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Anteprima

ESTRATTO DOCUMENTO

Diagnosis of AMI in the Troponin Era

Based on ESC/ACC’s redefinition of MI

(JACC, 2000)

Typical rise and fall of Troponin or CKMB

with one of the following:

Ischemic symptoms

Development of Q wave on ECG

ST-segment elevation/depression

Coronary artery intervention

Pathologic (morphologic) findings of AMI

Myoglobin

Oxygen binding protein of cardiac and

skeletal muscle (MW=17,800 Da)

Rapid release from infarcted area over

some limited time, rapid transport to

serum

May rise significantly within 1-2 h of

muscle cell damage and after onset of AMI

Rapid renal clearance, return to normal

level within 24 h ↑Myoglobin

Conditions for

Acute myocardial infarction

Open heart surgery

Skeletal muscle damage, muscular

dystrophy, inflammatory myopathies

Renal failure, severe uremia

Shock and trauma

Clinical Usefulness of Myoglobin

Slow technology (RIA) in the past had

limited extensive clinical use as a

cardiac marker

Rapid monitor of success of

thrombolytic therapy

Negative predictor of MI

↑myoglobin

Due to poor specificity,

levels do not always predict

myocardial injury

Marker Responses to MI

B A = myoglobin or CKMB isoforms

B = cardiac troponin

A C = CKMB

A D = cardiac troponin after

unstable angina

C

A D

Brain natriuretic peptide (BNP)

Both BNP and NT-proBNP levels in the blood are used for screening,

• diagnosis of acute congestive heart failure (CHF) and may be useful to

establish prognosis in heart failure, as both markers are typically higher in

patients with worse outcome.

The plasma concentrations of both BNP and NT-proBNP are also typically

• increased in patients with asymptomatic or symptomatic left ventricular

dysfunction.

There is no level of BNP that perfectly separates patients with and without

• heart failure.

BNP: albero decisionale

Paziente con dispnea

Esame obiettivo, Rx torace, ECG

livelli di BNP

BNP <100 pg/mL BNP 100-500 pg/mL BNP >500 pg/mL

HF molto improbabile Sospetto clinico di HF o HF molto probabile

(2%) storia pregressa di HF? (90%)

HF probabile (90%)

Valore soglia di BNP raccomandato 100 pg/mL

Biomarkers: AMI versus AKI

AKI: A Common, Serious Problem

• AKI is present in 5% of all hospitalized patients, and

up to 30% of patients in Intensive Care Units (ICUs)

• The incidence is increasing at an alarming rate

• Mortality rate >50% in dialyzed ICU patients

• 25% of ICU dialysis survivors

progress to end stage

renal disease within 3 yrs % of all “ discharged dead”

” with a diagnosis of ARF

dead

1979: 1.5% 2002: 15.7%

Acute Kidney Injury (AKI)

Stadio Criterio della creatininemia Criterio della diuresi

≥ < 0,5 ml/Kg/h per > 6 h

1 Incremento della creatininemia 0,3

mg/dl oIncremento dei valori basali di

creatininemia compreso tra il 150 e il

200% (1,5 – 2 volte) < 0,5 ml/Kg/h per > 12 h

2 Incremento della creatininemia rispetto

ai valori basali compreso tra il 200 e il

300% (2‐3 volte) < 0,3 ml/Kg/h per 24 h o

3 Incremento della creatininemia rispetto anuria per 12 h

al valore basale > 300% (> 3 volte) o

creatinininemia 4,0 mg/dl con un

incremento acuto > 0,5 mg/dl AKI Network

Achilles Heel

Early diagnosis has been the ‘ Achilles heel ’

of acute kidney injury (AKI) that has

prevented successful implementation of

treatment strategies

To date, pharmacological intervention has

been largely unsuccessful or equivocal, and

morbidity and mortality associated with AKI

have remained unacceptably high

Despite their well

- known limitations, the

most widely used biomarkers for the early

diagnosis of AKI are serum creatinine

,

blood urea nitrogen and urine output

Development of new biomarkers is

imperative!

Some Questions …

9 What is a biomarker?

9 Which is the need for biomarkers

in AKI?

9 Which may be the role of

biomarkers in AKI?

9 Are there examples of promising

AKI biomarkers?

9 Which is the input from new

technologies?

How Many Types of Biomarkers?

Proteins Electric Signals Neuro-imaging

Troponin I ECG TAC

Gene Expression Proteomic Pattern

Microarray Urine Proteome SELDI-TOF

Definition of Biomarker

Medical Subject Heading (MeSH) term, 1989

Biological marker (biomarker)

• A characteristic that is objectively measured and evaluated as an indicator of

normal biological processes, pathogenic processes, or pharmacological responses

to a therapeutic intervention

Type 0 biomarker

• A marker of the natural history of a disease that correlates longitudinally with

known clinical indices

Type 1 biomarker

• A marker that captures the effects of a therapeutic intervention in accordance with

its mechanism of action

Surrogate end point (type 2 biomarker)

• A marker that is intended to substitute for a clinical end point (i.e. s-Creat doubling);

a surrogate end point is expected to predict clinical benefit (or harm or lack of

benefit) on the basis of epidemiological, therapeutic, pathophysiologic, or other

scientific evidence

Biomarkers Definitions Working Group, NIH, 2001

Clin Pharmacol Ther

Biomarkers: AMI versus AKI

Acute Kidney Injury

Acute Myocardial Infarction

Period Serum creatinine

1960s LDH Serum creatinine

1970s CPK, myoglobin Serum creatinine

1980s CK - MB

CK-MB Serum creatinine

1990s Troponin T Serum creatinine

2000s Troponin I

Multiple Therapies Supportive Care

50% ↓ Mortality High Mortality

Diagnosis of AKI is often delayed!

Which is the need

for biomarkers in AKI?

• Elevation in serum creatinine is the current gold standard,

but this is problematic

• Normal serum creatinine varies widely with age, gender,

diet, muscle mass, muscle metabolism, medications, and

hydration status

• In AKI, serum creatinine can take several days to reach a

new steady state

• Up to 50% of kidney function may be lost before serum

creatinine even begins to rise

Diagnosis of AKI is often delayed!

Which Role for Biomarkers in

AKI?

9 Early prediction and diagnosis of AKI (before increase in serum

creatinine)

9 Identify the primary location of injury (proximal tubule, distal

tubule, interstitium, vasculature)

9 Pick out the duration (Prerenal, AKI, CKD) and severity

9 Identify the etiology of AKI (ischemic, septic, toxic, combination)

9 Differentiate from other types of kidney disease (UTI, GN, IN)

9 Predict the outcome (need for RRT, length of hospitalization,

mortality)

9 Monitor response to intervention and treatment

9 Critical Path to

Expedite the drug development process New Medical Products,

FDA 2004

Ideal Biomarker

in AKI assessment at bedside

1. Noninvasive and easy to perform at the bedside or

in a standard clinical laboratory, using easily

accessible samples such as blood or urine

2. Rapidly and reliably measurable using a

standardized assay platform (i.e. ELISA)

3. Highly sensitive to facilitate early detection with a

wide dynamic range and cut-off values (risk

stratification)

Biomarkers: From Bench To

Bedside

Phase Terminology Action Steps

Discover biomarkers in tissues or body fluids

Phase 1 Preclinical Discovery • Confirm and prioritize promising candidates

• Develop and optimize clinically useful assay

Phase 2 Assay Development • Test on existing samples of established disease

• Test biomarker in completed clinical trial

Phase 3 Retrospective Study • Test if biomarker detects the disease early

• Evaluate sensitivity, specificity, ROC

• Use biomarker to screen population

Phase 4 Prospective Screening • Identify extent and characteristics of disease

• Identify false referral rate

• Determine impact of screening on reducing

Phase 5 Disease Control • disease burden

Modified from Pepe MS et al, 2001

J Natl Cancer Inst

“ Storici

” Biomarker Urinari di Danno Renale

Netti GS et al, 2008

G Ital Nefrol

NGAL

N G A L

• eutrophil elatinase- ssociated ipocalin

• First identified as a neutrophil granule protein

• Normally very small amounts in kidney tubules

• The most upregulated gene in the kidney by gene chip analysis,

very early after ischemic or nephrotoxic AKI in animals

NGAL before … … and after 30min ischemia … Mouse Ischemia (30 min)

• S creat ↑ 24 h

• Kidney NGAL ↑ 3 h

• Colocalize with PCNA

• (proliferating cell nuclear antigen)

NGAL/PCNA

Mishra J et al, 2003; Mishra J et al, 2004

J Am Soc Nephrol. J Am Soc Nephrol.

NGAL acts as an acute phase protein which

is rapidly released upon kidney injury

• Human adults in ICUs with ARF (sepsis, ischemia, or nephrotoxins) displayed

>10-fold increase in plasma NGAL and >100-fold increase in urine NGAL,

when compared with normal controls (Intense cortical tubular NGAL staining)

Mori K et al, J Clin Invest. 2005

2-6 h Ι

(µg/L) ARF

• NGAL is a biomarker for AKI after cardiac surgery in Ι without ARF

NGAL

children Urine

Mishra J et al, Lancet 2005

• In a cohort of adults who developed AKI after cardiac surgery, urinary NGAL

was significantly elevated by 1-3 hrs after the operation

Wegener G et al, Anesthesiology 2006

• NGAL levels in biopsies specimens and in urine after kidney transplantation

clearly predict Delayed Graft Function onset and requirement of RRT

Mishra J et al, Pediatr Nephrol. 2006; Parikh CR et al, Am J Transpl. 2006

Interleukin-18

• Proinflammatory cytokine induced and cleaved in the proximal tubule

after AKI. The active form of IL-18 exits the cell and may enter the urine

after being activated in proximal tubules.

• In mice, urinary IL-18 concentration was increased in ischemic AKI

compared with sham-surgery controls. Melnikov VY et al, J Clin Invest 2001

• Urine IL-18 levels were markedly increased in pts with established AKI

but not in subjects with UTI, CKD, nephritic syndrome, or prerenal

failure (ROC AUC of 95% for the diagnosis of established AKI)

Parikh CR et al, Am J Kid Dis 2004

IL-18 seems to be an excellent tool to differentiate ATN from

other types of acute renal diseases

IL-18 may predict development of AKI,

requirement of RRT and mortality

• In acute respiratory distress syndrome (ARDS) urine IL-18 levels of >100

pg/mg predicted the development of AKI 24 hrs before the serum creatinine

(OR 6.5; ROC AUC 0,73). Urine IL-18 predicted also mortality in ARDS

Parikh CR et al, J Am Soc Nephrol 2005

AKI

• In 137 critically ill pediatric pts, urine IL-18 rose 48h

before SCr in non-septic critically ill children, predicted

severity of AKI and was an independent predictor of Controls

mortality

Washburn KK et al. Nephrol Dial Trasplant 2007

• Urine IL-18 levels at the day of transplant clearly identified cadaveric kidney

recipients who subsequently developed DGF and dialysis requirement

Parikh CR et al, Am J Kid Dis 2004; Parikh CR et al, Am J Transplant 2006

• In children pts after cardiac surgery, urine IL-18 levels increased ~6h and

peaked at >25-fold at 12h. IL-18 was associated with duration of AKI.

Parikh CR, Mishra J et al, Kidney Int. 2006

Cystatin C

• Cysteine protease inhibitor synthesized and released

into the blood at a relatively constant rate by all

nucleated cells

• Freely filtered by the glomerulus, completely

reabsorbed by the proximal tubule, and not secreted

• It is a better predictor of glomerular function than

serum creatinine in patients with chronic kidney

disease Grubb AO, Adv Clin Chem 2000

Cystatin C

• Urinary excretion of cystatin C has been shown to predict the

requirement for renal replacement therapy in patients with established

AKI about 1 day earlier, with an AUC of 0.75

Herget-Rosental S eta l, Clin Chem. 2004

• In the ICU setting, a 50% increase in serum cystatin C predicted AKI 1-

2 days before the rise in serum creatinine, with an AUC of 0.97 and

0.82, respectively Herget-Rosental S eta l, Kidney Int. 2004

Sensitive marker of GFR reduction, not a marker of kidney injury

Early marker of injury when filtration is affected but cannot

differentiate between different types of AKI

KIM-1

• Kidney Injury Molecule-1 is a transmembrane protein

that is highly overexpressed in dedifferentiated

proximal tubule cells after ischemic or nephrotoxic

AKI in animal models Ichimura T et al, J Biol Chem. 1998

• A proteolytically processed domain of KIM-1 may be

easily detected in the urine.

Ichimura T et al, Am J Physiol ren Physiol. 2004

KIM-1: acute tubule injury marker

Immunohistochemistry

Tissue KIM-1 expression:

metalloproteinases Undetectable in normal kidneys

Increased in ischemic ATN

(or toxic injury - 2007)

KI Normal human kidney Acute tubular necrosis

Urinary KIM-1 excretion Western blot ELISA

Han WK et al, 2002

Kidney Int.

KIM-1 is specific to ischemic or nephrotoxic

injury, but is a bad early biomarker

• Urinary KIM-1 level elevation predicted AKI in adults undergoing

cardiopulmonary bypass and in pediatric patients undergoing

cardiac surgery Han WK et al, Kidney Int. 2007

• In hospitalized patients, urinary KIM-1 level possessed an AUC

of 0.61 for the prediction of the composite end point (dialysis or

death) Liangos O et al, J Am Soc Nephrol. 2007

More specific to ischemic or nephrotoxic injury and not signific

antly

affected by CKD or UTI

Limited use as an early biomarker: uKIM - 1 increases 12

- 24h after the insult

The “

Omics

” Era Transcriptomics

Genomics Metabolomics

Proteomics

DNA A single gene

yields a number of

RNA splice variants.

Each produces a

Peptide different protein

which can be post-

translationally

modified and whose

abundance is

regulated as needed.

Monarch butterfly

Monarch butterfly


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DETTAGLI
Corso di laurea: Corso di laurea magistrale in medicina e chirurgia (a ciclo unico - 6 anni)
SSD:
Università: Foggia - Unifg
A.A.: 2012-2013

I contenuti di questa pagina costituiscono rielaborazioni personali del Publisher kalamaj di informazioni apprese con la frequenza delle lezioni di Medicina di Laboratorio - Patologia Clinica e studio autonomo di eventuali libri di riferimento in preparazione dell'esame finale o della tesi. Non devono intendersi come materiale ufficiale dell'università Foggia - Unifg o del prof Ranieri Elena.

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