Chronic kidney disease (CKD)

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Classification | Management

Definition

Chronic Kidney Disease (CKD) is defined as persistent kidney dysfunction for ≥3 months, characterised by:

  • eGFR <60 mL/min/1.73m² on at least two occasions.
  • Markers of kidney damage (e.g., albuminuria, haematuria, structural abnormalities).

Aetiology

Common Causes:

  • Diabetes Mellitus: diabetic nephropathy is the leading cause.
  • Hypertension: chronic high blood pressure damages renal arteries.
  • Glomerulonephritis: autoimmune or post-infectious conditions.
  • Polycystic Kidney Disease (PKD): genetic disorder causing cyst formation.
  • Obstructive Uropathy: prolonged urinary obstruction (e.g., BPH, kidney stones).
  • Chronic Pyelonephritis: recurrent kidney infections.
  • Medications: NSAIDs, lithium, and nephrotoxic drugs.

Pathophysiology

  • Progressive nephron loss leads to glomerular hyperfiltration, causing further renal damage.
  • Loss of kidney function results in fluid overload, electrolyte imbalances, and metabolic acidosis.
  • Compensatory mechanisms eventually fail, leading to end-stage renal disease (ESRD).

Risk Factors

  • Diabetes mellitus (strongest risk factor).
  • Hypertension.
  • Family history of CKD.
  • Obesity and metabolic syndrome.
  • Smoking (accelerates renal decline).
  • Older age (>60 years).
  • Nephrotoxic drug use (e.g., NSAIDs, aminoglycosides).

Signs and Symptoms

Early CKD (Often Asymptomatic):

  • Hypertension.
  • Non specific symptoms (fatigue, poor appetite).
  • Polyuria (due to impaired urine concentration).

Advanced CKD:

  • Oedema: due to fluid retention.
  • Pruritus: accumulation of toxins in the blood.
  • Muscle cramps: electrolyte imbalances.
  • Metabolic acidosis: results in deep, laboured breathing (Kussmaul respirations).
  • Hyperkalaemia: can cause life threatening arrhythmias.

Investigations

  • eGFR (Estimated Glomerular Filtration Rate): calculated using serum creatinine.
  • Urinary Albumin:Creatinine Ratio (ACR): detects proteinuria.
  • Urinalysis: checks for haematuria, proteinuria.
  • Renal Ultrasound: assesses kidney size, cysts, or obstruction.
  • Serum U&Es: monitors potassium, sodium, creatinine.
  • Full Blood Count (FBC): CKD can cause anaemia.
  • Bone Profile: assesses for secondary hyperparathyroidism.

Classification

CKD is staged using eGFR and albuminuria (ACR) categories:

Stage eGFR (mL/min/1.73m²) ACR Category Risk
G1 ≥90 A1 (<3 mg/mmol) Low risk
G2 60–89 A2 (3–30 mg/mmol) Moderate risk
G3a 45–59 A2–A3 (>30 mg/mmol) High risk
G3b 30–44 A2–A3 Very high risk
G4 15–29 A3 Severe risk
G5 <15 A3 End-stage kidney disease

Management

1. Lifestyle Modifications:

  • Low-sodium diet: reduces fluid retention and hypertension.
  • Smoking cessation: slows progression.
  • Exercise: helps manage hypertension and diabetes.
  • Limit NSAID use: avoid nephrotoxic drugs.

2. Pharmacological Management:

  • ACE inhibitors / ARBs: first line to reduce proteinuria and slow progression.
  • Diuretics: manage fluid overload and hypertension.
  • Statins: reduce cardiovascular risk.
  • Sodium bicarbonate: for metabolic acidosis.
  • Iron and erythropoietin: to treat anaemia.

3. Referral to Nephrology:

  • eGFR <30 mL/min/1.73m².
  • Rapid eGFR decline (>25% drop within 12 months).
  • Uncontrolled hypertension despite medications.
  • Proteinuria >70 mg/mmol ACR.

4. End-Stage Management:

  • Dialysis: indicated for eGFR <10 mL/min/1.73m² or refractory symptoms.
  • Kidney Transplant: preferred treatment in eligible patients.
RenalmypanotesChronic kidney disease (CKD)