Clinical assessment of kidney function and prognosis in adults

Kidney function assessment is clinically relevant in many settings for clinical outcomes and drug dosing. Medications, nitrogenous waste products and other uraemic toxins all accumulate as kidney function falls. Endogenous waste product accumulation allows for a clinically relevant estimate of glomerular filtration rate (eGFR). A fall in eGFR is associated with developing not only end-stage kidney disease but also the risk of all-cause mortality, hospitalization and cardiovascular disease. Worse outcomes have been associated with cancer and infection, including COVID-19. Therefore accurate, timely and cheaper assessment of kidney function is key to prognosis for many diseases and in ensuring medication achieves a therapeutic, non-toxic level. Assessment of the glomerular filtration barrier provides further diagnostic information in the form of albuminuria and proteinuria measurement Although direct GFR measurement and kidney biopsy give detailed information on the filtration rate and glomerular barrier, regularly repeated measurement and sampling is impractical and of significant risk. Methods have been developed to estimate kidney function in the form of eGFR and proteinuria measurement. Prognostic tools such as the Kidney Failure Risk Equation have undergone extensive validation studies and are being used in clinical practice to support patient risk counselling and guide referrals into secondary care.