Objectives: To evaluate urine neutrophil gelatinase-associated lipocalin (uNGAL) concentration and its relation with causes, categories, stages and biochemical indexes of acute kidney injury (AKI) patients.
Trang 1STUDY ON THE CONCENTRATION OF URINE NEUTROPHIL GELATINASE-ASSOCIATED LIPOCALIN IN ACUTE RENAL
FAILURE PATIENTS
Pham Ngoc Huy Tuan*; Le Viet Thang**
SUMMARY
Objectives: To evaluate urine neutrophil gelatinase-associated lipocalin (uNGAL) concentration and its relation with causes, categories, stages and biochemical indexes of acute kidney injury (AKI) patients Subjects and methods: A prospective, cross-sectional study in 96 patients with AKI who admitted to General ICU, Trungvuong Hospital, Hochiminh city from 12 - 2013 to
01 - 2017 and a control group of 51 healthy people uNGAL had been done in all 96 patients and healthy people Results: All of the AKI patients (100%) had uNGAL elevation The average concentration of uNGAL in study group (412.26 ng/mL) was significantly higher than in control group (10.74 ng/mL) with p < 0.001 There was no relationship between AKI causes and uNGAL concentration with p > 0.05 The concentration of uNGAL was significantly higher in oliguria group in comparison with non-oliguria group (558.32 ng/mL vs 342.6 ng/mL) with p < 0.005 Patients’ uNGAL concentrations at the time of ICU admission were significantly related to their KDIGO stage (p < 0.001) Urinary NGAL had a moderate positive relationship with serum urea concentration (r = 0.529, p < 0.001) and a strong positive linear relationship with serum creatinine concentration (r = 0.852, p < 0.001) Conclusion: Urinary NGAL elevation was common in AKI patients The concentration of uNGAL depended on category and stage of AKI It had a moderate positive relationship with serum urea and strong positive relationship with creatinine concentration
* Keywords: Acute kidney injury; Urine neutrophil gelatinase-associated lipocalin
INTRODUCTION
Acute kidney injury is a common and
devastating problem with in-hospital mortality
of 40% to 80% in the intensive care setting
[10] The traditional blood (creatinine,
blood urea nitrogen) and urine markers of
kidney injury (casts, fractional excretion of
sodium, urinary concentrating ability) that
have been used for decades in clinical
studies for diagnosis and prognosis of AKI
are insensitive and nonspecific and do not
directly reflect injury to kidney cells Therefore, early recognition of renal injury
is important and may help prevent further renal damage and functional impairment Neutrophil gelatinase-associated lipocalin
is a small, 23 kDa protein that is an early biomarker for ischemic, septic or nephrotoxic kidney injury It is normally produced at low levels by the epithelial cells of the kidney, but it is quickly upregulated in the thick ascending limb (TAL) of the loop of Henle and the collecting ducts within three
* Trungvuong Hospital
** 103 Military Hospital
Corresponding author: Pham Ngoc Huy Tuan (bshuytuantv@yahoo.com.vn)
Date received: 12/09/2017
Date accepted: 22/11/2017
Trang 2hours of tubular epithelial injury Urinary
NGAL (uNGAL) has been evaluated as an
early biomarker of renal tubular damage
in a acute clinical settings such as the
operating room, ICU and emergency
department, and in high-risk procedures
such as cardiac surgery, radio-contrast
injection and after adult and pediatric
kidney and liver transplantation[1, 6, 7, 8, 9]
There is considerable evidence that
compared to increases in serum creatinine,
NGAL detects early or subclinical kidney
injury earlier, and predicts dialysis
requirement and mortality better[1]
In Vietnam, there are lack of studies on
the role of uNGAL in AKI diagnosis and
prognogsis in patients admitted to General
ICU Therefore, we have conducted this
research with the aim: Evaluation of the
uNGAL concentration and its relation with
causes, categories, stages and some
biochemical indexes of AKI patients
SUBJECTS AND METHODS
1 Subject
The study was conducted with a study
group of 96 AKI patients who admitted
to General ICU, Trung Vuong Hospital,
Hochiminh city from 12 - 2013 to 01 - 2017
and a control group of 51 healthy people
* Excluding criteria: Patients with chronic
kidney failure, did not fit with diagnostic
criteria, did not enough test results, anuria
patients or did not agree to participate in
the study
2 Methods
* Study design: A cross-sectional
descriptive study
* uNGAL measurement: 24-hour urine
was collected After that, the volume of urine
was measured before collecting 1 mL sample for testing purpose uNGAL was measured by the sandwich ELISA method using NGAL monoclonal antibody in the NGAL kit After that, the sample will be analyzed by Achitech System of Abbott, America to measure uNGAL concentration
* Diagnostic criteria: KDIGO definition
and classification of AKI [5]
- Diagnostic criteria for AKI: Serum creatinine increases ≥ 0.3 mg/dL (26.4 μmol/L compared to basic creatinine within
48 h or urine volum < 0.6 mL/kg BW/hour
at least 6 hours
- AKI degree:
+ AKI degree 1: serum creatinine from
< 220 μmol/L
+ AKI degree 2: serum creatinine from
220 - 353.6 μmol/L
+ AKI degree 3: ≥ 353.6 μmol/L
* Statistical analysis:
Statistical analyses were conducted using SPSS 20.0
RESULTS AND DISCUSSIONS
Table 1: uNGAL concentration in study
group
Index
Control group (n = 51)
Study group (n = 96)
p
uNGAL (ng/mL)
10.74 ± 5.18
412.26 ±
The average concentration of uNGAL in study group was 412.26 ng/mL which was significantly higher than in control group (10.74 ng/mL) with p < 0.001 The maximum
Trang 3and minimum concentration of uNGAL was
1292.38 and 69.63 ng/mL, respectively
With the range of urinary NGAL from 43.62
to 114.66 ng/mL, all of the AKI patients
(100%) had uNGAL elevation Study by Au
V also showed that the mean immediate
postoperative uNGAL levels in patients who
developed sustained AKI were 204.8
ng/mL, and significantly higher than those
who had normal renal function (31.9 ±
113 ng/mL) with p < 0.001 [1] This result
was similar to other studies by Geus H.R,
Makris K, Zappitelli M: there was a
significant higher of uNGAL concentration
in patients who diagnosed AKI compared
with non-AKI patients with p < 0.05 [6, 7, 8]
These differences in uNGAL concentration
were expected because kidney injury
associated with primary renal insults may
be more severe than that in most patients
included in our study, but our patients
were probably more severely ill
In current clinical practice, the gold
standard for identification and classification
of AKI is dependent on serial serum
creatinine measurements, which are
especially unreliable during acute
changes in kidney function We identified
uNGAL as one of the most upregulated
genes in the kidney soon after ischemic
injury NGAL protein was also markedly
induced in kidney tubule cells and easily
detected in the plasma and urine in animal
models of ischemic and nephrotoxic AKI
The expression of uNGAL protein was
also dramatically increased in kidney
tubules of humans with ischemic, septic,
and post-transplant AKI Importantly,
NGAL in the urine was found to be an
early predictive biomarker of AKI in a variety of acute clinical settings Emerging experimental and clinical evidence indicated that in the early phases of AKI from diverse etiologies, NGAL accumulates within two distinct pools, namely, a renal and a systemic pool Gene expression studies in AKI have clearly demonstrated rapid and massive upregulation of NGAL mRNA in the thick ascending limb of Henle's loop and the collecting ducts, with resultant synthesis of NGAL protein in the distal nephron (the renal pool) and secretion into the urine where it comprises the major fraction of uNGAL
This finding also confirms the need for future research to evaluate uNGAL in different renal disease subgroups in order
to understand fully how best to use uNGAL
to diagnose AKI
Table 2: Relation between urine NGAL
concentration and the causes of AKI (n = 96)
Causes n Urine NGAL (ng/mL)
(5) and others < 0.01
In our study, sepsis was the most common cause with the proportion of 60.4% There was no significant difference between these causes with p > 0.05 Our result was similar to study by Vaidya D.S: there was no significant difference between uNGAL concentration and several causes
Trang 4of AKI in these studies (p > 0.05) [10], but
was different with studies by Di Nardo M
and Geus H.R (there was a significant
higher concentration of uNGAL in septic
AKI patients than non-septic AKI patients
with p < 0.001 [4, 6] Lipoproteins also
have strong affinity that trigger an innate
immune response Therefore, it could be
postulated that these circulating ligands
that are linked to tubular epithelial TLR
activation are responsible for the increased
uNGAL concentrations, which we observed
in patients with sepsis However, there
were no increases in their SCr levels
However, recent studies in patients with
sepsis, septic shock, and systemic
inflammatory response syndrome has
reported contradictory findings A possible
explanation for this difference is the
variability of the subject inclusion time
(up to 48 h after ICU admission) Intensive
resuscitation and the administration of
antibiotics may have already occurred
before study inclusion, therefore most likely
inducing rapid changes of uNGAL values
Table 3: Relation between urine NGAL
concentration and AKI category (n = 96)
(ng/mL)
In our study, category of anuria occupied
32.3% all of AKI patients The concentration
of uNGAL was significantly higher in anuria
group compared with non-anuria group
(558.32 ng/mL compared with 342.6 ng/mL)
with p < 0.01 Our findings highlight the
mechanistic insights of NGAL levels
based on the specimens being measured Urine NGAL is proposed to derive predominantly from local renal synthesis
of NGAL in the thick ascending limb of the loop of Henle and the collecting ducts when under inflammatory and oxidative stress Therefore, the concentration of uNGAL was directly related to the renal tubule injury in AKI patients as well as urine excretion ability
Table 4: Relation between uNGAL
concentration and stage of AKI (n = 96)
AKI stages
Urine NGAL (ng/mL)
pAnova
< 0.001
p 1-2 , p 1-3 < 0.001,
p 2-3 = 0.002
According to the KDIGO classification, the stage 1 AKI in our study made up the highest proportion (70.8%) Stage 2 and 3 occupied smaller proportion (21.9% and 7.3%, respectively) Our results also pointed that patients’ uNGAL concentrations at the time of ICU admission were significantly related to their KDIGO stage (p < 0.001) This result was similar to the study by Geus H.R (p < 0.0001) and Zapittelli M (p < 0.0002) when research on the relation between uNGAL and RIFFLE stage [6, 8] NGAL fulfills a central role in regulating epithelial neogenesis, and in iron chelation and delivery after ischemic or toxic insults
to the renal tubular epithelium After kidney injury, NGAL is rapidly expressed on the apical epithelial membranes of the distal nephron NGAL is excreted in the urine
Trang 5through exocytosis and has local
bacteriostatic and proapoptotic effects
Therefore, uNGAL concentration had a
positive relation with the level of renal
damage which exhibited throughout the
high stage of KDIGO classification
Table 5: Correlation between uNGAL and
serum urea, creatinine concentration (n = 96)
Indexes
uNGAL
Correlation equation
169.141
- 150.730
In our study, uNGAL had a moderate
positive relationship with serum urea
concentration (r = 0.529, p < 0.001) and a
strong positive linear relationship with
serum creatinine concentration (r = 0.852,
p < 0.001) Boglignano D also pointed
that a significant correlation was also found between serum creatinine and uNGAL (r = 0.399, p < 0.001) [2] NGAL has mainly been studied in the setting
of acute renal failure Patients who experienced acute renal dysfunction showed
a marked increase in uNGAL levels, which preceded the increase in serum creatinine by a day In a single case of acute tubular necrosis due to heart failure induced hypotension, NGAL tubular expression was reported to be strongly increased [3] Hence, measurements of NGAL may serve as a very early marker of worsening renal function Urinary (or plasma) NGAL levels could therefore be used to adjust therapy, to anticipate and possibly prevent expected renal injury, even before a peak in serum creatinine occurs This potential of NGAL needs to be explored further in future studies
uNGAL = 17.304 x ure + 169.141
0
200
400
600
800
1000
1200
1400
1600
1800
Ure
Chart 1: Correlation between urine NGAL and urea concentration
Trang 6uNGAL = 2.616 x creatinin - 150.730
0
500
1000
1500
2000
2500
Serum creatinin
Chart 2: Correlation between urine NGAL and creatinine concentration
CONCLUSIONS
In our study, all of the AKI patients
(100%) had urine NGAL elevation The
average concentration of uNGAL in our
study group (412.26 ng/mL) was significantly
higher than in control group (10.74 ng/mL)
with p < 0.001 There was no significant
difference between AKI causes and
uNGAL concentration with p > 0.05 The
concentration of uNGAL was significantly
higher in oliguria group compared with
non-oliguria group (558.32 ng/mL compared
with 342.6 ng/mL) with p < 0.005 Patients’
uNGAL concentrations at the time of ICU
admission were significantly related to
their KDIGO stage (p < 0.001) Urinary NGAL
had a moderate positive relationship with
serum urea concentration (r = 0.529,
p < 0.001) and a strong positive linear relationship with serum creatinine concentration (r = 0.852, p < 0.001)
REFFERENCES
1 Au V et al Urinary neutrophil
gelatinase-associated lipocalin (NGAL) distinguishes sustained from transient acute kidney injury after general surgery KI reports 2016, 1 (1), pp.3-9
2 Bolignano D et al Neutrophil
gelatinase-associated lipocalin (NGAL) as a marker of
kidney damage American Journal of Kidney
Diseases 2008, 52 (3), pp.595-605
3 Damman K et al Urinary neutrophil
gelatinase associated lipocalin (NGAL),
a marker of tubular damage, is increased in patients with chronic heart failure European Journal of Heart Failure 2008, 10 (10), pp.997-1000
Trang 74 Di Nardo M et al Impact of severe
sepsis on serum and urinary biomarkers of
acute kidney injury in critically Ill children: An
observational study Blood purification 2013,
35 (1-3), pp.172-176
5 Disease K Improving global outcomes
(KDIGO) acute kidney injury work group: KDIGO
clinical practice guideline for acute kidney
injury Kidney Int Suppl 2012, 2, pp.1-138
6 Geus H.R.H.D et al Neutrophil gelatinase-
associated lipocalin at ICU admission predicts
for acute kidney injury in adult patients
American Journal of Respiratory and Critical
Care Medicine 2011, 183 (7), pp.907-914
7 Makris K et al Urinary neutrophil
gelatinase-associated lipocalin (NGAL) as an
early marker of acute kidney injury in critically ill multiple trauma patients, in Clinical Chemistry and Laboratory Medicine 2009, p.79
8 Zappitelli M et al Urine neutrophil
gelatinase-associated lipocalin is an early marker of acute kidney injury in critically ill children: a prospective cohort study Critical Care 2007, 11 (4), p.R84
9 Chertow G.M et al Acute kidney injury,
mortality, length of stay, and costs in hospitalized patients J Am Soc Nephrol 2005, 16 (11), pp.3365-3370
10 Vaidya V.S et al Urinary biomarkers
for sensitive and specific detection of acute kidney injury in humans Clin Transl Sci 2008,
1 (3), pp.200-208