Chronic Kidney Disease (CKD), which can lead to renal failure if untreated, is often diagnosed through simple blood and urine tests. Many individuals discover they have CKD during routine check-ups for other health concerns, where these tests reveal abnormalities in kidney function.
Who Needs Renal Function Testing?
Consulting a doctor is crucial if you experience persistent symptoms that might indicate kidney problems. These symptoms include:
- Unexplained weight loss or loss of appetite
- Swelling in ankles, feet, or hands (oedema)
- Shortness of breath
- Persistent fatigue
- Blood in urine
- Increased urination, especially at night
While these symptoms can point to CKD and potentially lead to renal failure, it’s important to note that early stages of kidney disease often present no noticeable symptoms. Therefore, regular testing is recommended for individuals at higher risk.
Regular renal function testing is advised if you have:
- Diabetes: High blood sugar levels can damage kidneys over time.
- High blood pressure (hypertension): Elevated blood pressure puts strain on the kidneys.
- A family history of kidney disease: Genetic predisposition increases risk.
Alt: A vial of blood being prepared for a kidney function blood test, highlighting the initial step in renal failure diagnosis.
Children and young adults with only one functioning kidney should also undergo regular testing. Furthermore, individuals of Black or South Asian descent have a higher likelihood of developing kidney disease.
Those on long-term medications that can impact kidney health, such as lithium, omeprazole, or non-steroidal anti-inflammatory drugs (NSAIDs), should also be regularly monitored. Discuss with your doctor if you believe you might benefit from regular kidney function testing.
Key Tests for Diagnosing Renal Failure
Blood Tests for Kidney Function
The primary test for assessing kidney function is a blood test. This test measures creatinine levels, a waste product in your blood. Based on your creatinine levels, age, body size, and gender, doctors calculate your estimated glomerular filtration rate (eGFR). eGFR indicates the volume of waste your kidneys can filter per minute.
A healthy eGFR is typically 90ml/min or higher. An eGFR below this level may suggest CKD and potential progression towards renal failure.
Urine Tests for Kidney Health
A urine test is also essential for a comprehensive Renal Failure Diagnosis. It serves to:
- Determine the albumin:creatinine ratio (ACR), which measures albumin and creatinine levels in your urine.
- Detect the presence of blood or protein in the urine, both indicators of kidney issues.
Alt: A person holding a urine sample container, illustrating the process of urine collection for renal function testing to aid in renal failure diagnosis.
Combined with eGFR, urine tests provide a more complete picture of kidney function and help in diagnosing renal failure.
Additional Diagnostic Tests
In some instances, further tests are necessary to evaluate the extent of kidney damage. These might include imaging tests like ultrasounds or CT scans to visualize the kidneys’ structure and identify any abnormalities. Kidney biopsies, where a small tissue sample is taken for examination, are less common but can provide detailed information about kidney health.
Understanding Your Test Results and Stages of CKD
Test results are crucial in determining the stage of CKD, reflecting the degree of kidney damage. This staging guides treatment decisions and the frequency of monitoring.
Your eGFR result is categorized into five stages:
- Stage 1 (G1): eGFR above 90ml/min (normal), but other tests indicate kidney damage.
- Stage 2 (G2): eGFR 60-89ml/min (mildly reduced), with other signs of kidney damage.
- Stage 3a (G3a): eGFR 45-59ml/min (moderately reduced).
- Stage 3b (G3b): eGFR 30-44ml/min (moderately reduced).
- Stage 4 (G4): eGFR 15-29ml/min (severely reduced).
- Stage 5 (G5): eGFR below 15ml/min (kidney failure), indicating near complete loss of kidney function.
Your ACR result is staged from A1 to A3:
- A1: ACR less than 3mg/mmol (normal to mildly increased albuminuria).
- A2: ACR 3-30mg/mmol (moderately increased albuminuria).
- A3: ACR greater than 30mg/mmol (severely increased albuminuria).
Higher stages for both eGFR and ACR signify more advanced kidney disease and a greater risk of renal failure. Understanding these tests and results is the first step in managing kidney health and preventing renal failure.
