Categorization of albuminuria in UAB Pediatric Sickle Cell Kidney Cohort. Patients with HbSS and HbSB0 thalassemia ≥ 5 years of age with ACR measurements performed at a steady-state outpatient clinic visit were included. Never albuminuria is defined as no ACR measurements ≥30 mg/g, intermittent albuminuria as 1 of 3, and persistent albuminuria as 2 of 3 consecutive ACR measurements ≥30 mg/g.