Renal insufŠciency or renal or kidney failure is a clinical condition caused by several pathologic entities that cause a deterioration of renal function, adaptation, and eventually uncompensated renal failure. The disease can be classiŠed qualitatively into three groups according to the severity of the functional impairment: (1) decreased renal reserve, (2) renal insufŠciency, and (3) uremia. The disease can be classiŠed quantitatively according to the estimated glomerular Šltration rate (eGFR) as follows:
• Stage 1: evidence of kidney damage but normal eGFR: ≥90 • Stage 2: mildly decreased eGFR: 60-89 • Stage 3: moderately decreased eGFR: 30-59 • Stage 4: severely decreased eGFR: 15-29 • Stage 5: kidney failure eGFR: <15
Early evidence of kidney damage, before the eGFR decreases, includes microscopic hematuria and/or proteinuria. The albumin-to-creatinine ratio in a spot urine sample is a useful test to screen for early kidney damage in patients at risk of kidney disease such as those with diabetes or hypertension. The normal albumin/creatinine ratio is <30 μg/mg; values of 30-299 indicate microalbuminuria and values of ≥300 indicate macroalbuminuria.