Chronic Kidney Disease
A progressive, irreversible loss of nephron mass staged by filtration (eGFR) and by damage (albuminuria), in which the surviving nephrons' compensatory hyperfiltration itself accelerates the decline.
In a nutshell
CKD is staged on two axes, eGFR (how much filtration remains) and ACR (how much is leaking), because together they predict progression. Nephron loss causes hyperfiltration in surviving nephrons, which itself drives further sclerosis, and lost renal functions produce a predictable cluster of complications: anaemia, bone disease and acidosis.
Classic presentation
An asymptomatic patient with diabetes or hypertension found to have a persistently reduced eGFR and raised ACR on routine screening bloods.
Key points
- CKD requires abnormalities to persist beyond three months: this is what distinguishes it from AKI.
- Staging uses both eGFR (G category) and ACR (A category); the combination, not either alone, predicts risk.
- Hyperfiltration in surviving nephrons is compensatory but self-destructive, which is why ACE inhibitors/ARBs (lowering intraglomerular pressure) slow progression.
- Anaemia, renal bone disease and metabolic acidosis are predictable consequences of specific lost nephron functions, not random complications.
- Blood pressure and proteinuria control are the two most important modifiable levers for slowing progression.
First-line investigation
eGFR and urine albumin-to-creatinine ratio, repeated to confirm chronicity beyond three months.
First-line management
Control blood pressure and proteinuria with an ACE inhibitor or ARB, manage the underlying cause and cardiovascular risk, and treat complications as they emerge.
Exam traps
- A single low eGFR is not CKD until abnormalities persist beyond three months.
- Proteinuria, not eGFR alone, is often the strongest predictor of progression tested in exam stems.
- Do not stop an ACE inhibitor/ARB for a modest expected rise in creatinine after starting it: a small rise (within accepted limits) reflects the intended haemodynamic effect, not harm.
- Anaemia in CKD is normocytic and due to erythropoietin deficiency, not automatically iron deficiency.
Educational content pending clinical review. Not medical advice.