Stages of Uremia: Understanding Kidney Failure Progression and Global Classification Standards
Chronic kidney failure, particularly when progressing to uremia, is a serious medical condition that affects millions worldwide. In the past, staging was primarily based on serum creatinine levels, which reflect how well the kidneys are filtering waste from the blood. According to earlier classification systems used in certain regions, chronic renal failure is divided into four stages based on creatinine concentration.
Traditional Staging Based on Serum Creatinine Levels
Stage 1: Compensated Chronic Kidney Failure
Serum creatinine levels below 178 μmol/L indicate the compensated stage of chronic kidney disease (CKD). At this point, the kidneys are still able to maintain essential functions despite underlying damage. Patients may remain asymptomatic, but early detection through routine blood tests can help slow progression with lifestyle changes and proper management.
Stage 2: Decompensated Chronic Kidney Failure (Azotemia Phase)
When creatinine rises to between 178 and 442 μmol/L, the condition enters the decompensated phase, also known as azotemia. This means waste products like urea and creatinine begin accumulating in the bloodstream. Symptoms such as fatigue, nausea, and fluid retention may start appearing, signaling reduced kidney efficiency.
Stage 3: Renal Failure Stage
At creatinine levels between 442 and 707 μmol/L, the kidneys are significantly impaired. This stage reflects advanced renal failure where patients often experience more pronounced symptoms including anemia, high blood pressure, and electrolyte imbalances. Medical intervention becomes critical to manage complications and prepare for potential long-term treatment options.
Stage 4: Uremic Stage
When serum creatinine exceeds 707 μmol/L, it marks the onset of the uremic stage. This severe level indicates near-total loss of kidney function. Without timely intervention, toxic buildup can lead to life-threatening conditions affecting the heart, brain, and other vital organs.
Modern Global Classification Using eGFR
Today, international guidelines emphasize a more accurate and personalized method of assessing kidney health—estimated Glomerular Filtration Rate (eGFR). Unlike creatinine alone, eGFR takes into account age, sex, body size, and race, offering a clearer picture of actual kidney performance.
The Five-Stage CKD Classification by eGFR
Kidney function is now categorized into five stages based on eGFR values:
- Stage 1: eGFR ≥ 90 – Normal or high filtration with evidence of kidney damage
- Stage 2: eGFR 60–89 – Mild decline in function
- Stage 3a & 3b: eGFR 45–59 (moderate) and 30–44 (moderately severe)
- Stage 4: eGFR 15–29 – Severe reduction requiring specialist care and planning for replacement therapy
- Stage 5: eGFR < 15 – Defined as end-stage renal disease (ESRD) or uremia
Managing Stage 5: Preparing for Kidney Replacement Therapy
Once eGFR drops below 15 mL/min/1.73m², patients are diagnosed with uremic-stage kidney failure. At this point, kidney replacement therapies become necessary. Options include:
- Hemodialysis: Blood is filtered through a machine outside the body, typically performed at a clinic three times per week.
- Peritoneal Dialysis: A home-based treatment using the lining of the abdomen to filter waste and excess fluids.
- Kidney Transplantation: The most effective long-term solution, offering improved quality of life and survival rates compared to dialysis.
Early diagnosis, regular monitoring, and proactive management are key to slowing disease progression and improving outcomes. Awareness of both traditional markers like creatinine and modern tools like eGFR empowers patients and healthcare providers to make informed decisions about treatment and lifestyle adjustments.