Chronic Kidney Disease (CKD): Stages, Complications and Treatment

Chronic kidney disease (CKD) is long-term damage to the kidneys or reduced kidney function lasting more than 3 months. It is very common, usually silent until advanced, and strongly linked to diabetes, hypertension and cardiovascular disease. Early detection and treatment slow its progression.

Definition and staging (KDIGO)

CKD means abnormal kidney structure or function for more than 3 months. This is shown either by:

• an eGFR below 60 mL/min/1.73 m², or
• markers of kidney damage, such as albuminuria, blood in the urine of kidney origin, or structural abnormalities.

CKD is staged by GFR (G) and albuminuria (A).

GFR stages (mL/min/1.73 m²):

• G1: 90 or more.
• G2: 60–89.
• G3a: 45–59.
• G3b: 30–44.
• G4: 15–29.
• G5: below 15 (kidney failure).

Albuminuria stages (urine albumin:creatinine ratio, ACR):

• A1: below 3 mg/mmol.
• A2: 3–30 mg/mmol.
• A3: above 30 mg/mmol.

Higher stages of either mean greater risk of progression and cardiovascular events.

Causes

• Diabetes (diabetic kidney disease) — the leading cause.
• Hypertension.
• Glomerulonephritis.
• Polycystic kidney disease.
• Chronic obstruction (for example stones or an enlarged prostate).
• Recurrent infection and reflux.
• Drugs (long-term NSAIDs, lithium).
• Kidney stones.

Clinical features

Early CKD usually causes no symptoms. Advanced CKD can cause:

• tiredness
• itching
• loss of appetite
• nausea
• swelling
• breathlessness
• restless legs
• muscle cramps
• passing less urine or more at night

Complications

• Cardiovascular disease — the main cause of death in CKD.
• Anaemia — reduced erythropoietin and iron deficiency.
• CKD–mineral and bone disorder:
  • high phosphate
  • low calcium
  • raised parathyroid hormone (secondary hyperparathyroidism)
  • vitamin D deficiency
• Metabolic acidosis.
• Hyperkalaemia.
• Fluid overload and hypertension.
• Uraemia in kidney failure.

Management

• Control blood pressure to target. Use an ACE inhibitor or ARB in patients with significant albuminuria, monitoring potassium and creatinine.
• SGLT2 inhibitors (for example dapagliflozin, empagliflozin) slow progression in many patients with CKD, with or without diabetes.
• Good glucose control in diabetes. Some patients also benefit from finerenone or GLP-1 receptor agonists, under specialist guidance.
• Statins for cardiovascular risk reduction.
• Avoid nephrotoxins (NSAIDs) and adjust drug doses.
• Treat complications:
  • iron and erythropoiesis-stimulating agents for anaemia
  • phosphate control and vitamin D
  • bicarbonate for acidosis
  • dietary advice
• Vaccination, including hepatitis B before dialysis.
• Plan early for kidney failure:
  • education
  • an arteriovenous fistula for haemodialysis
  • peritoneal dialysis
  • transplantation
  • conservative care

Exam pearls

• Screen people with diabetes and hypertension annually with eGFR and urine ACR.
• A rise in creatinine of up to about 30% after starting an ACE inhibitor or ARB can be acceptable; a larger rise needs review.
• Small kidneys on ultrasound suggest chronic disease. Normal-sized kidneys can be seen in diabetes, amyloidosis and polycystic kidney disease.

See also Acute Kidney Injury, Type 2 Diabetes, Hypertension and our Medicine Companion.

Test yourself

5 exam-style single-best-answer questions. Choose your answer, then tap “Show answer”.

1. eGFR 38 for 6 months. CKD stage?

   1. G5
   2. G2
   3. G3b
   4. G4
   5. G3a
   Show answer

   Answer: C. G3b
   G3b is eGFR 30–44.

2. Most common cause of CKD:

   1. Kidney stones
   2. Diabetes
   3. Lupus
   4. Polycystic kidney disease
   5. Lithium
   Show answer

   Answer: B. Diabetes
   Diabetic kidney disease is the leading cause, followed by hypertension.

3. Which drug class slows CKD progression in many patients with or without diabetes?

   1. Loop diuretics
   2. Sulfonylureas
   3. SGLT2 inhibitors
   4. NSAIDs
   5. Thiazolidinediones
   Show answer

   Answer: C. SGLT2 inhibitors
   SGLT2 inhibitors reduce progression of CKD and cardiovascular events.

4. Anaemia in CKD is mainly due to:

   1. B12 deficiency
   2. Bone marrow cancer
   3. Bleeding only
   4. Reduced erythropoietin production
   5. Haemolysis
   Show answer

   Answer: D. Reduced erythropoietin production
   Reduced renal erythropoietin, plus iron deficiency, causes anaemia of CKD.

5. Leading cause of death in CKD:

   1. Cancer
   2. Hyperkalaemia
   3. Uraemia
   4. Infection
   5. Cardiovascular disease
   Show answer

   Answer: E. Cardiovascular disease
   Cardiovascular disease is the main cause of death in CKD.

More articles in Nephrology & Urology

• Acute Kidney Injury (AKI): KDIGO Criteria and ManagementAKI definition and staging, pre-renal, renal and post-renal causes, assessment, stopping nephrotoxins, hyperkalaemia and dialysis indications.
• Kidney Stones and Renal Colic: Diagnosis and TreatmentTypes of stones, risk factors, renal colic, CT KUB, pain relief, which stones pass, ESWL, ureteroscopy, emergency drainage and prevention.

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Disclaimer

For education and exam preparation only. This is not medical advice and must not be used to diagnose or treat patients. Always follow current clinical guidelines and the advice of qualified senior colleagues.