Why is it important to include urinary albumin excretion in the definition of CKD?
Urinary albumin measurement is the most abundant protein lost in the urine, and its measurement is more standardized than that of urinary total protein.
Albuminuria is a risk factor for the development of end-stage kidney disease (ESKD) in the general population, and a powerful predictor of kidney outcomes in CKD patients, with prognosis being worse with higher levels of albuminuria.
Nephrotic range proteinuria (ACR > 2200 mg/g) is associated with even higher risks. Reduction of proteinuria in clinical trials is usually, but not always, associated with improved kidney outcomes.