Neutrophil Gelatinase-Associated Lipocalin Is a New and Sensitive Marker of Kidney Function in Chronic Kidney Disease Patients and Renal Allograft Recipients

Urinary neutrophil gelatinase-associated lipocalin levels in comparison with glomerular filtration rate for evaluation of renal function in patients with diabetic chronic kidney disease

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker of acute kidney injury. There is a growing body of evidence suggesting that NGAL is also a marker of kidney disease and severity in chronic kidney disease (CKD). We studied the utility of urinary NGAL in more accurately predicting renal function in patients with diabetic CKD.

METHODS

We studied possible relationships between urinary NGAL, estimated glomerular filtration rate (eGFR), and proteinuria in diabetic CKD patients and in healthy populations.

RESULTS

Urinary NGAL levels were significantly higher in CKD patients than in healthy controls (96.0 [2.7 to 975.2] ng/mL vs. 18.8 [1.3 to 81.9] ng/mL, P=0.02), and the GFR was lower among CKD patients (49.3 [13.1 to 78.3] mL/min/1.73 m(2) vs. 85.6 [72 to 106.7] mL/min/1.73 m(2), P<0.0001). The urinary NGAL level showed a significant inverse correlation with GFR (r=-0.5634, P<0.0001). The correlation analyses between urinary protein level and urinary NGAL levels and GFR were as follows: urine protein and urinary NGAL (r=0.3009, P=0.0256), urine protein and GFR (r=-0.6245, P<0.0001), urine microalbumin and urinary NGAL (r=0.1794, P=0.2275), and urine microalbumin and GFR (r=-0.5190, P=0.0002).

CONCLUSION

From these results, we concluded that urinary NGAL is a reliable marker of renal function in diabetic CKD patients. However, urinary NGAL did not provide more accurate information regarding renal function than GFR.

Renal biomarkers for assessment of kidney function in renal transplant recipients: how do they compare?

Accurate assessment of renal function is of key importance, given its prognostic value. However, gold standard measures are cumbersome, and serum creatinine itself is an insensitive predictor, especially in renal transplant recipients. Though GFR-estimating formulae have been relied upon, they do have their own limitations. Nevertheless, renal biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C, among others, are now emerging as potentially useful indicators of GFR. We aimed to evaluate the diagnostic performance of NGAL versus cystatin C and eGFR using CKD-EPI, MDRD and cystatin C in renal transplant recipients and non-transplant CKD patients. We found a significant correlation between NGAL, serum creatinine, cystatin C and eGFR. The latter parameters were also strong predictors of serum NGAL levels. However, performance of NGAL, based on receiver operating characteristic curves, was inferior to that of the reference tests. It appears that in renal transplant recipients NGAL correlates well with cystatin C and eGFR, most strongly with cystatin-based formula. Though this suggests potential use of NGAL as a screening test, its weaker diagnostic performance raises some concern about its clinical usefulness. Larger studies are needed to explore this further.

Neutrophil gelatinase-associated lipocalin (NGAL) in inflammatory bowel disease: association with pathophysiology of inflammation, established markers, and disease activity

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) is a multi-potent 25-kDa protein mainly secreted by neutrophils. In inflammatory bowel disease (IBD), overexpression of NGAL in colon epithelium has been previously shown. This is the first study analyzing serum and urinary NGAL levels in IBD patients, with regard to specific characteristics of patients and disease.

METHODS

Serum and urinary NGAL levels were determined in 181 patients with IBD, 93 with ulcerative colitis (UC), and 88 with Crohn's disease (CD), 82 healthy controls (HC), and 41 patients with irritable bowel syndrome (IBS).

RESULTS

Serum NGAL levels were elevated in IBD patients (88.19 ± 40.75 ng/mL) compared with either HC (60.06 ± 24.18 ng/mL) or IBS patients (60.80 ± 20.30 ng/mL), P < 0.0001. No significant difference was shown between UC (86.62 ± 35.40 ng/mL) and CD (89.92 ± 46.05 ng/mL). Significantly higher levels of serum NGAL were observed in patients with active (120.1 ± 38.46) versus inactive IBD (61.58 ± 15.98), P < 0.0001. Serum NGAL displayed a strong ability to distinguish active IBD from inactive disease, healthy controls, or IBS patients with a sensitivity of 100, 95, and 95% and a specificity of 68, 83, and 79%, respectively, performing better than erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) in the assessment of disease activity in both UC and CD. Urinary NGAL levels showed neither significant difference among patients and controls nor correlation with disease activity.

CONCLUSIONS

Serum NGAL is elevated particularly in active IBD and correlates with established markers of inflammation and disease activity, implicating its role in the pathophysiology of IBD.

Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule 1 (KIM-1) as predictors of incident CKD stage 3: the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Identifying individuals at risk of chronic kidney disease (CKD) is critical for timely treatment initiation to slow progression of the disease. Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule 1 (KIM-1) are known biomarkers of acute kidney injury, but it is unknown whether these markers are associated with incident CKD stage 3 in the general population.

STUDY DESIGN

Matched case-control study.

SETTING & PARTICIPANTS

African American and white participants from the Atherosclerosis Risk in Communities (ARIC) Study who at baseline had an estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m(2) and urinary albumin-creatinine ratio ≤30 mg/g. 143 controls were matched for age, sex, and race to 143 cases of incident CKD stage 3 after 8.6 years of follow-up.

PREDICTORS

Quartile of NGAL and KIM-1.

OUTCOMES & MEASUREMENTS

Incident CKD stage 3 (eGFR <60 mL/min/1.73 m(2) at follow-up and a decrease in eGFR from baseline to follow-up ≥25%).

RESULTS

Both NGAL (P = 0.05) and KIM-1 levels (P < 0.001) were correlated positively with baseline urinary albumin-creatinine ratio; neither was associated with baseline eGFR. Participants with NGAL concentrations in the fourth quartile had more than 2-fold higher odds (adjusted OR, 2.11; 95% CI, 0.96-4.64) of incident CKD stage 3 compared with participants in the first quartile after multivariable adjustment (P-trend = 0.03). Adjustment for urinary creatinine and albumin levels resulted in a nonsignificant association (highest quartile adjusted OR, 1.52; 95% CI, 0.64-3.58; P = 0.2). No significant association between KIM-1 level and incident CKD was observed in crude or adjusted models.

LIMITATIONS

The relatively small sample size of the study limits precision and power to detect weak associations.

CONCLUSIONS

Higher NGAL, but not KIM-1, levels were associated with incident CKD stage 3. Adjustment for urinary creatinine and albumin concentration attenuated this association. Additional studies are needed to confirm these findings and assess the utility of urinary NGAL as a marker of CKD risk.

Novel insights into the relationship between glomerular pathology and progressive kidney disease

Both glomerular and tubulointerstitial damage are important factors in the pathophysiology and progression of nephropathy. Glomerular injury is associated with tubulointerstitial inflammation, and many studies show that tubulointerstitial changes correlate well with progressive renal functional decline. Strong evidence supports the concept that once established, proteinuric glomerular injury can cause tubular injury. This review briefly summarizes the pathophysiological consequences of glomerular damage that are responsible for tubulointerstitial injury. It further focuses on tubule-derived renal injury biomarkers that may be used to monitor the progression of kidney disease. This monitoring is predicted to become increasingly useful as novel therapeutic interventions preventing progressive renal damage are introduced. In particular, biomarkers of kidney dysfunction, such as urinary podocytes, kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, hematopoietic growth factor-inducible neurokinin 1, or periostin, might be useful in the diagnosis or detection of early nephropathy and risk assessment of kidney disease. However, these biomarkers require further study before they are used in routine screening or in guiding patient therapy.

Neutrophil gelatinase-associated lipocalin (NGAL) as biomarker of acute kidney injury: a review of the laboratory characteristics and clinical evidences

Acute kidney injury (AKI) is a common and serious condition, currently diagnosed by functional biomarkers, such as serum creatinine measurements. Unfortunately, creatinine increase is a delayed and unreliable indicator of AKI. The lack of early biomarkers of structural kidney injury has hampered our ability to translate promising experimental therapies to human AKI. The recent discovery, translation and validation of neutrophil gelatinase-associated lipocalin (NGAL), possibly the most promising novel AKI biomarker, is reviewed here. NGAL may be measured by several methods both in plasma and urine for the early diagnosis of AKI and for the prediction of clinical outcomes, such as dialysis requirement and mortality, in several common clinical scenarios, including in the intensive care unit, cardiac surgery and renal damage due the exposition to toxic agent and drugs, and renal transplantation. Furthermore, the predictive properties of NGAL, may play a critical role in expediting the drug development process. A systematic review of literature data indicates that further studies are necessary to establish accurate reference population values according to age, gender and ethnicity, as well as reliable and specific decisional values concerning the more common clinical settings related to AKI. Furthermore, proper randomized clinical trials on renal and systemic outcomes comparing the use of NGAL vs. standard clinical practice are still lacking and accurate cost-benefit and/or cost-utility analyses for NGAL as biomarker of AKI are also needed. However, it is important to note that NGAL, in the absence of diagnostic increases in serum creatinine, is able to detect some patients affected by subclinical AKI who have an increased risk of adverse outcomes. These results also suggest that the concept and definition of AKI might need to be reassessed.

Plasma neutrophil gelatinase associated lipocalin (NGAL) is associated with kidney function in uraemic patients before and after kidney transplantation

Background

Neutrophil gelatinase associated lipocalin (NGAL) is a biomarker of kidney injury. We examined plasma levels of NGAL in a cohort of 57 kidney allograft recipients (Tx group, 39 ± 13 years), a uraemic group of 40 patients remaining on the waiting list (47 ± 11 years) and a control group of 14 healthy subjects matched for age, sex and body mass index (BMI). The kidney graft recipients were studied at baseline before transplantation and 3 and 12 months after transplantation and the uraemic group at baseline and after 12 months.

Methods

NGAL was measured using a validated in-house Time-Resolved Immuno-flourometric assay (TRIFMA). Repeated measurements differed by < 10% and mean values were used for statistical analyses. Spearman rank order correlation analysis and the Kruskal-Wallis non-parametric test were used to evaluate the association of NGAL concentrations with clinical parameters.

Results

Plasma NGAL levels before transplantation in the Tx and uraemic groups were significantly higher than in the healthy controls (1,251 μg/L, 1,478 μg/L vs. 163 μg/L, p < 0.0001). In the Tx group NGAL concentrations were associated with serum creatinine (R = 0.51, p < 0.0001), duration of end-stage renal failure (R = 0.41, p = 0.002) and leukocyte count (R = 0.29, p < 0.026). At 3 and 12 months plasma NGAL concentrations declined to 223 μg/L and 243 μg/L, respectively and were associated with homocysteine (R = 0.39, p = 0.0051 and R = 0.47, p = 0.0007).

Conclusions

Plasma NGAL is a novel marker of kidney function, which correlates to duration of end-stage renal failure (ESRD) and serum creatinine in uraemic patients awaiting kidney transplantation. Plasma NGAL is associated with homocysteine in transplanted patients. The prognostic value of these findings requires further studies.

Cystatin C and neutrophil gelatinase-associated lipocalin as markers of renal function in pediatric heart transplant recipients

We hypothesized that use of Schwartz formula underestimates the prevalence of CKD in PHT recipients. This study determined the prevalence and risk factors for CKD in PHT using novel methods-serum cystatin C, CKiD formula, Revised Schwartz formula, s- and u-NGAL. Serum BUN, creatinine, cystatin C and s- and u-NGAL were measured after prospective enrollment. Schwartz formula GFR was compared with novel methods. CKD was defined as CKiD GFR < 90 mL/min/1.73 m(2) . The s- and u-NGAL were compared between those with and without CKD. Potential risk factors for CKD were analyzed. Seventy-nine patients (46 male children or boys), mean age 9.9 ± 5.8 yr formed the study cohort. The prevalence of mild and moderate CKD was 2- to 3-fold higher using novel methods compared to Schwartz formula. u-NGAL and u-NGAL/Cr were significantly higher in patients with CKD. u- and s-NGAL had negative correlation with estimates of GFR. Women were at a higher risk for CKD (odds ratio 8.7) as was longer duration since transplant (p = 0.009). In conclusion, use of novel methods of GFR estimation unmasked 2- to 3-fold increased prevalence of CKD in PHT. Women and those with longer duration since transplant are at higher risk for CKD.

Neutrophil gelatinase-associated lipocalin (NGAL) as a biomarker for early acute kidney injury

Based on information to date, although limitations in the accuracy of NGAL in predicting AKI persist, the preponderance of published studies demonstrate that NGAL, when measured in the plasma and in the urine, is a reliable biomarker for the subsequent development of clinically apparent AKI. If very early detection of AKI, via the measurement of plasma or urinary NGAL, can be followed by effective treatment to abort the development or limit the severity of AKI, and therefore decrease the rate of RRT, length of hospitalization stay, and/or mortality risk, NGAL measurement will become a critically important diagnostic tool in critical care medicine, pediatrics, and surgery.

Markers of kidney function in the elderly in relation to the new CKD-EPI formula for estimation of glomerular filtration rate

INTRODUCTION

Neutrophil gelatinase-associated lipocalin (NGAL) has been recently proved useful in the quantitation of chronic kidney disease (CKD). The aim of the study was to assess prevalence of CKD according to the Modification of Diet in Renal Disease (MDRD), Cockcroft-Gault, and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formulae in 412 patients with normal serum creatinine and markers of kidney function/injury such as NGAL, cystatin C, and kidney injury molecule-1 (KIM-1) in these patients in relation to age (below and over 65 years).

MATERIAL AND METHODS

We included in the study 1005 patients with coronary artery disease and normal serum creatinine. However, markers of kidney function/injury were assessed in 412 patients. The NGAL, cystatin C and KIM-1, were assessed using commercially available kits.

RESULTS

Patients over 65 years had significantly lower estimated glomerular filtration rate (eGFR) than their younger counterparts despite identical creatinine. They also had significantly lower haematocrit, despite similar Hb, lower platelet count, higher serum fibrinogen, higher systolic (SBP) and lower diastolic blood pressure, higher serum NGAL and cystatin C, but similar urinary NGAL and KIM-1. Serum NGAL correlated with age, haematocrit, leukocyte, platelet and erythrocyte count, eGFR, creatinine, fasting glucose, HbA(1c), fibrinogen, SBP, and diabetes duration. In multiple regression analysis kidney function (eGFR, creatinine clearance or creatinine), cystatin C and SBP were predictors of serum NGAL.

CONCLUSIONS

In our study we found a very high prevalence of CKD up to 61% in elderly patients with coronary artery disease and normal serum creatinine. Neutrophil gelatinase-associated lipocalin could be a sensitive marker of kidney function, particularly in elderly patients with another risk factor for kidney damage, i.e. hypertension.

Biomarkers in chronic kidney disease: a review

Chronic kidney disease (CKD) is a major public health problem. The classification of CKD by KDOQI and KDIGO and the routine eGFR reporting have resulted in increased identification of CKD. It is important to be able to identify those at high risk of CKD progression and its associated cardiovascular disease (CVD). Proteinuria is the most sensitive marker of CKD progression in clinical practice, especially when combined with eGFR, but these have limitations. Hence, early, more sensitive, biomarkers are required. Recently, promising biomarkers have been identified for CKD progression and its associated CVD morbidity and mortality. These may be more sensitive biomarkers of kidney function, the underlying pathophysiological processes, and/or cardiovascular risk. Although there are some common pathways to CKD progression, there are many primary causes, each with its own specific pathophysiological mechanism. Hence, a panel measuring multiple biomarkers including disease-specific biomarkers may be required. Large, longitudinal observational studies are needed to validate candidate biomarkers in a broad range of populations prior to implementation into routine CKD management. Recent renal biomarkers discovered include neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, and liver-type fatty acid-binding protein. Although none are ready for use in clinical practice, it is timely to review the role of such biomarkers in predicting CKD progression and/or CVD risk in CKD.

A systematic analysis of the effects of increasing degrees of serum immunodepletion in terms of depth of coverage and other key aspects in top-down and bottom-up proteomic analyses

Immunodepletion of clinical fluids to overcome the dominance by a few very abundant proteins has been explored but studies are few, commonly examining only limited aspects with one analytical platform. We have systematically compared immunodepletion of 6, 14, or 20 proteins using serum from renal transplant patients, analysing reproducibility, depth of coverage, efficiency, and specificity using 2-D DIGE (‘top-down’) and LC-MS/MS (‘bottom-up’). A progressive increase in protein number (≥2 unique peptides) was found from 159 in unfractionated serum to 301 following 20 protein depletion using a relatively high-throughput 1-D-LC-MS/MS approach, including known biomarkers and moderate–lower abundance proteins such as NGAL and cytokine/growth factor receptors. On the contrary, readout by 2-D DIGE demonstrated good reproducibility of immunodepletion, but additional proteins seen tended to be isoforms of existing proteins. Depletion of 14 or 20 proteins followed by LC-MS/MS showed excellent reproducibility of proteins detected and a significant overlap between columns. Using label-free analysis, greater run-to-run variability was seen with the Prot20 column compared with the MARS14 column (median %CVs of 30.9 versus 18.2%, respectively) and a corresponding wider precision profile for the Prot20. These results illustrate the potential of immunodepletion followed by 1-D nano-LC-LTQ Orbitrap Velos analysis in a moderate through-put biomarker discovery process.

Protein microarrays discover angiotensinogen and PRKRIP1 as novel targets for autoantibodies in chronic renal disease

Biomarkers for early detection of chronic kidney disease are needed, as millions of patients suffer from chronic diseases predisposing them to kidney failure. Protein microarrays may also hold utility in the discovery of auto-antibodies in other conditions not commonly considered auto-immune diseases. We hypothesized that proteins are released as a consequence of damage at a cellular level during end-organ damage from renal injury, not otherwise recognized as self-antigens, and an adaptive humoral immune response to these proteins might be detected in the blood, as a noninvasive tracker of this injury. The resultant antibodies (Ab) detected in the blood would serve as effective biomarkers for occult renal injury, enabling earlier clinical detection of chronic kidney disease than currently possible, because of the redundancy of the serum creatinine as a biomarker for early kidney injury. To screen for novel autoantibodies in chronic kidney disease, 24 protein microarrays were used to compare serum Ab from patients with chronic kidney disease against matched controls. From a panel of 38 antigens with increased Ab binding, four were validated in 71 individuals, with (n=50) and without (n=21) renal insufficiency. Significant elevations in the titer of novel auto-Ab were noted against angiotensinogen and PRKRIP1 in renal insufficiency. Current validation is underway to evaluate if these auto-Ab can provide means to follow the evolution of chronic kidney disease in patients with early stages of renal insufficiency, and if these rising titers of these auto-Ab correlate with the rate of progression of chronic kidney disease.

Neutrophil gelatinase-associated lipocalin (NGAL): a new marker of cyclosporine nephrotoxicity?

The aim of work was to investigate whether serum and urinary neutrophil gelatinase-associated lipocalin(sNGAL and uNGAL, respectively) are potential biomarkers of early cyclosporine A (CsA) nephrotoxicity in steroid-dependent nephrotic children (SDNS). The study group (I) consisted of 19 children with SDNS aged 9.46+/-5.52 years treated with CsA. The children were examined four times: at proteinuria relapse, prior to CsA treatment,then after 3, 6, and 12 months of CsA treatment. The control group (II) consisted of 18 healthy children aged 3-15 years. A commercial enzyme-linked immunosorbent assay method was used to measure NGAL concentration.The sNGAL level in SDNS children prior to the administration of CsA was similar to that in the healthy controls (p>0.05), but it increased significantly during the course of treatment (p<0.01). The uNGAL/creatinine (cr) ratio in SDNS patients was higher before the withdrawal of CsA therapy (p<0.05), and was also increased at the consecutive examinations (p<0.01). There was a positive correlation between both sNGAL and uNGAL levels and CsA serum level. However, based on the serum and urinary NGAL/cr receiver operating characteristic curve and area under the curve (AUC) analysis, it remains uncertain whether uNGAL is a good predictor of cyclosporine nephropathy. Both sNGAL and uNGAL concentrations increased during the course of CsA treatment. Further studies in larger groups of patients are therefore necessary to confirm our experimental data that increased NGAL levels may be a non-invasive marker for the early detection of tubulointerstitial damage in CsA nephrotoxicity.

NGAL (neutrophil gelatinase-associated lipocalin) and L-FABP after percutaneous coronary interventions due to unstable angina in patients with normal serum creatinine

PURPOSE

The value of NGAL (neutrophil gelatinase-associated lipocalin) and L-FABP (liver-type fatty acid binding protein) has been highlighted as a novel biomarker of detection of acute renal failure in children after cardiac surgery. Interventional cardiologists are being asked more frequently to perform percutaneous coronary intervention (PCI) and contrast nephropathy is its potentially serious complication. We aimed to prospectively assess NGAL and L-FABP in patients with normal serum creatinine undergoing PCI due to unstable angina.

MATERIAL AND METHODS

We measured serum NGAL, urinary NGAL and L-FABP using commercially available kits before and after 2, 4, 12, 24 and 48 hours following PCI in 25 patients.

RESULTS

We found a significant rise in serum NGAL after 2 and 4 hours. Urinary NGAL and urinary L-FABP followed the same pattern. Both markers increased significantly after 4 hours and remained elevated up to 48 hours after PCI. Serum creatinine did not change significantly during the study period.

CONCLUSIONS

NGAL and L-FABP may represent a sensitive early biomarkers of renal impairment after PCI. Persistently increased urinary NGAL and L-FABP may suggest renotubular damage in this population.

Urinary neutrophil gelatinase-associated lipocalin as a novel biomarker for disease activity in lupus nephritis

OBJECTIVES

Clinical and laboratory markers in current use have limited specificity and sensitivity for predicting the development of renal disease in lupus patients. In this longitudinal study, we investigated whether urinary neutrophil gelatinase-associated lipocalin (uNGAL) predicts active nephritis and renal flares in lupus patients with and without a history of biopsy-proven lupus nephritis.

METHODS

Renal disease activity and flare status was determined by SLEDAI and BILAG scores. Random effects models were used to determine whether uNGAL was a significant predictor for renal disease activity in SLE patients, and for renal flares in patients with established nephritis. To assess the predictive performance of uNGAL, receiver operating characteristic (ROC) curves were constructed using the previous visit's uNGAL level. These curves were then compared with curves constructed with currently used biomarkers. Cut-offs determined by ROC curves were tested in an independent validation cohort.

RESULTS

uNGAL was found to be a significant predictor of renal disease activity in all SLE patients, and a significant predictor for flare in patients with a history of biopsy-proven nephritis, in multivariate models adjusting for age, race, sex and anti-double-stranded (ds)DNA antibody titres. As a predictor of renal flare in patients with biopsy-proven nephritis, uNGAL outperformed anti-dsDNA antibody titres. These results were confirmed in an independent validation cohort.

CONCLUSIONS

uNGAL predicts renal flare in patients with a history of biopsy-proven nephritis with high sensitivity and specificity. Furthermore, uNGAL is a more sensitive and specific forecaster of renal flare in patients with a history of lupus nephritis than anti-dsDNA antibody titres.

The emerging role of biomarkers in diabetic and hypertensive chronic kidney disease

Currently used measures to assess kidney function and injury are largely inadequate. Markers such as serum creatinine, formulas to estimate glomerular filtration rate, cystatin C, and proteinuria largely identify an underlying disease process that is well established. Thus, there has been a recent effort to identify new biomarkers that reflect kidney function, early injury, and/or repair that ultimately can relate to progression or regression of damage. Several biomarkers emerged recently that are able to detect kidney damage earlier than is currently possible with traditional biomarkers such as serum creatinine and proteinuria. Identification of urine biomarkers has proven to be beneficial in recent years because of ease of handling, stability, and the ability to standardize the various markers to creatinine or other peptides generally already present in the urine. Recent markers such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and podocin have garnered a lot of attention. The emergence of these and other biomarkers is largely because of the evolution of novel genomic and proteomic applications in investigations of acute kidney injury and chronic kidney disease. In this article, we focus on the applications of these biomarkers in disease.

Plasma neutrophil gelatinase-associated lipocalin is an early biomarker for acute kidney injury in an adult ICU population

Purpose

Neutrophil gelatinase-associated lipocalin (NGAL) is a useful marker for acute kidney injury (AKI), particularly when the timing of renal insult is known. However, its performance in an adult critical care setting has not been well described. We performed this study to estimate the diagnostic accuracy of plasma NGAL for early detection of AKI and need for renal replacement therapy (RRT) in an adult intensive care unit (ICU).

Methods

We enrolled 307 consecutive adult patients admitted to a general medical-surgical ICU; 301 were included in the final analysis. Serial blood samples were analyzed for plasma NGAL using a standardized clinical platform. The primary outcome was AKI, defined as an increase in creatinine of at least 50% from baseline or a reduction in urine output to <0.5 ml/kg/h for >6 h.

Results

Of 301 patients, 133 (44%) had AKI during their ICU stay. Plasma NGAL was a good diagnostic marker for AKI development within the next 48 h (area under ROC 0.78, 95% CI 0.65–0.90), and for RRT use (area under ROC 0.82, 95% CI 0.70–0.95). Peak plasma NGAL concentrations increased with worsening AKI severity (R = 0.554, P < 0.001).

Conclusions

Plasma NGAL is a useful early marker for AKI in a heterogeneous adult ICU population, in which the timing of renal insult is largely unknown. It allows the diagnosis of AKI up to 48 h prior to a clinical diagnosis based on AKI consensus definitions. Additionally, it predicts need for RRT and correlates with AKI severity. Early identification of high risk patients may allow potentially beneficial therapies to be initiated early in the disease process before irreversible injury occurs.

Electronic supplementary material

The online version of this article (doi:10.1007/s00134-009-1711-1) contains supplementary material, which is available to authorized users.