Metals in urine could detect acute kidney injury in very early stages

Metals in urine could detect acute kidney injury in very early stages
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Certain metals in urine could provide useful insight into clinical biomarkers for acute kidney injury in the early stages.

Acute kidney injury is a sudden episode of kidney failure or kidney damage that occurs rapidly within a few hours or days. It occurs as a result of a build-up of waste products in the blood, leading to difficulty balancing fluid in the body. The onset of this condition can lead to damage to the brain, heart and lungs. It is a common injury, occurring in 10-20% of patients in hospital and can be instigated by serious illness and trauma. Symptoms can vary, however, confusion, chest pain and too little urine leaving the body are signs of acute kidney injury.

Scientists from the University of Nottingham’s School of Veterinary Medicine and Science and clinicians from Nottingham University Hospitals NHS Trust have discovered potentially useful biomarkers that could detect acute kidney injury.

The study is published in Kidney International Reports.

Addressing the detection needs for acute kidney injury

It is widely understood that an ongoing problem in managing acute kidney injury is the inability to detect it at an early stage. Many cases of the disease are potentially avoidable, or the severity and consequences may be reduced with early detection.

Current detection practises for acute kidney injury are a rise in a blood test, serum creatinine or by a fall in urine output. The downfall of these methods is it takes over 24 hours from the time of kidney damage to reveal a problem, allowing the disease to worsen. This has led to a clinical need to develop better tests for the early detection of the disease.

Scientists have previously reported a pig model of kidney injury that replicates many features of a human acute kidney injury. Using this model allowed them to identify certain urinary metals that could have the potential to clinically detect the disease.

Metal biomarkers for detection

To test their hypothesis, the scientists used two clinical groups at risk of acute kidney injury. They found that concentrations of the metals rose in urine from the patients with the disease within an hour after cardiac surgery and were elevated on admission to intensive care.

The biomarkers alone and in combination (e.g., the product of Zn × Cu) had good sensitivity for early identification of patients at risk of moderate to severe acute kidney injury. The researchers found that a particularly high negative predictive value suggested additional efficacy in identifying patients at low risk of the disease.

Urinary Cd, Cu and Zn were useful biomarkers compared to other biomarkers. They were unaffected by comorbidity, proteinuria, sex or age. The urinary metals are stable at room temperature, which is useful for remote care settings.

“This study is the culmination of 10 years of work at Nottingham and is an example of how collaboration between animal scientists, clinicians and local companies can each utilise their expertise to make new and unique discoveries. It is our hope that the research can now be developed further by industry to truly move these discoveries from lab bench to bedside,” commented David Gardner, Professor of Physiology at the University of Nottingham.


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