Caring for kidneys

Xchange newsletter – February 2009

‘Turning Science into Caring’ was the focus of the 4th Annual Abbott European Laboratory Symposium (September 2008, Wiesbaden, Germany). At this symposium, Professor Ronco, a clinical nephrologist from St Bortolo Hospital (Vincenza, Italy), discussed the science and development of the NGAL biomarker.

NGAL

We asked Ian Barlow, consultant biochemist at PathLinks, North Lincolnshire and Goole NHS Foundation Trust for his views on the potential impact of NGAL.

“I’m a clinical biochemist working in a medium sized district general hospital in the UK. Renal failure is an important aspect of our workload. We use markers for both diagnosis and monitoring,” Ian explained.

“Serum creatinine has been in use for more than 100 years as an Acute Kidney Injury (AKI) marker but everyone is aware of its limitations. The emergence of a superior marker, with greater sensitivity and specificity, is very exciting from our standpoint. If NGAL lives up to the potential described by Professor Ronco, the advent of this test would represent a quantum leap forward in what we as biochemists are able to offer our medical colleagues.”

“Professor Ronco stated that, unlike serum creatinine, which takes up to three days to achieve a new steady state, NGAL can appear in urine, as a specific marker for AKI, within 3-12 hours. If this is the case, NGAL will be a great early marker for AKI.”

Ian concluded, “More specific, sensitive, innovative markers, such as NGAL, will undoubtedly have an impact in terms of clinical care and lab medicine over next decade.”

AKI and NGAL [1]

Neutrophil gelatinase-associated lipocalin (NGAL) is a promising new biomarker for the early diagnosis, risk stratification and prognosis of acute kidney injury (AKI). Application of urine NGAL testing, available as a new automated assay for the ARCHITECT system later this year, has the potential to improve patient outcomes and reduce the economic burden of AKI.

Previously known as acute renal failure, AKI is characterised by an abrupt decline in kidney function (oliguria) within hours or days. With an increase in incidence of 50% over the past 30 years, this disease is attributed to more than 4 million deaths per year world-wide and costs the US health services alone over $10 billion annually. As a result, developing of new biomarkers for early detection of AKI has been designated as a top research priority by the American Society of Nephrology.

Urinary NGAL determination has been established as the most promising AKI test because increased NGAL levels in urine occur earlier than those in serum. In comparison with serum creatinine, a clear margin of 1 to 3 days can be gained. Preliminary cut-off values of 130 μg NGAL/g creatinine (14.7 μg NGAL/mmol creatinine) are independent of muscle mass and diet but can be influenced by systemic or urinary tract infections as well as pre-existing renal diseases.

Unlike raised Creatinine or Cystatin C levels which are indirect markers of kidney injury, raised urine NGAL concentrations are a direct response to kidney tubular cell injury.

Reference
[1] 4th Annual Abbott European Laboratory Symposium, Turning Science into Caring, Summary notes, 2008