Plasma neutrophil gelatinase-associated lipocalin for the prediction of acute kidney injury in acute heart failure.

Abstract

The accurate prediction of acute kidney injury (AKI) in patients with acute heart failure (AHF) is an unmet clinical need. Neutrophil gelatinase-associated lipocalin (NGAL) is a novel sensitive and specific marker of AKI.
A total of 207 consecutive patients presenting to the emergency department with AHF were enrolled. Plasma NGAL was measured in a blinded fashion at presentation and serially thereafter. The potential of plasma NGAL levels to predict AKI was assessed as the primary endpoint. We defined AKI according to the AKI Network classification.
Overall 60 patients (29%) experienced AKI. These patients were more likely to suffer from pre-existing chronic cardiac or kidney disease. At presentation, creatinine (median 140 (interquartile range (IQR), 91 to 203) umol/L versus 97 (76 to 132) umol/L, P<0.01) and NGAL (114.5 (IQR, 67.1 to 201.5) ng/ml versus 74.5 (60 to 113.9) ng/ml, P<0.01) levels were significantly higher in AKI compared to non-AKI patients. The prognostic accuracy for measurements obtained at presentation, as quantified by the area under the receiver operating characteristic curve was mediocre and comparable for the two markers (creatinine 0.69; 95%CI 0.59 to 0.79 versus NGAL 0.67; 95%CI 0.57 to 0.77). Serial measurements of NGAL did not further increase the prognostic accuracy for AKI. Creatinine, but not NGAL, remained an independent predictor of AKI (hazard ratio (HR) 1.12; 95%CI 1.00 to 1.25; P=0.04) in multivariable regression analysis.
Plasma NGAL levels do not adequately predict AKI in patients with AHF.

Full text

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RESEARCHOpen Access
Plasma neutrophil gelatinase-associated lipocalin
for the prediction of acute kidney injury in acute
heart failure
Tobias Breidthardt1,2,4*, Thenral Socrates1, Beatrice Drexler1, Markus Noveanu1,3, Corinna Heinisch1, Nisha Arenja1,
Theresia Klima1,2,5, Christina Züsli1, Tobias Reichlin1,3, Mihael Potocki1,3, Raphael Twerenbold1, Jürg Steiger2and
Christian Mueller1,3
Abstract
Introduction: The accurate prediction of acute kidney injury (AKI) in patients with acute heart failure (AHF) is an
unmet clinical need. Neutrophil gelatinase-associated lipocalin (NGAL) is a novel sensitive and specific marker of
AKI.
Methods: A total of 207 consecutive patients presenting to the emergency department with AHF were enrolled.
Plasma NGAL was measured in a blinded fashion at presentation and serially thereafter. The potential of plasma
NGAL levels to predict AKI was assessed as the primary endpoint. We defined AKI according to the AKI Network
classification.
Results: Overall 60 patients (29%) experienced AKI. These patients were more likely to suffer from pre-existing
chronic cardiac or kidney disease. At presentation, creatinine (median 140 (interquartile range (IQR), 91 to 203)
umol/L versus 97 (76 to 132) umol/L, P < 0.01) and NGAL (114.5 (IQR, 67.1 to 201.5) ng/ml versus 74.5 (60 to 113.9)
ng/ml, P < 0.01) levels were significantly higher in AKI compared to non-AKI patients. The prognostic accuracy for
measurements obtained at presentation, as quantified by the area under the receiver operating characteristic curve
was mediocre and comparable for the two markers (creatinine 0.69; 95%CI 0.59 to 0.79 versus NGAL 0.67; 95%CI
0.57 to 0.77). Serial measurements of NGAL did not further increase the prognostic accuracy for AKI. Creatinine, but
not NGAL, remained an independent predictor of AKI (hazard ratio (HR) 1.12; 95%CI 1.00 to 1.25; P = 0.04) in
multivariable regression analysis.
Conclusions: Plasma NGAL levels do not adequately predict AKI in patients with AHF.
Introduction
Acute kidney injury (AKI) is an increasingly common
complication in hospitalized patients. Over the last dec-
ade the incidence of AKI has steadily increased [1]. Cur-
rent estimates assume that annually about 17 million
hospital admissions in the United States are complicated
by AKI, resulting in additional health care costs of 10
billion dollars [2].
AKI occurring during acute heart failure (AHF) has
been termed the cardiorenal syndrome Type I [3]. AHF
patients developing AKI have been shown to have
increased morbidity, mortality and treatment costs [4,5].
Unfortunately, the accurate prediction of AKI is an
unmet clinical need [6].
Neutrophil gelatinase-associated lipocalin (NGAL; also
known as human neutrophil lipocalin, lipocalin-2, side-
rocalin, 24p3, or LCN2) is a small molecule that belongs
to the well-defined superfamily of proteins called lipoca-
lins [7]. Human NGAL was originally identified as a 25-
kDa protein associated with purified gelatinase obtained
from the supernatant of activated neutrophils, which
normally are the main cellular source of circulating
NGAL [7]. Subsequent studies have identified tubularly
secreted NGAL as a novel and specific biomarker for
* Correspondence: breidthardtt@uhbs.ch
1Department of Internal Medicine, University Hospital Basel, Peterplatz 1,
Basel, 4003, Switzerland
Full list of author information is available at the end of the article
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© 2012 Breidthardt et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.

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the early detection of AKI in several settings including
cardiac surgery [8,9], contrast agent administration
[10,11], unselected patients in the emergency depart-
ment [12] and in critically ill patients [13-15].
As the main pathophysiological mechanisms of AKI in
AHF as well as the timing of insults may differ from the
settings mentioned above, it is unknown whether these
promising initial findings can be extrapolated to AHF.
Therefore, we aimed to examine NGAL levels in the
prediction of AKI in patients with AHF.
Materials and methods
Setting and study population
This prospective study investigated the potential of
plasma NGAL levels to predict the occurrence of AKI
and worsening renal function (WRF) in consecutive
AHF patients presenting to the participating emergency
departments (University Hospital Basel, Kantonsspital
Aarau, and Kantonsspital Luzern) from April 2006 to
August 2009. To be eligible for enrollment, patients had
to be over 18 years old and present with symptoms and
signs of AHF. AHF was diagnosed and patients were
treated according to current European Society of Cardi-
ology (ESC) guidelines [16]. Patients undergoing chronic
hemodialysis were excluded. There were no other
excluding factors that may have omitted patients with
renal disease or biased their enrollment in the trial. AKI
and WRF diagnoses could not be determined in four
patients, who were treated in the emergency department
on an outpatient basis only and for whom only one
serum creatinine draw and no preadmission serum crea-
tinine values were available. These patients were
excluded from the analysis. The study was carried out
according to the principles of the Declaration of Hel-
sinki. It was approved by the local ethical committee
(Ethikkomission beider Basel, Reference-Number: EK
52/06). Written informed consent was obtained from all
participants.
Clinical evaluation and biomarker measurements
At the time of enrollment all patients underwent an
initial clinical assessment including clinical history, phy-
sical examination, pulse oximetry, blood tests including
B-type natriuretic peptide (BNP), and chest X-ray. Echo-
cardiography, blood gas analyses and cardiac magnetic
resonance imaging (MRI) were performed according to
the treating physicians’ recommendations. Creatinine
levels were measured at presentation to the emergency
department, daily for the next four days and at dis-
charge from the hospital. Blood samples for determina-
tion of NGAL were collected at presentation, in six-
hour intervals during the first 24 hours as well as after
36 hours and 48 hours. After centrifugation, samples
were frozen at -80°C until assayed in a blinded fashion
in a single batch using a fluorescence- immunoassay
(Triage®NGAL; Alere San Diego Incorporated; San
Diego, CA, USA). According to Alere the lower detec-
tion limit of the assay is 45 ng/ml, the upper detection
limit is 1,310 ng/ml. The product package insert
describes the lot to lot coefficient of variance as 6.4%,
5.8%, and 3.9% for low, medium, and high NGAL values,
respectively. The 95th percentile in 120 healthy indivi-
duals between 18 and 83 years old was 159 ng/ml. All
investigated cardiovascular drugs tested at concentra-
tions representing at least two times the maximal thera-
peutic dose, did not show crossreactivity or interference
with the assay.
Endpoints
The potential of plasma NGAL levels to predict the
occurrence of AKI during the first four days was
assessed as the primary endpoint. We defined and
graded AKI according to the Acute Kidney Injury Net-
work (AKIN) classification as a new-onset increase in
serum creatinine ≥ 0.3 mg/dl (26.4 mmol/l) over stable
baseline creatinine values [17]. AKI stage 1 included
acute creatinine increases between ≥ 0.3 mg/dl (≥ 26.4
μmol/l) and up to 200% over stable baseline creatinine,
while increases in serum creatinine between > 200% to
300% from stable baseline were considered stage 2. AKI
stage 3 entailed acute increases of serum creatinine to
more than 300% (> 3-fold) as well as serum creatinine
values ≥ 354 μmol/l showing an acute increase of at
least 0.5 mg/dl (44 μmol/l]) [17]. We determined base-
line kidney function for 189 (91%) patients by analysis
of serum creatinine and medical history using the elec-
tronic medical records for the six months prior the
index hospitalization. Baseline creatinine was defined as
the lowest creatinine value obtained by the individual
patient during the observational period. In the absence
of pre-admission data the lowest creatinine value mea-
sured during the index hospitalization was accepted as
the presumptive baseline value.
The prediction of in-hospital WRF was considered the
secondary endpoint. WRF was defined as an in-hospital
increase in serum creatinine exceeding or equal to 0.3
mg/dl (26.4 mmol/l) over the value at presentation, con-
sistent with several previous investigations [5,6]. The
patient flow through this study is depicted in Figure 1.
Statistical analysis
The statistical analyses were performed using the SPSS/
PC (version 19.0,
SPSS Inc., USA) and the R-project (online at http://
www.R-project.org) software packages. A statistical sig-
nificance level of 0.05 was used. Discrete variables are
expressed as counts (percentage) and continuous vari-
ables as means ± standard deviation (SD) or median and
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interquartile range [IQR], unless stated otherwise. The
comparison between the two groups was done with the
chi-square test and Fisher exact test for categorical vari-
ables and t-test for continuous variables if normally dis-
tributed or Mann-Whitney test if not normally
distributed. The variation between the two groups of
NGAL values was compared using the Kruskall-Wallis
test, Mann-Whitney test and two-way analysis of var-
iance (ANOVA) for repeated measurements. Compari-
sons between NGAL values at various time points for
Figure 1 Flow chart displaying the distribution of patients into AKI and WRF groups.
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individual patients were done using Wilcoxon test. The
Spearman rank correlation was used to perform correla-
tion analyses. All hypothesis testing was two-tailed.
The prognostic accuracy of the different models was
evaluated using receiver operating characteristic (ROC)
curve analysis. Areas under ROC curves were compared
using MedCalc software (version 9.2., MedCalc Software,
Mariakerke, Belgium). Univariate and multivariate binary
regression analysis was applied to identify predictors of
AKI and WRF. Overall 37 candidate variables were
assessed in univariate regression analysis. The variable
inclusion method was used for multivariate regression
analysis. Multivariate analysis included all significant
candidate variables (P < 0.05) established in univariate
analysis. To limit the effects of co-linearity between
multiple variables of renal impairment a simplified mul-
tivariate analysis was also conducted. The Hosmer-
Lemeshow test was conducted to compare the observed
and expected frequencies of AKI and WRF based on the
values of the estimated probabilities obtained by logistic
regression analysis.
Results
Baseline characteristics
Detailed baseline characteristics of the study population
are summarized in Table 1. The age of the 207 patients
ranged from 39 to 98 years and the incidence of cardio-
vascular co-morbidities was high. Overall 60 patients
experienced early AKI. These patients were more likely
to suffer from a chronic cardiac or kidney disease. Addi-
tionally, AKI patients were more often treated with out-
patient diuretics before being admitted to hospital and
received higher doses of loop diuretics during the first
three days than non-AKI patients (220 mg (85 to 328)
versus 140 mg (70 to 243], P = 0.01). However, the
more intense diuretic treatment was not associated with
a larger decline in body weight or natriuretic peptide
levels during the hospitalization (weight loss AKI: -3.0
kg ± 5.4 kg versus non-AKI: -4.3 kg ± 5.1 kg; P = 0.48;
BNP change AKI: -57% (-31% to -77%) versus -48%
(-8% to -70%), P = 0.38). The majority of AKI cases
occurred within the first 48 hours, with 19 (32%) cases
being present at presentation to the emergency depart-
ment, 11 (18%) cases occurring within the first 24 hours
and 20 (33%) cases being detected at day two (Figure 2).
The majority of AKI cases were graded as AKI stage 1
(n = 47; 78%). Only 7 (12%) patients reached AKI stage
2 and 6 (10%) patients developed AKI stage 3.
Plasma NGAL levels in patients experiencing acute kidney
injury
Plasma NGAL values at presentation of this heart failure
cohort were significantly correlated with age (r = 0.27, P
< 0.0001), admission hemoglobin levels (r = -0.23, P =
0.0002), admission creatinine values (r = 0.52, P <
0.0001) and baseline creatinine (r = 0.45, P < 0.0001),
but not to BNP levels (r = 0.11, P = 0.16), leukocyte
count (r = 0.15, P = 0.06), C-reactive protein values (r =
0.11, P = 0.135), body mass index (r = -0.12, P = 0.13)
or central venous pressure (r = -0.07, P = 0.49) mea-
sured by non-invasive compression sonography. Using
logarithmic values for non-normally distributed para-
meters did not change their correlations to NGAL levels
at presentation. Spot measurements of plasma NGAL
levels at presentation were significantly higher in
patients experiencing AKI within the first four days
compared to patients without AKI (114.5 ng/ml (67.1 to
201.5) versus 75.4 ng/ml (60.0 to 113.9), P = 0.001).
Furthermore, NGAL levels were significantly associated
with the severity of renal impairment (no AKI: 75.4 ng/
ml (60.0 to 113.9) versus AKI stage 1: 101.8 ng/ml [(1.0
to 193.8) versus AKI stage 2: 120.9 ng/ml (60.0 to
210.7) versus AKI stage 3: 231.5 ng/ml (174.8 to 479.3);
P < 0.001). This trend was mirrored by serum creatinine
values (P < 0.001). NGAL levels of patients presenting
with AKI were significantly higher than those of patients
developing AKI during the observational time period
and those not experiencing AKI at all (200.0 ng/ml
(115.6 to 240.7) versus 95.6 (60.0 to 133.8) versus 74.4
(60.0 to 112.7), P < 0.001) (Figure 3). A similar trend
could be observed for serum creatinine values.
Of note, in the 108 patients presenting with creatinine
levels within the normal range (< 110 mmol/l) no differ-
ences in NGAL levels could be observed between AKI
and non-AKI patients (median NGAL 60 ng/ml versus
65 ng/ml; P = 0.40).
Importantly, in an ANOVA 2-way analysis for
repeated measurements neither a change of NGAL
values over time (P = 0.66), nor a significant difference
between the NGAL levels of patients experiencing AKI
and those not experiencing AKI could be detected (P =
0.25).
Plasma NGAL as a predictor of acute kidney injury
To evaluate the potential of serum creatinine and spot
measurements of plasma NGAL at presentation to pre-
dict the occurrence of AKI, receiver operating charac-
teristic (ROC) analyses were performed. The area
under the ROC curve (AUC) for the prediction of
acute kidney injury was comparable for both markers
(creatinine 0.69; 95%CI 0.59 to 0.79 versus NGAL 0.67;
95%CI 0.57 to 0.77; creatinine/NGAL combined: 0.69;
95%CI 0.59 to 0.79) (Figure 4). Both models provided
adequate fit (P-values Hosmer-Lemeshow: creatinine =
0.89; NGAL = 0.48). The calculated NGAL cut-point
of 94 ng/ml that maximized the product of sensitivity
times specificity achieved a sensitivity of 0.65 and a
specificity of 0.65.
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In patients presenting with creatinine levels within the
normal range, the AUC for the prediction of AKI was
poor and comparable for both markers (creatinine: 0.51
versus NGAL 0.52). Furthermore, the potential of the
two markers to detect advanced AKI (stage 3) (AUC
creatinine: 0.94 versus AUC NGAL 0.88) was similar.
When entering these biomarkers into a univariate bin-
ary regression analysis increasing creatinine (HR 1.13;
95%CI 1.01 to 1.20; P < 0.001) and NGAL levels (HR
1.01; P < 0.001) significantly predicted the occurrence of
AKI (Table 2). During extensive multivariate regression
analysis (including all candidate variables identified dur-
ing univariate analysis) no marker was able to predict
AKI independently. In a simplified multivariate regres-
sion analysis aimed at reducing the effects of co-linearity
between multiple variables of renal impairment, admis-
sion serum creatinine remained the only independent
predictor of AKI (HR 1.12; 95%CI 1.00 to 1.25; P =
0.04) (Table 2). Spot measurements of NGAL failed to
predict the occurrence of early AKI.
Table 1 Baseline Characteristics of 207 patients
All patientsNo AKIAKI
P-values
Total number of patients
Age (year)
Female
Medical History
Arterial Hypertension
Heart Failure
Coronary artery disease
Diabetes mellitus
Chronic kidney disease
Neoplastic disease
Long term medication use
Diuretics
Betablockers
Nitrates
Renin Angiotensin System-Blockers
Aspirin
Anticoagulation
Vital status
Blood pressure (mmHg)
Systolic
Diastolic
Heart rate (per minute)
Respiratory rate (per minute)
Oxygen saturation (%)
Body Mass Index (kg/m2)
Noninvasive CVP (cmH20)
Laboratory values
LV ejection fraction (%)
Leucocytes (x109/L)
Hemoglobin (g/l)
C-reactive protein (mg/l)
Urea (mmol/l)
Uric acid (mmol/l)
Creatinine (mmol/l)
Baseline eGFR (ml/min)*
NGAL (ng/ml)
BNP (pg/ml)
Troponin T (ug/l)
207
80 [74-85]
85 (41)
147 (71)
80 [73-84]
59 (40)
60 (29)
80 [76-86]
26 (43)
0.19
0.53
152 (73)
103 (50)
100 (48)
69 (33)
92 (44)
27 (13)
106 (72)
67 (46)
66 (45)
49 (33)
57 (39)
20 (14)
46 (76)
36 (60)
34 (57)
20 (33)
35 (58)
7 (12)
0.27
0.03
0.09
0.87
< 0.01
0.27
153 (74)
123 (59)
44 (21)
129 (62)
85 (41)
77 (37)
105 (71)
83 (54)
30 (20)
88 (61)
60 (41)
50 (34)
48 (80)
40 (66)
14 (23)
41 (68)
25 (42)
27 (45)
0.06
0.11
0.57
0.34
0.75
0.11
136 [115-152]
84 [69-96]
85 [73-102]
20 [18-27]
97 [95-98]
26 [23-30]
13 [9-18]
138 [117-157]
84 [74-97]
86 [74-100]
20 [16-28]
96 [95-98]
26 [23-30]
13 [8-20]
130 [112-144]
75 [67-92]
85 [75-107]
22 [18-26]
97 [93-98]
26 [24-30]
13 [8-17]
0.05
0.09
0.63
0.63
0.91
0.58
0.59
40 [25-55]
8.1 [6.5-10.6]
123 [114-139]
11.6 [4.2-32.3]
9.2 [7.1-13.2]
461 [370-582]
100 [78-143]
52 [35-74]
79.6 [60.0-133.6]
1377 [847-2428]
0.02 [0.01-0.04]
45 [25-55]
8.1[6.7-10.0]
127 [120-139]
9.4 [4.1-32.9]
8.9 [6.9-12.8]
448 [347-576]
97 [76-132]
57 [38-75]
75.4 [60.0-113.9]
1321 [792-2491]
0.01 [0.01- 0.30]
40 [29-50]
8.2 [6.9-12.0]
122 [107-139]
20.4 [8.1-40.3]
11.8 [8.5-18.1]
505 [407-624]
140 [91-203]
42 [27-63]
114.5 [67.1-201.5]
1470 [731-2444]
0.03 [0.01-0.60]
0.87
0.23
0.25
0.03
< 0.01
0.02
< 0.01
< 0.01
< 0.01
0.49
< 0.01
Data are presented as median [interquartile range], number of patients (%)as appropriate; Abbreviations:eGFR denotes estimated glomerular filtration rate, NGAL
denotes Neutrophil gelatinase-associated lipocalin; BNP denotes B-type natriuretic peptide, CVP denotes central venous pressure
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During serial sampling no significant changes in
plasma NGAL levels were observed in the 41 patients
experiencing AKI after presentation. Hence, NGAL
changes over the first 24 hours did not provide addi-
tional predictive information.
Plasma NGAL as a predictor of in-hospital worsening
renal function
Overall, 50 (24%) patients experienced in-hospital WRF
during the first four days. Reflecting the occurrence of
WRF post presentation, admission creatinine (124
mmol/l (82 to 168) versus 110 mmol/l (82-150), p =
0.80) and plasma NGAL (94.0 ng/ml (60.0-182.4) versus
83.7 (0.0 to 135.3), P = 0.34) levels were similar in WRF
and non-WRF patients. Again, no significant change
over time (P = 0.46) or inter-group differences (P =
0.43) were found during repeated measurements. In
ROC curve analysis the AUC was comparable for both
markers (creatinine: 0.56; 95%CI 0.45 to 0.67 versus
NGAL: 0.52; 95%CI 0.41 to 0.63) (Figure 5). In a uni-
variate regression analysis model NGAL values (HR
1.00; 95%CI 0.99 to 1.00; P = 0.09) failed to predict
WRF independently.
Discussion
In this investigation we examined the potential of
plasma NGAL levels at admission and serially thereafter
to predict the occurrence of AKI and WRF in 207
patients with AHF. There are several key findings in this
study. First, in AHF patients, plasma NGAL levels are
significantly correlated to renal indices at presentation
but also to age and baseline renal function. However,
plasma NGAL levels are not associated with the extent
of hemodynamic cardiac stress as quantified by BNP,
the extent of venous congestion or inflammation. Sec-
ond and most importantly, we found that spot measure-
ments of plasma NGAL at presentation failed to
improve the prediction of AKI over creatinine measure-
ment. While both markers were significantly higher in
patients experiencing AKI, their accuracy for the predic-
tion of AKI was only modest. Third, the combination of
plasma NGAL levels and creatinine did not result in a
higher accuracy than creatinine alone. Fourth, the accu-
racy of plasma NGAL was even lower in patients pre-
senting with creatinine values within the normal range.
Fifth, plasma NGAL levels did not show a clear trend
preceding the occurrence of AKI. Consequently, serial
measurements did not add to the diagnostic potential of
plasma NGAL at presentation.
Our results represent the first larger scale study inves-
tigating the potential of plasma NGAL in the setting of
AHF. The results of an earlier study enrolling 91
patients with AHF support our observations. Aghel and
colleagues also found spot measurements of serum
NGAL to be significantly higher in patients experiencing
early AKI [18]. Furthermore, their study described
Figure 2 Bar chart displaying the time of first diagnosis of AKI based on serial creatinine measurements.
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comparable AUCs for serum NGAL and estimated glo-
merular filtration rate (eGFR) for the prediction of early
AKI (0.7 and 0.61, respectively). Unfortunately, due to
the small number of patients in their study no extensive
multivariate analysis could be performed. Contrastingly,
a very recent study by Alvelos and co-workers found
spot measurements of NGAL to powerfully predict AKI
in 114 hospitalized AHF patients (AUC 0.93)[19]. How-
ever, their study differs significantly from the present
study and also the work presented by Aghel, since it
selectively assessed the predictive potential of NGAL
levels drawn on the first in-hospital day and only con-
sidered AKI occurring between day two and day three.
Applying these criteria to our population led to the
exclusion of 24 (40%) early AKI cases, explaining the
lower incidence of AKI occurring in the Alvelos study
(12% versus 29%). Additionally, using the Alvelos defini-
tion of early AKI in a secondary analysis, we found the
predictive accuracy of NGAL levels at presentation to be
comparable to our primary analysis (AUC 0.61) and
were therefore not able to confirm their findings. It can
only be speculated that the narrower and sub-acute
observational period in the Alvelos study reflects a more
specific, NGAL-detectable AKI pathology, while the
more inclusive observational period in this study might
cover a wider range of AKI triggers.
Figure 3 Box Plots showing plasma NGAL levels at presentation to the emergency department in AKI and non-AKI patients.
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The results obtained for AHF patients differ from the
results obtained in other clinical settings, such as after
cardiac surgery [8,9] and contrast agent administration
[10,11], in which NGAL was established as a promising
early marker of AKI. However, contrast-induced
nephropathy and post-surgical AKI are marked by a
clear time of injury. In these settings NGAL has repeat-
edly been proven to increase significantly three to four
hours after the insult, while creatinine only increases 48
to 72 hours later. In contrast, the pathophysiological
mechanisms underlying renal dysfunction in patients
with AHF appear to be multifactorial and not well
defined. Overall, an imbalance between the failing heart,
the neurohumoral system and inflammatory responses
has been associated with the occurrence of renal dys-
function [20]. Additionally, hemodynamic factors includ-
ing the adequacy of renal perfusion [21] and the degree
of venous congestion [22,23] as well as drug nephrotoxi-
city appear to contribute to the development of AKI in
AHF. Hence, AKI in AHF might well be caused by serial
insults making its prediction especially difficult. Simi-
larly, two studies directly comparing the predictive
potential of admission NGAL to admission creatinine
[13] or clinical prediction models [15] in critically ill
patients, found classical predictors of AKI to at least
equal if not surpass the potential of NGAL. Hence, even
in the setting of critically ill patients, NGAL levels
might not be able to act as a stand-alone test [24,25].
The significant correlation of admission NGAL levels
with baseline creatinine levels observed in this study
and the correlation of urinary NGAL levels with renal
indices in stable chronic heart failure [26,27] suggest
that NGAL levels in AHF may reflect chronic structural
tubular damage. This thesis is further supported by the
stable NGAL levels over time in patients experiencing
AKI in this study. A chronic structural tubular damage
and persistently elevated NGAL levels appear to be
widespread in the setting of heart failure [26] and ele-
vated NGAL levels have been associated with increased
short-term mortality [28,29]. Consequently, the dam-
pened kinetics of NGAL levels before the occurrence of
AKI might contribute to the limited predictive potential
of plasma NGAL in AHF.
Additionally, recent studies found circulating NGAL
levels to be influenced by various extra-renal factors
[30]. Systemically elevated NGAL levels have been
Figure 4 Receiver operating characteristic curves displaying the inability of admission creatinine, and plasma NGAL to predict the
occurrence of AKI.
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observed in infectious diseases [7], primary and second-
ary anemia [31], various human cancers [30] and animal
models of obesity [32]. In the setting of cardiovascular
diseases, elevated NGAL levels were found in coronary
plaques, the failing myocardium and in the circulation
of heart failure patients [33]. The combined influence of
this systemic NGAL pool might contribute to the lim-
ited predictive potential of plasma NGAL in AHF. The
predictive potential of urinary NGAL, which appears to
be less impacted by extra-renal factors, has not been
selectively examined in AHF patients yet. However, a
recent meta-analysis including patients from 19 studies
showed comparable performances for plasma and urin-
ary NGAL [34].
Potential limitations of the current study merit consid-
eration. First, only Swiss centers participated in this
study. However as baseline characteristics, treatment
and the frequency of AKI rates were similar to those
observed in large registry studies, we consider our
results representative. Second, we did not include the
urine output criteria of the AKIN classification into the
definition and grading of AKI, as loop diuretics impact-
ing urine were used in the majority of our patients and
adequate urine output collection is especially difficult
during the early in-hospital period marked by repeated
changes of the care-team. However, these difficulties are
shared by previously published studies assessing the pre-
dictive potential of NGAL in the non-ICU setting,
which also opted to exclude the urine output criteria for
AKI diagnosis [12,18,19]. Third, we cannot differentiate
between ‘pre-renal’ and ‘structural” disturbances of kid-
ney function as the reason for AKI. However, indepen-
dent of the underlying pathology, minor changes of
renal function have repeatedly been associated with a
Table 2 Prediction of the occurrence of acute kidney injury in univariate and multivariate regression analysis
Univariate analysis
Predictor Hazard Ratio
P-value
Age (yrs)
Hx Heart Failure
Hx Chronic Kidney Disease
Steady State Creatinine > 110 μol/l
Outpatient Diuretic Treatment
Systolic Blood Pressure (mmHg)
Loop Diuretic Dose during first 72h
Urea (mmo/l)
Uric Acid (mmol/l)
C-reactive protein (mg/l)
Troponin T (ug/l)
B-type natriuretic peptide (pg/ml)
(for every increase of 100 pg/ml)
LV ejection fraction (%)
Creatinine (mmol/l)
(for every increase of 10 mml/l)
NGAL ng/ml
(for every increase of 10 ng/ml)
NGAL > 94 ng/ml
NGAL > 140 ng/ml
Multivariate analysis
Hx Heart Failure
Steady State Creatinine > 110 μmol/l
Systolic Blood Pressure (mmHg)
Outpatient Diuretic Treatment
Loop Diuretic Dose during first 72h
C-reactive protein (mg/l)
Troponin T (ug/l)
Creatinine (mmol/l)
(for every increase of 10 mml/l)
NGAL (ng/ml)
(for every increase of 10 ng/ml)
HR 1.03 (95%CI 0.99-1.06)
HR 2.02 (95%CI 1.08-3.81)
HR 2.15 (95%CI 1.16-3.99)
HR 2.21 (95%CI 1.16-4.23)
HR 2.36 (95%CI 1.03-5.41)
HR 0.99 (95%CI 0.97-0.99)
HR 1.00 (95%CI 1.00-1.01)
HR 1.09 (95%CI 1.04-1.15)
HR 1.00 (95%Ci 1.00-1.00)
HR 1.01 (95%CI 1.00-1.01)
HR 1.06 (95%CI 1.01-1.19)
HR1.00 (95%CI 0.99-1.02)
0.06
0.03
0.02
0.02
0.04
0.03
< 0.01
< 0.001
0.02
0.03
0.02
0.80
HR 0.99 (95%CI 0.97-1.02)
HR 1.13 (95%CI 1.01-1.20)
0.53
< 0.001
HR 1.01 (95%CI 1.04-1.15) < 0.001
HR 1.44 (96%CI 0.15-14.20)
HR 3.40 (95%CI 1.61-7.15)
0.76
0.001
HR 1.75 (95%CI 0.64-4.80)
HR 2.41 (95%CI 0.66-8.88)
HR 1.01 (95%CI 0.99-1.02)
HR 1.25 (95%CI 0.32-4.02)
HR 1.00 (95%CI 0.99-1.00)
HR 1.00 (95%CI 0.99-1.01)
HR 3.72 (95%CI 0.02-13.53)
HR 1.12 (95%CI 1.00-1.24)
0.24
0.41
0.43
0.58
0.86
0.95
0.63
0.04
HR 1.05 (95%CI 0.98-1.13) 0.18
To limit the effects of co-linearity between multiple parameters of renal and cardiac function multivariate analysis contained only the strongest univariate
predictor in each class (acute renal function, chronic renal impairment, acute cardiac injury, chronic heart failure).
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worse patient outcome [35,36]. We therefore believe
that adequate prediction of AKI in AHF should be able
to foresee these prognostically important creatinine
changes. Fourth, the definition of AKI is based on serial
measurements of serum creatinine, hence an incorpora-
tion bias [37,38] might have favored presentation values
of serum creatinine in predicting AKI in ROC curve and
regression analyses. However, in the absence of a non-
creatinine based definition of AKI, we feel that to pro-
vide tangible clinical benefit plasma NGAL would have
to improve the early detection of AKI over the current
gold standard. Finally, clinical parameters (most impor-
tantly chronic kidney disease) previously shown to pre-
dict in-hospital AKI (observational period presentation
to discharge) [6,39,40] failed to independently predict
early AKI in this study. These differences most likely
represent the increased importance of acute parameters
(serum creatinine incorporating community acquired
AKI and chronic kidney disease) versus chronic para-
meters (chronic kidney disease, outpatient diuretic ther-
apy) in the prediction of early versus late AKI.
Nevertheless, these clinical parameters remained non-
significantly associated with an increased occurrence of
early AKI.
Conclusion
Plasma NGAL levels do not adequately predict AKI and
WRF in patients with AHF. This lack of predictive
power is probably caused by the multifactorial pathome-
chanism underlying the cardiorenal syndrome and
chronically elevated NGAL levels caused by chronic tub-
ular injury and extrarenal NGAL production in heart
failure patients.
Key messages
• Spot measurements of plasma NGAL at presenta-
tion do not improve the prediction of AKI over crea-
tinine in patients with acute heart failure.
• The combination of plasma NGAL levels and crea-
tinine does not result in a higher predictive accuracy
than creatinine alone.
• In acute heart failure plasma NGAL levels do not
show a clear trend preceding the occurrence of AKI.
Figure 5 Receiver operating characteristic curves displaying the inability of admission creatinine, and plasma NGAL to predict the
occurrence of WRF.
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• Consequently, serial measurements do not add to
the predictive potential of plasma NGAL at
presentation.
Abbreviations
AHF: acute heart failure; AKI: acute kidney injury; AKIN: Acute Kidney Injury
Network; AUC: area under the curve; ANOVA: analysis of variance; BNP: B-
type natriuretic peptide; eGFR: estimated glomerular filtration rate; IQR:
interquartile range; MRI: magnetic resonance imaging; NGAL: neutrophil
gelatinase-associated lipocalin; ROC: receiver operating characteristic; WRF:
worsening renal function
Acknowledgements
We are indebted to the patients who participated in the study and to the
Emergency Department staff as well as the laboratory technicians for their
most valuable efforts. Furthermore, the authors thank Dr. Etienne Gayat,
Hôpital Lariboisière APHP; University Paris for his statistical support. This
study was supported by research grants from the University of Basel (to Dr.
Breidthardt), the Swiss National Science Foundation (to Dr. Mueller), and
ALERE. The funding bodies had no role in study design, data collection and
analysis, decision to publish, or preparation of the manuscript.
Author details
1Department of Internal Medicine, University Hospital Basel, Peterplatz 1,
Basel, 4003, Switzerland.2Department of Nephrology and Transplant
Immunology, University Hospital Basel, Peterplatz 1, Basel, 4003, Switzerland.
3Department of Cardiology, University Hospital Basel, Peterplatz 1, Basel,
4003, Switzerland.4Department of Renal Medicine, Royal Derby Hospital,
Uttoxeter Road, Derby, DE22 3NE, UK.5Department of Nephrology,
Kantonsspital, CH-5001 Aarau, Switzerland.
Authors’ contributions
TB and CM participated in the study concept and design, acquisition of
data, analysis and interpretation of data, drafting of the manuscript, critical
revision of the manuscript for important intellectual content and had full
access to all of the data in the study and take responsibility for the integrity
of the data and the accuracy of the data analysis. TS, BD, MN, TK, NA, CZ,
CH, TR, MP, and RT participated in acquisition of data, analysis and
interpretation of data and critical revision of the manuscript for important
intellectual content. JS participated in analysis, interpretation of data, drafting
of the manuscript and critical revision of the manuscript for important
intellectual content. All authors read and approved the final manuscript.
Competing interests
CM has received research support from Abbott, Alere, Biosite, Brahms,
Roche, Siemens and Behring. The NGAL measurements were provided free
of charge by Alere. The other co-authors have no competing interests.
Received: 20 June 2011 Revised: 17 October 2011
Accepted: 7 January 2012 Published: 7 January 2012
References
1. Hsu CY, McCulloch CE, Fan D, Ordonez JD, Chertow GM, Go AS:
Community-based incidence of acute renal failure. Kidney Int 2007,
72:208-212.
2. Chertow GM, Burdick E, Honour M, Bonventre JV, Bates DW: Acute kidney
injury, mortality, length of stay, and costs in hospitalized patients. J Am
Soc Nephrol 2005, 16:3365-3370.
3.Ronco C, McCullough P, Anker SD, Anand I, Aspromonte N, Bagshaw SM,
Bellomo R, Berl T, Bobek I, Cruz DN, Daliento L, Davenport A, Haapio M,
Hillege H, House AA, Katz N, Maisel A, Mankad S, Zanco P, Mebazaa A,
Palazzuoli A, Ronco F, Shaw A, Sheinfeld G, Soni S, Vescovo G,
Zamperetti N, Ponikowski P, Acute Dialysis Quality Initiative (ADQI)
consensus group: Cardio-renal syndromes: report from the consensus
conference of the acute dialysis quality initiative. Eur Heart J 2010,
31:703-711.
4. Hata N, Yokoyama S, Shinada T, Kobayashi N, Shirakabe A, Tomita K,
Kitamura M, Kurihara O, Takahashi Y: Acute kidney injury and outcomes in
acute decompensated heart failure: evaluation of the RIFLE criteria in an
acutely ill heart failure population. Eur J Heart Fail 2010, 12:32-37.
Damman K, Navis G, Voors AA, Asselbergs FW, Smilde TD, Cleland JG, van
Veldhuisen DJ, Hillege HL: Worsening renal function and prognosis in
heart failure: systematic review and meta-analysis. J Card Fail 2007,
13:599-608.
Breidthardt T, Socrates T, Noveanu M, Klima T, Heinisch C, Reichlin T,
Potocki M, Nowak A, Tschung C, Arenja N, Bingisser R, Mueller C: Effect and
Clinical Prediction of Worsening Renal Function in Acute
Decompensated Heart Failure. Am J Cardiol 2011, 107:730-735.
Bolignano D, Donato V, Coppolino G, Campo S, Buemi A, Lacquaniti A,
Buemi M: Neutrophil gelatinase-associated lipocalin (NGAL) as a marker
of kidney damage. Am J Kidney Dis 2008, 52:595-605.
Wagener G, Jan M, Kim M, Mori K, Barasch JM, Sladen RN, Lee HT:
Association between increases in urinary neutrophil gelatinase-
associated lipocalin and acute renal dysfunction after adult cardiac
surgery. Anesthesiology 2006, 105:485-491.
Mishra J, Dent C, Tarabishi R, Mitsnefes MM, Ma Q, Kelly C, Ruff SM,
Zahedi K, Shao M, Bean J, Mori K, Barasch J, Devarajan P: Neutrophil
gelatinase-associated lipocalin (NGAL) as a biomarker for acute renal
injury after cardiac surgery. Lancet 2005, 365:1231-1238.
Bachorzewska-Gajewska H, Malyszko J, Sitniewska E, Malyszko JS,
Dobrzycki S: Neutrophil-gelatinase-associated lipocalin and renal function
after percutaneous coronary interventions. Am J Nephrol 2006,
26:287-292.
Hirsch R, Dent C, Pfriem H, Allen J, Beekman RH, Ma Q, Dastrala S,
Bennett M, Mitsnefes M, Devarajan P: NGAL is an early predictive
biomarker of contrast-induced nephropathy in children. Pediatr Nephrol
2007, 22:2089-2095.
Nickolas TL, O’Rourke MJ, Yang J, Sise ME, Canetta PA, Barasch N, Buchen C,
Khan F, Mori K, Giglio J, Devarajan P, Barasch J: Sensitivity and specificity
of a single emergency department measurement of urinary neutrophil
gelatinase-associated lipocalin for diagnosing acute kidney injury. Ann
Intern Med 2008, 148:810-819.
de Geus HR, Bakker J, Lesaffre EM, le Noble JL: Neutrophil gelatinase-
associated lipocalin at ICU admission predicts for acute kidney injury in
adult patients. Am J Respir Crit Care Med 2011, 183:907-914.
Wheeler DS, Devarajan P, Ma Q, Harmon K, Monaco M, Cvijanovich N,
Wong HR: Serum neutrophil gelatinase-associated lipocalin (NGAL) as a
marker of acute kidney injury in critically ill children with septic shock.
Crit Care Med 2008, 36:1297-1303.
Siew ED, Ware LB, Gebretsadik T, Shintani A, Moons KG, Wickersham N,
Bossert F, Ikizler TA: Urine neutrophil gelatinase-associated lipocalin
moderately predicts acute kidney injury in critically ill adults. J Am Soc
Nephrol 2009, 20:1823-1832.
Dickstein K: ESC guidelines for the diagnosis and treatment of acute and
chronic heart failure 2008: application of natriuretic peptides. Reply. Eur
Heart J 2008 2009, 30:383.
Mehta RL, Kellum JA, Shah SV, Molitoris BA, Ronco C, Warnock DG, Levin A:
Acute Kidney Injury Network: report of an initiative to improve
outcomes in acute kidney injury. Crit Care 2007, 11:R31.
Aghel A, Shrestha K, Mullens W, Borowski A, Tang WH: Serum neutrophil
gelatinase-associated lipocalin (NGAL) in predicting worsening renal
function in acute decompensated heart failure. J Card Fail 2010, 16:49-54.
Alvelos M, Pimentel R, Pinho E, Gomes A, Lourenco P, Teles MJ, Almeida P,
Guimaraes JT, Bettencourt P: Neutrophil gelatinase-associated lipocalin in
the diagnosis of type 1 cardio-renal syndrome in the general ward. Clin
J Am Soc Nephrol 2011, 6:476-481.
Tang WH, Mullens W: Cardiorenal syndrome in decompensated heart
failure. Heart 2010, 96:255-260.
Ljungman S, Laragh JH, Cody RJ: Role of the kidney in congestive heart
failure. Relationship of cardiac index to kidney function. Drugs 1990,
39(Suppl 4):10-21, discussion 22-14.
Damman K, van Deursen VM, Navis G, Voors AA, van Veldhuisen DJ,
Hillege HL: Increased central venous pressure is associated with impaired
renal function and mortality in a broad spectrum of patients with
cardiovascular disease. J Am Coll Cardiol 2009, 53:582-588.
Uthoff H, Breidthardt T, Klima T, Aschwanden M, Arenja N, Socrates T,
Heinisch C, Noveanu M, Frischknecht B, Baumann U, Jaeger KA, Mueller C:
Central venous pressure and impaired renal function in patients with
acute heart failure. Eur J Heart Fail 2011, 13:432-439.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
Breidthardt et al. Critical Care 2012, 16:R2
http://ccforum.com/content/16/1/R2
Page 11 of 12

Page 12

24.Endre ZH, Pickering JW, Walker RJ, Devarajan P, Edelstein CL, Bonventre JV,
Frampton CM, Bennett MR, Ma Q, Sabbisetti VS, Vaidya VS, Walcher AM,
Shaw GM, Henderson SJ, Nejat M, Schollum JB, George PM: Improved
performance of urinary biomarkers of acute kidney injury in the critically
ill by stratification for injury duration and baseline renal function. Kidney
Int 2011, 79:1119-1130.
Lameire NH, Vanholder RC, Van Biesen WA: How to use biomarkers
efficiently in acute kidney injury. Kidney Int 2011, 79:1047-1050.
Damman K, van Veldhuisen DJ, Navis G, Voors AA, Hillege HL: Urinary
neutrophil gelatinase associated lipocalin (NGAL), a marker of tubular
damage, is increased in patients with chronic heart failure. Eur J Heart
Fail 2008, 10:997-1000.
Poniatowski B, Malyszko J, Bachorzewska-Gajewska H, Malyszko JS,
Dobrzycki S: Serum neutrophil gelatinase-associated lipocalin as a marker
of renal function in patients with chronic heart failure and coronary
artery disease. Kidney Blood Press Res 2009, 32:77-80.
Maisel AS, Mueller C, Fitzgerald R, Brikhan R, Hiestand BC, Iqbal N,
Clopton P, van Veldhuisen DJ: Prognostic utility of plasma neutrophil
gelatinase-associated lipocalin in patients with acute heart failure: the
NGAL EvaLuation Along with B-type NaTriuretic Peptide in acutely
decompensated heart failure (GALLANT) trial. Eur J Heart Fail 2011,
13:846-851.
Alvelos M, Lourenco P, Dias C, Amorim M, Rema J, Leite AB, Guimaraes JT,
Almeida P, Bettencourt P: Prognostic value of neutrophil gelatinase-
associated lipocalin in acute heart failure. Int J Cardiol .
Devarajan P: Review: neutrophil gelatinase-associated lipocalin: a
troponin-like biomarker for human acute kidney injury. Nephrology
(Carlton) 2010, 15:419-428.
Bolignano D, Coppolino G, Donato V, Lacquaniti A, Bono C, Buemi M:
Neutrophil gelatinase-associated lipocalin (NGAL): a new piece of the
anemia puzzle? Med Sci Monit 2010, 16:RA131-135.
Yan QW, Yang Q, Mody N, Graham TE, Hsu CH, Xu Z, Houstis NE, Kahn BB,
Rosen ED: The adipokine lipocalin 2 is regulated by obesity and
promotes insulin resistance. Diabetes 2007, 56:2533-2540.
Yndestad A, Landrø L, Ueland T, Dahl CP, Flo TH, Vinge LE, Espevik T,
Frøland SS, Husberg C, Christensen G, Dickstein K, Kjekshus J, Øie E,
Gullestad L, Aukrust P: Increased systemic and myocardial expression of
neutrophil gelatinase-associated lipocalin in clinical and experimental
heart failure. Eur Heart J 2009, 30:1229-1236.
Haase M, Bellomo R, Devarajan P, Schlattmann P, Haase-Fielitz A: Accuracy
of neutrophil gelatinase-associated lipocalin (NGAL) in diagnosis and
prognosis in acute kidney injury: a systematic review and meta-analysis.
Am J Kidney Dis 2009, 54:1012-1024.
Coca SG, Peixoto AJ, Garg AX, Krumholz HM, Parikh CR: The prognostic
importance of a small acute decrement in kidney function in
hospitalized patients: a systematic review and meta-analysis. Am J Kidney
Dis 2007, 50:712-720.
Gottlieb SS, Abraham W, Butler J, Forman DE, Loh E, Massie BM,
O’Connor CM, Rich MW, Stevenson LW, Young J, Krumholz HM: The
prognostic importance of different definitions of worsening renal
function in congestive heart failure. J Card Fail 2002, 8:136-141.
Worster A, Carpenter C: Incorporation bias in studies of diagnostic tests:
how to avoid being biased about bias. CJEM 2008, 10:174-175.
Whiting P, Rutjes AW, Reitsma JB, Glas AS, Bossuyt PM, Kleijnen J: Sources
of variation and bias in studies of diagnostic accuracy: a systematic
review. Ann Intern Med 2004, 140:189-202.
Forman DE, Butler J, Wang Y, Abraham WT, O’Connor CM, Gottlieb SS,
Loh E, Massie BM, Rich MW, Stevenson LW, Young JB, Krumholz HM:
Incidence, predictors at admission, and impact of worsening renal
function among patients hospitalized with heart failure. J Am Coll Cardiol
2004, 43:61-67.
Cowie MR, Komajda M, Murray-Thomas T, Underwood J, Ticho B:
Prevalence and impact of worsening renal function in patients
hospitalized with decompensated heart failure: results of the
prospective outcomes study in heart failure (POSH). Eur Heart J 2006,
27:1216-1222.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
doi:10.1186/cc10600
Cite this article as: Breidthardt et al.: Plasma neutrophil gelatinase-
associated lipocalin for the prediction of acute kidney injury in acute
heart failure. Critical Care 2012 16:R2.
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