Waikar SS, et al. - Researchers determined short-term within-person variability of estimated glomerular filtration rate (eGFR) or albuminuria in the setting of clinically stable outpatients with chronic kidney disease (N = 50; mean age, 56.8 years; median eGFR, 40 mL/min/1.73 m²; median urinary albumin-creatinine ratio (UACR), 173 mg/g). In this cross-sectional study with multiple collections over less than 4 weeks, relatively low short-term within-person variability in eGFR markers was seen, whereas albuminuria appeared to have high variability, making it difficult to distinguish random variability from meaningful biologic changes.