Chronic Kidney Disease: Staging and Complications

Chronic kidney disease (CKD) is defined as abnormalities of kidney structure or function, present for a minimum of 3 months, with implications for health. The definition has two working parts: a time element and a consequence element. A single abnormal result proves neither, because it could reflect a recent acute kidney injury (AKI). CKD may be identified by: - eGFR below 60 mL/min/1.73 m² for at least three months. - Persistent albuminuria. - Abnormal urine sediment. - Structural kidney abnormalities. - Histological abnormalities. - Other recognized markers of kidney damage. CKD can therefore exist with a normal or near-normal eGFR when persistent markers of kidney damage are present. A single elevated creatinine does not establish CKD. The prescriber establishes the diagnosis and the classification; the RN gathers the trends, recognizes what they suggest and escalates what is dangerous. ### The mental model: fewer nephrons doing more work The kidney filters, regulates and manufactures. CKD erodes all three jobs, and every CKD complication traces back to one of them. Progressive nephron injury reduces the functioning nephron mass. The remaining nephrons compensate...