Non-invasive Testing for End-Stage Chronic Kidney Disease

The adequacy of dialysis treatment is traditionally assessed by measuring serum urea and calculating Kt/V, which requires venous blood sampling and laboratory infrastructure. This observational diagnostic study evaluates the use of a portable, bioelectronic point-of-care test (KF4+, Gisens Biotech) for measuring urea and potassium in capillary blood as a non-invasive alternative. KF4+ test is a disposable cartridge based on electrochemical detection of analytes inside. Adult patients with end-stage renal disease undergoing chronic hemodialysis from Hospital Interzonal General de Agudos "General San Martín" are enrolled. Capillary blood samples are collected before and after dialysis sessions and analyzed using the KF4+ digital test. Venous blood samples collected at the same time points are analyzed using standard hospital laboratory reference methods with the autoanalyzer Wiener Lab CMD 800i. Method comparison analyses are performed to evaluate agreement and correlation between capillary and venous measurements. Dialysis efficiency is assessed by calculating Kt/V using urea values obtained from capillary blood and comparing these results with Kt/V calculated from venous blood measurements. The study is conducted at a single hospital center and follows a paired, comparative, observational design. KF4+ results were not used for clinical decision-making.