL concentration 2 h after the infusion of contrast media showed marginal sensitivity to predict small increases in sCr.

Biomarkers of renal function, which and when?

PURPOSE OF THE REVIEW: Acute kidney injury (AKI) and chronic kidney disease (CKD) are conditions that substantially increase morbidity and mortality. Although novel biomarkers are being used in practice, the diagnosis of AKI and CKD is still made with surrogate markers of GFR, such as serum creatinine (SCr), urine output and creatinine based estimating equations. SCr is limited as a marker of kidney dysfunction in both settings and may be inaccurate in several situations, such as in patients with low muscle mass or with fluid overload. New biomarkers have the potential to identify earlier patients with AKI and CKD and in the future potentially intervene to modify outcomes. RECENT FINDINGS: In particular KIM-1 and NGAL are considered excellent biomarkers in urine and plasma for the early prediction of AKI; however cycle arrest biomarkers have emerged as novel markers for risk stratification of AKI. Urine TIMP-2 and IGFBP7 performed better than any other biomarkers reported to date for predicting the development of moderate or severe AKI. Biomarker combinations are required to increase diagnostic accuracy in an acute setting. NGAL, cystatin C, and FGF-23 are promising and accurate biomarkers for CKD detection. Equations combining cystatin C and SCr perform better than the equations using either cystatin C or SCr alone, especially in situations where CKD needs to be confirmed. Combining creatinine, cystatin C and urine albumin to creatinine ratio improves risk stratification for kidney disease progression and mortality. SUMMARY: Recent advances in molecular biology have resulted in promising biomarkers for AKI and CKD diagnoses; however more research is necessary to implement them successfully into clinical practice in order to facilitate early diagnosis, guide interventions and monitor disease progression. The following review describes the most important biomarkers studied in kidney disease and will discuss the use and the value of these biomarkers in different clinical settings.

NGAL urinária em pacientes sem e com lesão renal aguda em unidade de terapia intensiva / Urinary NGAL in patients with and without acute kidney injury in a cardiology intensive care unit

Objetivo: Avaliar a eficácia diagnóstica e prognóstica da lipocalina associada à gelatinase neutrofílica urinária em pacientes de unidade de terapia intensiva. Métodos: Estudo do tipo coorte, prospectivo, longitudinal desenvolvido em uma unidade de terapia intensiva clínica especializada em cardiologia. Os pacientes foram estratificados segundo os grupos sem e com lesão renal aguda, acompanhados a partir das primeiras 24 horas de internação até a alta hospitalar ou óbito. A creatinina sérica, o fluxo urinário e a lipocalina associada à gelatinase neutrofílica urinária foram coletadas em dois períodos: 24 horas e 48 horas de admissão. Resultados: Foram avaliados 83 pacientes clínicos da unidade de terapia intensiva, com predomínio do gênero masculino (57,8%). Os pacientes foram agrupados em sem lesão renal aguda (N=18), com lesão renal aguda (N=28) ou com lesão renal aguda grave (N=37). Entre os pacientes com lesão renal aguda e lesão renal aguda grave, foram prevalentes os portadores de doenças crônicas, em uso de ventilação mecânica e em terapia de substituição renal, além daqueles com maiores taxas de permanência na unidade de terapia intensiva e hospitalar, e maior mortalidade. O grupo com lesão renal aguda não apresentou alteração significativa da creatinina sérica nas primeiras 24 horas na unidade de terapia intensiva, ...

Objective: To assess the diagnostic and prognostic efficacy of urine neutrophil gelatinase-associated lipocalin in patients admitted to an intensive care unit. Methods: Longitudinal, prospective cohort study conducted in a cardiology intensive care unit. The participants were divided into groups with and without acute kidney injury and were followed from admission to the intensive care unit until hospital discharge or death. Serum creatinine, urine output and urine neutrophil gelatinase-associated lipocalin were measured 24 and 48 hours after admission. Results: A total of 83 patients admitted to the intensive care unit for clinical reasons were assessed, most being male (57.8%). The participants were divided into groups without acute kidney injury (N=18), with acute kidney injury (N=28) and with severe acute kidney injury (N=37). Chronic diseases, mechanical ventilation and renal replacement therapy were more common in the groups with acute kidney injury and severe acute kidney injury, and those groups exhibited longer intensive care unit stay and hospital stay and higher mortality. Serum creatinine did not change significantly in the group with acute kidney injury within the first 24 hours of admission to the intensive care unit, although, urine neutrophil gelatinase-associated lipocalin was high in the groups with acute kidney injury and severe acute kidney injury (p<0.001). Increased urine neutrophil gelatinase-associated lipocalin was associated with death. ...

Evaluation of the cisplatin nephrotoxicity using the urinary neutrophil gelatinase-associated lipocalin (NGAL) in patients with head and neck cancer.

INTRODUCTION: Acute kidney injury (AKI) in patients receiving cisplatin is common, therefore the evaluation of renal function in patients on use of nephrotoxic drugs is fundamental. OBJECTIVE: To evaluate the incidence of AKI and the role of lipocalin associated to neutrophil gelatinase (NGAL) in the monitoring of renal function in patients with head and neck cancer (HNC) who received cisplatin. METHODS: We prospectively studied 50 patients with HNC treated with three sessions of cisplatin. Blood and urine were collected 24 hours before cisplatin, 24 hours after infusion, 48 hours after each application and 35 days after the end of treatment (urine NGAL, C-reactive protein, creatinine, glomerular filtration rate, plasma lactate dehydrogenase and magnesium). RESULTS: AKI was observed in 78% of patients. There was increase in creatinine, and decrease in GFR after each cycle of cisplatin, and increased urine NGAL. Positive association was observed between the levels of NGAL, creatinine and C-reactive protein. It was observed an increase in creatinine, NGAL, C-reactive protein and decreased GFR in AKI patients compared to patients without AKI. CONCLUSION: AKI was noted in 78% of patients with HNC treated with cisplatin and showed the correlation of NGAL with creatinine and GFR in demonstrating renal injury. NGAL levels may be elevated compared to baseline levels, even before the use of cisplatin.

Urinary excretion of neutrophil gelatinase-associated lipocalin in diabetic rats.

UNLABELLED: Recent studies suggest that tubular damage precedes glomerular damage in the progression of diabetic nephropathy. Therefore, we evaluated oxidative stress and urinary excretion of tubular proteins as markers of tubular dysfunction. METHODS: Diabetes was induced in rats by streptozotocin administration (50 mg/kg). Oxidative stress was assessed by measuring the activity of catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD); additionally, expression levels of 3-nitrotyrosine (3-NT), 4-hydroxynonenal (4-HNE), and oxidized protein (OP) were quantified. Whole glomerular filtration rate (GFR) was measured. Urinary excretion of neutrophil gelatinase-associated lipocalin (uNGAL), osteopontin (uOPN), and N-acetyl-ß-D-glucosaminidase (uNAG) was also determined. RESULTS: Diabetic rats showed an increase in uNGAL excretion 7 days following induction of diabetes. Diuresis, proteinuria, albuminuria, creatinine clearance, and GFR were significantly increased by 30 days after induction. Furthermore, there was an increase in both CAT and SOD activity, in addition to 3-NT, 4-HNE, and OP expression levels. However, GPx activity was lower. Serum levels of NGAL and OPN, as well as excretion levels of uNGAL, uOPN, and uNAG, were increased in diabetics. Tubular damage was observed by 7 days after diabetes induction and was further aggravated by 30 days after induction. CONCLUSION: The tubular dysfunction evidenced by urinary excretion of NGAL precedes oxidative stress during diabetes.

Papel da lipocalina associada à gelatinase neutrofílica (NGAL) urinária na nefrotoxicidade da cisplatina em pacientes com câncer de cabeça e pescoço / Evaluation of the cisplatin nephrotoxicity using the urinary neutrophil gelatinase-associated lipocalin (NGAL) in patients with head and neck cancer

Introdução: A injúria renal aguda (IRA) em pacientes que recebem a cisplatina é comum, portanto, a avaliação da função renal em pacientes utilizando drogas nefrotóxicas é fundamental. Objetivo: Avaliar a incidência da IRA e o papel da lipocalina associada à gelatinase neutrofílica (NGAL) na avaliação da função renal em pacientes com câncer de cabeça e pescoço (CCP) que receberam a cisplatina. Métodos: Foram avaliados prospectivamente 50 pacientes com CCP, tratados com três sessões de cisplatina. Foram coletados sangue e urina 24 horas antes da cisplatina, 24 horas após a infusão, 48 horas após cada aplicação e 35 dias após o término do tratamento (NGAL urinária, proteína C reativa, creatinina e taxa de filtração glomerular, desidrogenase lática e magnésio plasmáticos). Resultados: A IRA foi observada em 78% dos pacientes. Houve aumento na creatinina, ureia e queda na TFG após cada ciclo de cisplatina, e aumento da NGAL urinária. Foi observada associação positiva entre os níveis de NGAL e a creatinina e PCR. Evidenciou-se um aumento dos níveis de creatinina, NGAL, PCR e diminuição da TFG nos pacientes com IRA em relação aos pacientes sem IRA. Conclusão: Observamos IRA em 78% dos pacientes avaliados com CCP tratados com a cisplatina e correlação da NGAL com a creatinina e a TFG em demonstrar lesão renal. Os níveis de NGAL podem estar elevados em relação aos níveis basais, mesmo antes da utilização da cisplatina. .

Introduction: Acute kidney injury (AKI) in patients receiving cisplatin is common, therefore the evaluation of renal function in patients on use of nephrotoxic drugs is fundamental. Objective: To evaluate the incidence of AKI and the role of lipocalin associated to neutrophil gelatinase (NGAL) in the monitoring of renal function in patients with head and neck cancer (HNC) who received cisplatin. Methods: We prospectively studied 50 patients with HNC treated with three sessions of cisplatin. Blood and urine were collected 24 hours before cisplatin, 24 hours after infusion, 48 hours after each application and 35 days after the end of treatment (urine NGAL, C-reactive protein, creatinine, glomerular filtration rate, plasma lactate dehydrogenase and magnesium). Results: AKI was observed in 78% of patients. There was increase in creatinine, and decrease in GFR after each cycle of cisplatin, and increased urine NGAL. Positive association was observed between the levels of NGAL, creatinine and C-reactive protein. It was observed an increase in creatinine, NGAL, C-reactive protein and decreased GFR in AKI patients compared to patients without AKI. Conclusion: AKI was noted in 78% of patients with HNC treated with cisplatin and showed the correlation of NGAL with creatinine and GFR in demonstrating renal injury. NGAL levels may be elevated compared to baseline levels, even before the use of cisplatin. .

Tubular urinary biomarkers do not identify aetiology of acute kidney injury in kidney transplant recipients.

AIM: To evaluate the performance of urinary neutrophil gelatinase-associated lipocalin (uNGAL), kidney injury molecule, interleukin-18 and heat shock protein 72 for differential diagnosis between causes of acute kidney injury in kidney transplant recipients, especially immunological rejection. PATIENTS AND METHODS: We measured these biomarkers in 67 kidney transplant recipients with acute kidney injury according to the RIFLE criteria. RESULTS: There were no statistical differences in biomarkers between kidney transplant recipients with immunological rejection (n = 20), pre-renal causes (n = 20) and other AKI causes (n = 27). Only the uNGAL level relative to urinary creatinine (uNGAL/uCr) for immunological rejection was different in comparison with others (P < 0.001); a cut-off of 59 µg/g of uNGAL/uCr had a sensitivity and specificity of 60% and 58% respectively (area under the curve in receiver-operating characteristic curve, 0.65). The other biomarkers were not useful in differentiating the causes of acute kidney injury. CONCLUSION: The biomarkers tested are not useful in identifying immunological rejection as cause of acute kidney injury in kidney transplant recipients.

Effects of Schizolobium parahyba extract on experimental Bothrops venom-induced acute kidney injury.

BACKGROUND: Venom-induced acute kidney injury (AKI) is a frequent complication of Bothrops snakebite with relevant morbidity and mortality. The aim of this study was to assess the effects of Schizolobium parahyba (SP) extract, a natural medicine with presumed anti-Bothrops venom effects, in an experimental model of Bothrops jararaca venom (BV)-induced AKI. METHODOLOGY: Groups of 8 to 10 rats received infusions of 0.9% saline (control, C), SP 2 mg/kg, BV 0.25 mg/kg and BV immediately followed by SP (treatment, T) in the doses already described. After the respective infusions, animals were assessed for their glomerular filtration rate (GFR, inulin clearance), renal blood flow (RBF, Doppler), blood pressure (BP, intra-arterial transducer), renal vascular resistance (RVR), urinary osmolality (UO, freezing point), urinary neutrophil gelatinase-associated lipocalin (NGAL, enzyme-linked immunosorbent assay [ELISA]), lactate dehydrogenase (LDH, kinetic method), hematocrit (Hct, microhematocrit), fibrinogen (Fi, Klauss modified) and blinded renal histology (acute tubular necrosis score). PRINCIPAL FINDINGS: BV caused significant decreases in GFR, RBF, UO, HcT and Fi; significant increases in RVR, NGAL and LDH; and acute tubular necrosis. SP did not prevent these changes; instead, it caused a significant decrease in GFR when used alone. CONCLUSION: SP administered simultaneously with BV, in an approximate 10∶1 concentration, did not prevent BV-induced AKI, hemolysis and fibrinogen consumption. SP used alone caused a decrease in GFR.

Urinary NGAL in patients with and without acute kidney injury in a cardiology intensive care unit.

OBJECTIVE: To assess the diagnostic and prognostic efficacy of urine neutrophil gelatinase-associated lipocalin in patients admitted to an intensive care unit. METHODS: Longitudinal, prospective cohort study conducted in a cardiology intensive care unit. The participants were divided into groups with and without acute kidney injury and were followed from admission to the intensive care unit until hospital discharge or death. Serum creatinine, urine output and urine neutrophil gelatinase-associated lipocalin were measured 24 and 48 hours after admission. RESULTS: A total of 83 patients admitted to the intensive care unit for clinical reasons were assessed, most being male (57.8%). The participants were divided into groups without acute kidney injury (N=18), with acute kidney injury (N=28) and with severe acute kidney injury (N=37). Chronic diseases, mechanical ventilation and renal replacement therapy were more common in the groups with acute kidney injury and severe acute kidney injury, and those groups exhibited longer intensive care unit stay and hospital stay and higher mortality. Serum creatinine did not change significantly in the group with acute kidney injury within the first 24 hours of admission to the intensive care unit, although, urine neutrophil gelatinase-associated lipocalin was high in the groups with acute kidney injury and severe acute kidney injury (p<0.001). Increased urine neutrophil gelatinase-associated lipocalin was associated with death. CONCLUSION: An increase in urine neutrophil gelatinase-associated lipocalin precedes variations in serum creatinine in patients with acute kidney injury and may be associated with death.

Urinary exosomes as a source of kidney dysfunction biomarker in renal transplantation.

End-stage renal disease (ESRD) requires for its treatment permanent dialysis or kidney transplantation (KT). KT is the best clinical treatment, however, the early function of the allograft varies depending on multiple factors associated with cold ischemia time (CIT) and the allograft rejection process. It is known that serum creatinine is an insensitive and late marker for predicting graft recovery after KT, mainly in patients with delayed graft function (DGF). Neutrophil gelatinase-associated lipocalin (NGAL) is produced in the distal nephron and it is one of the most promising novel biomarkers for acute kidney injury (AKI) and chronic kidney disease (CKD). NGAL has been proposed to be a predictor of organ recovery from DGF after KT from donors after cardiac death. Because nonrenal diseases can also induce NGAL, more information is necessary to validate the sensitivity and specificity of urine and plasma NGAL in clinical samples. The exosomes are vesicles released into the urine from the kidney epithelium and they have been proposed as better source to explore as biomarker of renal dysfunction. The molecular composition of the urinary exosomes could be representative of the physiological or physiopathologic condition of the urinary system. We propose that determination of NGAL in urinary exosomes is a better predictor of kidney dysfunction after KT than other urinary fractions. We analyzed 15 kidney allograft recipients, with a mean age of 36 years (range, 16-60 years) and 75% were male: 11 living donors (LD) and 4 deceased donors (DD). The average length of CIT was 14 hours in DD and less than 1 hour in LD. Three patient developed DGF. Using Western blot analysis, NGAL was detectable in the cellular and exosomal fraction of the urine. The exosomes expressed higher levels of NGAL than the cellular fraction. The expression of NGAL was observed from the first day after transplantation. In the cellular fraction of the urine, no significant differences of NGAL were observed between the patients. However, the median of NGAL expression in the exosomes fraction was significantly higher in DD patient, from the first day after KT (P < .05). Moreover, we noticed that NGAL expression in exosomes remained elevated in the patients with DGF compared with non-DGF patients (P < .05). Considering the highest abundance of NGAL in the urinary exosomes and its correlation with DGF patients, we suggest the exosomal fraction as a more sensitive substrate to evaluate early biomarkers of DGF after KT.

Are recently reported biomarkers helpful for early and accurate diagnosis of acute kidney injury?

Over the past few years and with the use of innovative genomic and proteomic tools, several molecules that their urinary concentration is modified during acute kidney injury have been identified and proposed as biomarkers. Among the most studied biomarkers are neutrophil gelatinase-associated lipocalin-2, kidney injury molecule-1, interleukin-18, cystatin C, N-acetyl-ß-D-glucosaminidase, liver fatty-acid binding protein, and heat shock protein 72. Here, we reviewed and compared the sensitivity and specificity of each biomarker for the appropriate diagnosis of acute kidney injury, as well as its ability to stratify renal injury and to monitor a renoprotective pharmacologic strategy.

Urine biomarkers predict acute kidney injury in newborns.

OBJECTIVE: To identify urine biomarkers predictive of acute kidney injury (AKI) in infants admitted to level 2 and 3 neonatal intensive care units with birth weight >2000 g and 5-minute Apgar score ≤ 7. STUDY DESIGN: A nested case-control study was performed comparing 8 candidate urine AKI biomarkers in infants with AKI (defined as a rise in serum creatinine of at least 0.3 mg/dL or a serum creatinine elevation ≥ 1.7 mg/dL persisting for 3 days) and 24 infants from the described cohort without AKI. Urine was analyzed for neutrophil gelatinase-associated lipocalin, osteopontin, cystatin C, albumin, ß(2) microglobulin, epithelial growth factor, uromodulin (UMOD), and kidney injury molecule 1. RESULTS: Compared with the infants without AKI, those with AKI had higher levels of urine cystatin C (1123 pg/mL [95% CI, 272-4635 pg/mL] vs 90 pg/mL [95% CI, 39-205 pg/mL]; P < .004; area under the receiver operating characteristic curve [AUC] = 0.82), lower levels of UMOD (11.0 pg/mL [95% CI, 5.7-21.4 pg/mL] vs 26.2 pg/mL [95% CI, 17.4-39.4 pg/mL]; P < .03; AUC = 0.77), and lower levels of epithelial growth factor (6.7 pg/mL [95% CI, 4.0-11.3 pg/mL] vs 17.4 pg/mL [95% CI, 12.7-23.8 pg/mL; P = .003; AUC = 0.82). Although the differences were not statistically significant, levels of urine neutrophil-associated gelatinase lipocalin, kidney injury molecule 1, and osteopontin trended higher in infants with AKI. CONCLUSION: Urinary biomarkers can predict AKI in neonates admitted to level 2 and 3 neonatal intensive care units.

Neutrophil gelatinase-associated lipocalin: a novel biomarker in acute kidney injury.

Acute kidney injury (AKI) is a frequent complication in critically ill patients and is associated with high morbidity and mortality; therefore, its prophylaxis, diagnosis and intervention positively impact patient evolution. Neutrophil gelatinase-associated lipocalin (NGAL) or lipocalin, a protein synthesized by renal tubular cells, has the property to transport lipophilic molecules such as vitamins, hormones and antigenic agents. It is a novel biomarker of AKI of several etiologies and is increased in both serum and urine 48 h before the increase of creatinine. It has a strong correlation with early diagnosis of AKI. NGAL is of the most investigated and promising biomarkers for early diagnosis of AKI in different clinical scenarios, most notably in sepsis, cardiorenal syndrome, cardiac surgery, kidney transplant, contrast nephropathy and hemolytic uremic syndrome. Lipocalin guides the early institution of therapeutic interventions to improve prognosis in AKI of several etiologies.

Neutrophil gelatinase-associated lipocalin concentrations predict development of acute kidney injury in neonates and children after cardiopulmonary bypass.

OBJECTIVES: To investigate neutrophil gelatinase-associated lipocalin (NGAL) as an early acute kidney injury (AKI) biomarker after neonatal and pediatric cardiopulmonary bypass (CPB). STUDY DESIGN: Serum and urine samples were obtained before and at intervals after CPB from 374 patients. AKI was defined as a serum creatinine (S(Cr)) concentration increase from baseline ≥0.3 mg/dL in neonates and ≥50% in children within 48 hours of CPB. Logistic regression was used to assess predictors and clinical outcomes associated with AKI. RESULTS: AKI developed in 30% of patients. Plasma and urine NGAL thresholds significantly increased in patients with AKI at 2 hours after CPB and remained elevated at all points, with 2-hour NGAL the earliest, strongest predictor of AKI. In non-neonates, 2-hour plasma and urine NGAL thresholds strongly correlated with length of hospital stay and severity and duration of AKI. CONCLUSION: Plasma and urine NGAL thresholds are early predictive biomarkers for AKI and its clinical outcomes after CPB. In neonates, we recommend a 2-hour plasma NGAL threshold of 100 ng/mL and 2-hour urine NGAL threshold of 185 ng/mL for diagnosis of AKI. In non-neonates, recommended AKI thresholds are 50 ng/mL for both 2-hour plasma and urine NGAL.

Hsp72 is an early and sensitive biomarker to detect acute kidney injury.

This study was designed to assess whether heat shock protein Hsp72 is an early and sensitive biomarker of acute kidney injury (AKI) as well as to monitor a renoprotective strategy. Seventy-two Wistar rats were divided into six groups: sham-operated and rats subjected to 10, 20, 30, 45 and 60 min of bilateral ischemia (I) and 24 h of reperfusion (R). Different times of reperfusion (3, 6, 9, 12, 18, 24, 48, 72, 96 and 120 h) were also evaluated in 30 other rats subjected to 30 min of ischemia. Hsp72 messenger RNA (mRNA) and protein levels were determined in both kidney and urine. Hsp72-specificity as a biomarker to assess the success of a renoprotective intervention was evaluated in rats treated with different doses of spironolactone before I/R. Renal Hsp72 mRNA and protein, as well as urinary Hsp72 levels, gradually increased relative to the extent of renal injury induced by different periods of ischemia quantified by histomorphometry as a benchmark of kidney damage. Urinary Hsp72 increased significantly after 3 h and continued rising until 18 h, followed by restoration after 120 h of reperfusion in accord with histopathological findings. Spironolactone renoprotection was associated with normalization of urinary Hsp72 levels. Accordingly, urinary Hsp72 was significantly increased in patients with clinical AKI before serum creatinine elevation. Our results show that urinary Hsp72 is a useful biomarker for early detection and stratification of AKI. In addition, urinary Hsp72 levels are sensitive enough to monitor therapeutic interventions and the degree of tubular recovery following an I/R insult.