ALB and chronic kidney disease: CKD is classified into zero to seven stages (stages of 0, 1, 2, 3a, 3b, 4, and 5) according to estimated glomerular filtration rate (eGFR) and kidney damage such as proteinuria (>200 mg/day or protein to creatinine ratio >200 mg/g creatinine) or albuminuria (urinary albumin excretion ≥30 mg/day or albumin to creatinine ratio ≥30 mg/g creatinine).