What is chronic kidney disease?
Chronic kidney disease (CKD) means your kidneys are not filtering waste from the blood as efficiently as they should — and this has been going on for at least 3 months. The kidneys filter about 200 litres of blood per day. When they fail to do this job, waste products, extra fluid and certain minerals build up to dangerous levels. CKD affects about 10% of the global population and is a leading cause of death worldwide.
The 5 stages of CKD — based on eGFR
| Stage | eGFR (mL/min/1.73m²) | Kidney Function | What it means |
|---|---|---|---|
| Stage 1 | ≥ 90 | Normal or high | Kidney damage with normal function |
| Stage 2 | 60 – 89 | Mildly reduced | Mild decline — monitor closely |
| Stage 3a | 45 – 59 | Mildly-moderately reduced | Moderate decline |
| Stage 3b | 30 – 44 | Moderately-severely reduced | Specialist referral needed |
| Stage 4 | 15 – 29 | Severely reduced | Prepare for dialysis planning |
| Stage 5 | < 15 | Kidney failure | Dialysis or transplant required |
Key kidney blood test results
| Test | Normal Range | What it means when raised |
|---|---|---|
| Creatinine (men) | 0.74–1.35 mg/dL | Kidneys not filtering waste properly |
| Creatinine (women) | 0.59–1.04 mg/dL | Kidneys not filtering waste properly |
| BUN (Blood Urea Nitrogen) | 7–20 mg/dL | Kidney impairment or dehydration |
| eGFR | > 60 mL/min/1.73m² | Below 60 = possible CKD |
| Uric acid (men) | 3.5–7.2 mg/dL | Gout risk, kidney stone risk |
| Potassium | 3.5–5.0 mEq/L | High K+ = kidney can't excrete — heart risk |
| Urine protein | Negative / <150 mg/day | Protein in urine = kidney filter leaking |
What causes kidney disease?
The two most common causes of CKD worldwide are diabetes (diabetic nephropathy) and high blood pressure (hypertensive nephropathy). Together, they account for about 60–70% of all CKD cases. Other causes include:
- Glomerulonephritis — inflammation of the kidney filtering units
- Polycystic kidney disease (genetic)
- Repeated urinary tract infections
- Kidney stones causing obstruction
- Long-term use of NSAIDs (ibuprofen, naproxen) or certain antibiotics
- Lupus and other autoimmune conditions
Symptoms of kidney disease
CKD is often called a "silent disease" because early stages have no symptoms. Later stages cause:
- Swelling in the feet, ankles and legs (fluid retention)
- Puffy face — especially around the eyes in the morning
- Fatigue and weakness (anaemia from low EPO production)
- Decreased urine output or foamy urine (proteinuria)
- Itchy skin (uraemic pruritis)
- Nausea, loss of appetite, metallic taste in the mouth
- Shortness of breath (fluid in lungs)
- High blood pressure that's difficult to control
How to slow down kidney disease progression
- Control blood sugar: Keep HbA1c below 7% in diabetes
- Control blood pressure: Target below 130/80 mmHg — ACE inhibitors and ARBs protect the kidneys
- Low-protein diet: May slow progression in advanced CKD — discuss with your nephrologist
- Avoid nephrotoxic drugs: NSAIDs, contrast dye, aminoglycoside antibiotics
- Stay hydrated: Drink adequate water unless told otherwise by your doctor
- Quit smoking: Smoking accelerates CKD progression
Questions to ask your doctor
- What stage is my kidney disease?
- How quickly has my eGFR been declining?
- Do I need to see a kidney specialist (nephrologist)?
- Should I restrict protein or potassium in my diet?
- Which of my current medications might be hard on my kidneys?
Medical Disclaimer: This page is for general educational purposes only and does not constitute medical advice. Always consult a qualified doctor for diagnosis and treatment decisions.