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Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status

Plain English Summary

Background and study aims
Acute kidney injury (AKI) occurs when the kidneys suddenly stop working properly. It can cause complete kidney failure which is a very serious condition that can lead to death. It usually occurs after complications from illness or surgeries. AKI occurs in an estimated 36% of patients after a cardiac (heart) surgery. Therefore, people undergoing cardiac surgery are at a higher risk of AKI. However, it is hard to accurately predict the risk of AKI. There are tests that can evaluate renal function (how well the kidney works) by measuring creatinine levels in the kidneys (a type of waste that needs to be filtered by the kidneys to be then eliminated by urine (peeing)). This type of test could be used to see if there are indicators for risk of future AKI. The aim of this study is to examine kidney function prior to surgery is able to predict risk for AKI after surgery.

Who can participate?
Adults over the age of 18 who are undergoing elective cardiac surgery.

What does the study involve?
Participants undergo a kidney stress test prior to their elective cardiac surgery. This test takes seven hours and includes five measurements of serum creatinine (blood samples) and five one-hour urine samples in order to estimate creatinine levels. Participants then have their surgery and are followed up for seven days through daily blood tests to assess creatinine blood levels and by monitoring their urine levels. Three months after surgery, participants undergo another kidney stress test to evaluate renal function.

What are the possible benefits and risks of participating?
There are no notable benefits or risks with participating.

Where is the study run from?
San Bortolo Hospital (Italy)

When is the study starting and how long is it expected to run for?
April 2014 to February 2016

Who is funding the study?
San Bortolo Hospital (Italy)

Who is the main contact?
Dr Faeq Husain-Syed

Trial website

Contact information



Primary contact

Dr Faeq Husain-Syed


Contact details

San Bortolo Hospital
Viale Ferdinando Rodolfi
+39 (0)444 753650

Additional identifiers

EudraCT number number


Protocol/serial number


Study information

Scientific title

Use of preoperative renal function reserve to predict risk of acute kidney injury after cardiac surgery


Study hypothesis

The aim of this study is to see whether preoperative renal functional reserve predicts risk for acute kidney injury after cardiac surgery.

Ethics approval

Ethical Committee of the Province Vicenza Italy, 20/08/2014, ref: n63/14

Study design

Observational cohort study

Primary study design


Secondary study design

Cohort study

Trial setting


Trial type


Patient information sheet

See additional files (in Italian)


Acute kidney injury after cardiac surgery


Participants with normal glomerular filtration rates who are undergoing an elective cardiac surgery are included in this study. Participants undergo a preoperative kidney stress test using high oral protein loads. This is then repeated three months after surgery. The kidney stress test takes seven hours and includes five measurements of serum creatinine and five one-hour urine collection in order to estimate creatinine clearance.

Participants are followed for occurrence of postoperative acute kidney injury (AKI) for seven days after the surgery through daily serum creatinine blood tests and hourly urine output measurements according to the Acute Kidney Injury Guidelines of Kidney Disease Improving Global Outcomes (KDIGO).

Urine samples are taken from participants prior to surgery, thirty minutes after the cardiac bypass, at admission to the intensive care unit, at four, 12 and 24 hours after surgery and when participants are discharged from the hospital in order to examine urinary biomarkers.

Renal function is measured three months after surgery by repeating the kidney stress test.

Intervention type



Drug names

Primary outcome measure

1. Renal functional reserve (RFR) is measured using a high oral protein load kidney stress test at baeline (before cardiac surgery) and three months after surgery
2. Acute kidney injury is measured using KDIGO criteria seven days after surgery

Secondary outcome measures

1. Occurrence of acute kidney injury impact the RFR is measured using Kidney Disease Improving Global Outcomes criteria at three months after surgery
2. Urinary biomarkers (TIMP-2 and IGFBP7) to predict loss of RFR are measured using urine samples at basline, 30 minutes after initiation of cardiopulmonary bypass, at intensive care unit admission, four, 12 and 24 hours after surgery and at hospital discharge

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Older than 18 years
2. Undergoing elective cardiac surgery
3. Signed informed consent forms

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Pregnancy
2. Chronic kidney disease ≥ stage III
3. Solitary kidney
4. Diabetes mellitus type 1
5. Recent cardiac arrest
6. Liver failure or cirrhosis
7. Total parenteral nutrition
8. Hemoglobin <11 g/dl
9. Sepsis
10. History of malabsorption, chronic inflammatory bowel disease, short bowel, or pancreatic insufficiency
11. Transplant donor or recipient
12. Active autoimmune disease with renal involvement
13. Rhabdomyolysis
14. Prostate hypertrophy with International Prostate Symptom Score ≥20
15. Neoplasm

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

San Bortolo Hospital, Department of Cardiac Surgery
Via Rodolfi 37

Sponsor information


International Renal Research Institute

Sponsor details

San Bortolo Hospital
Department of Nephrology
Dialysis and Transplantation
Viale Ferdinando Rodolfi
+39 (0)444 753650

Sponsor type

Research organisation



Funder type

Hospital/treatment centre

Funder name

San Bortolo Hospital Italy

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

It is planned for publication in a high-impact peer reviewed journal.

IPD sharing plan:
The datasets generated during and/or analysed during the current study are/will be available upon request from Dr Faeq Husain-Syed at

Intention to publish date


Participant level data

Available on request

Basic results (scientific)

Publication list

2018 results in:

Publication citations

Editorial Notes

30/07/2018: Publication reference added.