Scientific Calendar March 2023

Chronic kidney disease (CKD) is defined as ‘persistent abnormalities of the kidney structure and/or function, present for more than three months’ [1] with hypertension, diabetes, and obesity being the main risk factors for the onset and progression of CKD. Since the prevalence of these civilisation diseases has been steadily increasing since the 1990s [2], an increase of the global prevalence of CKD to more than 10 % is not surprising. Besides its individual effects on patients’ quality of life, CKD is putting a significant burden on healthcare expenditures and the society [3]. In Germany, for instance, individual annual costs for treating a patient at stage five reaches an amount of € 45,000 [4] (Fig. 1). Considering the prevalence of CKD and underlying civilisation diseases, frequent screening of risk group patients for the onset of CKD is often recommended by international guidelines, but in reality hardly performed.

Apart from the estimated glomerular filtration rate (eGFR), urinary albumin is a key indicator for the development of CKD. It is essential to distinguish between mildly and severely increased albuminuria. While the early detection of albuminuria at a mildly increased level allows reverting the onset of CKD, severely increased albuminuria is irreversible and the course towards end-stage renal failure is set [5] (Fig. 2).

Under normal conditions, albumin remains in the blood and does not pass the glomerular filtration barrier consisting of endothelial cells of the glomerular blood vessels, the glomerular basement membrane (GBM), and podocytes. In uncontrolled diabetes, elevated blood glucose levels lead to increased levels of glucose in the primary urine, which in turn cause podocytes to produce reactive oxygen species (ROS). ROS then cause apoptosis of the podocytes and a breach of the glomerular filtration barrier, finally leading to albumin passing into the urine (albuminuria) (Fig. 3) [7].

Meanwhile, the laboratory was able to reduce the need for quantitative assessments of albuminuria by up to 80 %, resulting in remarkable cost savings. These savings are directly converted into additional capacities for screening risk group individuals for the onset of CKD. This allows a wider-ranging early detection of CKD, fostering the fight against the burden of CKD (Fig. 5).

Can a test strip-based approach replace quantitative techniques for the early detection of albumin to allow screening of risk group patients for the onset of CKD?

At the University Hospital San Juan (Alicante, Spain), María Salinas and her team investigated the potential of the automated test strip analysis on the UC-3500 to replace quantitative tests. Here, a new workflow was concluded (Fig. 4), with test strip analysis as the default screening for albuminuria. Upon exceeding defined cut-off values (≥ 10 mg/L albumin and ≥ 4.42 mmol/L creatinine), samples are suspicious of an increased albumin:creatinine ratio (ACR) and are finally subjected to quantitative assessment [8].