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Rapid Diagnosis of Acute Kidney Injury – New Biomarkers Tested

How does a doctor determine whether or not an emergency-room patient has acute kidney injury? Using tests currently available in the hospital, this question is often difficult to answer. In many emergency cases, however, early diagnosis of the severity of the disease picture is crucial. A large multicenter study by clinicians of the Experimental and Clinical Research Center (ECRC), a joint cooperation between the Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch and the Charité – Universitätsmedizin Berlin, the Helios Hospital Berlin, and two hospitals in the U.S. has now shown that a urine test for proteins excreted by a damaged kidney helps to swiftly identify high-risk patients (Journal of the American College of Cardiology, online, 9. January 2012)*.

“There are
no typical symptoms for acute kidney injury,” said Professor Kai Schmidt-Ott. “Nevertheless
it is very important for the doctor to rapidly determine whether or not a
patient has acute kidney injury” stressed the nephrologist from the Charité, who
leads a research group at the MDC. Jonathan Barasch, Associate Professor of
Medicine and Cell Biology at Columbia University and senior author of the paper
commented: “When a patient presents to the Emergency Department and a blood
test identifies an abnormal creatinine value, it is difficult to know whether
the patient needs to be hospitalized because of ongoing intrinsic acute kidney injury
(a potentially fatal disease) or whether the patient needs to be sent home
after intravenous or oral fluids and later examined at an outpatient clinic. This
study, based on earlier studies by Professor Thomas L. Nickolas and Professor Schmidt-Ott,
demonstrates the strength of association of the novel biomarker neutrophil
gelatinase- associated lipocalin (NGAL) with intrinsic acute kidney injury and
not simple volume depletion or more indolent forms of chronic kidney disease”,
Prof. Barasch said. “Furthermore, the study demonstrates that NGAL and a second
biomarker, kidney-injury molecule-1 (Kim1), predict poor outcomes during
hospitalization, even days after the initial measurements.”

“In the
initial stage of acute kidney injury, we may have most room for improvement of
our current clinical practice” Professor Schmidt-Ott points out. In cases of advanced
acute kidney injury, dialysis treatment is required. Many patients with severe acute
kidney injury die in the hospital. Statistics illustrate how extensive the
problem is. In the U.S. alone, one million patients are diagnosed every year
with severe acute kidney injury. According to data of the German Society of Nephrology,
there are currently around 70 000 dialysis patients in Germany; and this number
is on the increase.

Currently,
only the serum creatinine level is used for the diagnosis of acute kidney
injury. Creatinine is a molecule that is normally excreted via the kidney, but
accumulates in the blood when kidney function is impaired. “However, an
elevated creatinine level is not a direct measure of kidney damage,” Professor
Schmidt-Ott explained. “Thus, a prolonged slight-hypoperfused kidney can lead
to a significant increase in serum creatinine, although the kidney tissue is
not damaged. This functional impairment of the kidney usually responds well to
treatment. The patients receive an electrolyte solution or have to stop taking
the medications that damage the kidneys. In contrast, tissue damage in the
kidney has a significantly worse prognosis. Nevertheless, serum creatinine
values in the emergency room are of limited value because after kidney damage, 24
to 48 hours may elapse before serum creatinine values accumulate in the blood. Thus,
at-risk patients remain undetected. That is why there is an urgent need for
more accurate biomarkers of tissue damage in the kidney.”

Research
has indicated that damaged kidneys synthesize specific proteins. In previous smaller
studies, researchers investigated whether or not these proteins could serve as
biomarkers to identify high-risk patients with kidney tissue damage. During the
past three years, Professor Nickolas and Professor Barasch (Columbia University)
and Professor Schmidt-Ott and Professor Friedrich C. Luft (both ECRC ), pursued
this question in a large-scale study. The researchers in Berlin and New York
took a single measure of five urinary biomarkers from almost 1700 emergency
room patients upon their admission to the hospital.

The
investigators found that primarily the two putative biomarkers, NGAL and KIM-1,
were useful in providing an early risk assessment. If both NGAL and KIM-1
levels are low, the patient’s risk of dying in the hospital or requiring
dialysis treatment is likewise low. In contrast, high levels indicate the risk
of acute kidney damage. If a doctor bases the diagnosis both on these biomarker
readings and the serum creatinine levels, a more exact assessment of the
individual risk is possible, according to Professor Schmidt-Ott, who is also
adjunct assistant professor at Columbia University. This finding could quickly
help emergency room doctors to devise an adequate treatment strategy for the
patient.

But it is
still not clear whether or not all patients admitted to an emergency room
should be tested for these biomarkers. Perhaps only certain patients, for
example diabetics or patients with high blood pressure, who are at high risk
for acute kidney injury should be included. Furthermore, whether or not these
biomarkers actually influence the individual treatment outcome is uncertain. As
Professor Schmidt-Ott concluded, further studies are needed to answer these
questions.

*Diagnostic and Prognostic Stratification in the Emergency Department
Using Urinary Biomarkers of Nephron Damage - A Multicenter Prospective Cohort
Study

Thomas L. Nickolas*†1, Kai M. Schmidt-Ott*†2,3,
Pietro Canetta1, Catherine Forster1, Eugenia Singer2,3,
Meghan Sise1, Antje Elger2, Omar Maarouf4,
David Antonio Sola-Del Valle1, Matthew O’Rourke1, Evan
Sherman1, Peter Lee1, Abdallah Geara1, Philip
Imus1, Achuta Guddati1, Allison Polland1,
Wasiq Rahman1, Saban Elitok3, Nasir Malik1,
James Giglio1, Suzanne El-Sayegh4, Prasad Devarajan5,
Sudarshan Hebbar6, Subodh J. Saggi4, Barry Hahn4,
Ralph Kettritz2,3, Friedrich C. Luft2,3, and Jonathan
Barasch1

1 Columbia
University College of Physicians and Surgeons, New York, NY, USA

2 Experimental
and Clinical Research Center, a joint cooperation between the Charité Medical
Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany

3 Helios
Clinics, Berlin, Germany

4 Staten
Island University Hospital, Staten Island, NY, USA

5 Cincinnati
Childrens Hospital, Cincinnati, OH, USA

*Co-first and co-corresponding authors

Contact:
Barbara Bachtler
Press Department
Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch
in the Helmholtz Association
Robert-Rössle-Straße 10
13125 Berlin
Phone: +49 (0) 30 94 06 - 38 96
Fax:  +49 (0) 30 94 06 - 38 33
e-mail: presse@mdc-berlin.de
http://www.mdc-berlin.de/
 

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