Definition and Staging

•    CKD is defined as:

o    Abnormalities in kidney structure or function >3 months (e.g. ↓ eGFR, albuminuria, structural anomalies)

•    Staging based on eGFR (mL/min/1.73 m²):

o    Stage 1: ≥90 + evidence of renal damage (e.g. proteinuria, imaging)

o    Stage 2: 60–89 + evidence of damage

o    Stage 3a: 45–59

o    Stage 3b: 30–44

o    Stage 4: 15–29

o    Stage 5: <15 (end-stage renal disease, ESRD)

•    Albuminuria grading (ACR):

o    A1: <3 mg/mmol

o    A2: 3–30

o    A3: >30

Common Causes of CKD

•    Diabetes mellitus (most common)

•    Hypertension

•    Glomerulonephritis (e.g. IgA nephropathy)

•    Polycystic kidney disease

•    Obstructive uropathy (e.g. BPH, stones)

•    Chronic pyelonephritis

•    Vascular disease (e.g. renal artery stenosis)

Complications of CKD

•    Anaemia of chronic disease

o    Normocytic, normochromic due to ↓ erythropoietin

o    Contributing factors: inflammation, iron deficiency, bleeding

o    Rx: erythropoiesis-stimulating agents (ESAs), iron (IV/oral)

•    CKD–Mineral and Bone Disorder (CKD-MBD)

o    ↓ 1α-hydroxylation of vitamin D → ↓ Ca²⁺ → ↑ PTH (secondary hyperparathyroidism)

o    Features: bone pain, fractures, vascular calcification

o    Labs: ↑ PTH, ↑ phosphate, ↓ calcium, ↑ ALP

o    Rx: phosphate binders, vitamin D analogues (e.g. calcitriol), cinacalcet

•    Cardiovascular risk

o    Major cause of mortality in CKD

o    Risk factors: HTN, dyslipidaemia, anaemia, inflammation

o    ↑ risk of: LV hypertrophy, heart failure, MI, stroke

o    Rx: BP control (target <130/80), statins, antiplatelets if indicated

•    Electrolyte and acid–base disturbances

o    Hyperkalaemia, metabolic acidosis, hyponatraemia, hypocalcaemia

o    Require dietary restriction, bicarbonate supplementation

•    Fluid overload

o    Oedema, hypertension, pulmonary congestion

o    Salt and fluid restriction, loop diuretics

•    Uraemia

o    Symptoms: nausea, anorexia, pruritus, pericarditis, encephalopathy

o    Dialysis indicated if symptomatic

Renal Replacement Therapy (RRT)

•    Indications:

o    ESRD (CKD 5) or refractory complications (e.g. hyperkalaemia, acidosis, fluid overload)

•    Haemodialysis

o    Most common modality

o    Requires arteriovenous (AV) fistula (takes ~6 weeks to mature)

o    Schedule: typically 3×/week

o    Risks: hypotension, infection, dialysis disequilibrium syndrome

•    Peritoneal Dialysis

o    Continuous Ambulatory Peritoneal Dialysis (CAPD) or Automated (APD)

o    Performed at home; uses peritoneum as semi-permeable membrane

o    Risks: peritonitis (cloudy dialysate, abdominal pain), exit site infections, inadequate clearance

•    Renal Transplantation

o    Best long-term option for eligible patients

o    Types: living related, living unrelated, deceased donor

o    Requires lifelong immunosuppression (e.g. tacrolimus, mycophenolate, steroids)

o    Risks:

    Acute rejection: T-cell mediated, occurs days–months post-op

    Chronic rejection: interstitial fibrosis and tubular atrophy

    Infections: CMV, BK virus

    Drug toxicities: calcineurin inhibitors (CNI) → nephrotoxicity, hypertension, diabetes