Chronic Kidney Disease

“Chronic reduction in renal function (over 3 months). Progressive and generally irreversible.”

Risk Factors

• Modifiable:
  • Smoking
  • Medications that affect Kidney function
• Non-Modifiable:
  • Older Age
  • Hypertension
  • Diabetes
  • Underlying Kidney disease – Polycystic kidney disease, chronic glomerylonephritis, chronic pyelonephritis.

Aetiology

• Commonly caused by co-existing underlying conditions, including:
  • Diabetes (diabetic nephropathy)
  • Hypertension
  • Chronic glomerulonephritis
  • Autosomal dominant polycystic kidney disease (ADPKD)
  • Chronic pyelonephritis

Pathophysiology

Nephron loss → nephron hypertrophy & ­↑ arterial pressure → ­­↑ glomerular pressure & hyperfiltration → glomerulosclerosis → further nephron loss (vicious cycle)

Clinical Presentation

• Usually diagnosed on routine testing and symptoms occurring by stage 4:
  • Uraemia – Pruritis, weight loss, confusion, paresthesia, lethargy, pale skin
  • Protein loss & Na retention – polyuria, polydipsia, oliguria, shortness of breath
  • Hyperkalaemia – palpitations, arrhythmias (tall T waves and widened QRS)
  • Acidosis – SOB, confusion, Kussmaul’s respiration for compensation
  • Anaemia – SOB, lethargy, faintness, tinnitus, pallor, tachycardia
  • Vitamin D deficiency – renal osteodystrophy, bone pain, osteomalacia
  • Hypercalcaemia – bone pain, excessive thirst, digestive problems, weakness

Investigations

• Bloods:
  • Urea and Electrolytes – eGFR used to diagnose and stage CKD. 2 tests over 3 months required.
• Imaging:
  • Bone X-Ray – Any renal osteodystrophy?
  • Abdominal X-Ray – any calcification from stones?
• Special:
  • Urinalysis – assess for haematuria (1 + significant)
  • Albumin: creatinine ratio (ACR) – assess for proteinuria (dipstick not sufficient).
    • ACR 30-300mg/g for >3 months indicates CKD

Diagnosis

CDK Stage	GFR range (ml/min)	Kindey Damage
Stage 1	>90	Some sign of kidney damage on other tests
Stage 2	60-90	Some sign of kidney damage on other tests
Stage 3a	45-59	Moderate Reduction
Stage 3b	30-44	Moderate Reduction
Stage 4	15-29	Severe Reduction
Stage 5	<15	Establised Renal Failure → Dialysis or Kidney transplant may be needed.

If there is no sign of kidney damage (e.g. no proteinuria or haematuria) and eGFR is only slightly reduced (eGFR 60-90) then there is no CKD.

Management

• Conservative:
  • Lifestyle advice – exercise, good diet and weight control
  • Stop smoking
• Medical:
  • Optimise control of diabetes/hypertension and treat underlying causes
  • Treat complications:
    • Oral sodium bicarbonate for metabolic acidosis
    • Iron for Anaemia
    • Active vitamin D
  • Dialysis treatment
• Surgical:
  • Kidney Transplantation

Complications

• Metabolic acidosis (decreased H+ excretion & HCO3- reabsorption)
• Hyperkalaemia (↓ K loss from nephron), anaemia (decreased EPO)
• Renal bone disease (low calcitriol & secondary hyperparathyroidism)
• Hypertension (fluid overload)
• Peripheral neuropathy (electrolytes imbalance)