A glomerular filtration rate test evaluates the filtering efficiency of the kidneys through GFR/eGFR measurements. It is a core metric used to diagnose, stage, and monitor kidney health, particularly in high-risk individuals.
1. What is a Glomerular Filtration Rate Test?
GFR (Glomerular Filtration Rate) measures the volume of blood filtered by the tiny filters in the kidneys (glomeruli) per minute.
In routine clinical practice, directly measuring true GFR is complex. Therefore, doctors utilize eGFR (estimated Glomerular Filtration Rate). This parameter is calculated using equations based on blood biomarkers (such as Creatinine or Cystatin C) combined with the patient’s age and biological sex.
- Standard Unit of Measurement: eGFR is expressed as
mL/min/1.73 m².
2. Why is an eGFR Test Performed?
The eGFR parameter serves three vital functions in clinical evaluation:
- Screening Filtration Function: Detects early glomerular damage before obvious clinical symptoms appear.
- Staging Chronic Kidney Disease (CKD): Provides the standardized baseline for physicians to classify the severity of a patient’s kidney impairment.
- Monitoring Progression and Treatment: Comparing eGFR values across periodic checkups tracks the rate of renal decline, enabling timely adjustments to treatment plans or drug dosages.
3. How is Glomerular Filtration Rate Tested?
To calculate eGFR, patients only need a routine blood draw to measure key biomarkers:
- Serum Creatinine Test: Creatinine is a breakdown product of muscle metabolism measured in
mg/dL(orµmol/L). Serum creatinine is the most common input in standard eGFR calculation formulas. - Cystatin C Test: Cystatin C is a low-molecular-weight protein produced by nucleated cells at a constant rate, measured in
mg/L. Because it is independent of muscle mass and protein intake, Cystatin C serves as a valuable supplementary marker for older adults, patients with muscle atrophy, or specific physical conditions.
4. Understanding eGFR Stages and Reference Ranges
When reviewing your laboratory report, you can interpret your eGFR values (mL/min/1.73 m²) using the following medical guidelines:
- eGFR ≥ 90 (Normal / Stage G1): Good filtration function. In the absence of proteinuria or structural abnormalities on ultrasound, the kidneys are healthy.
- eGFR 60 – 89 (Mildly Decreased / Stage G2): Mild reduction in filtration. In older adults, this may reflect age-related physiological decline, but requires closer monitoring if underlying conditions like hypertension or diabetes are present.
- eGFR 30 – 59 (Moderately to Severely Decreased / Stage G3a – G3b): Noticeable decline in filtering capacity. If sustained for over 3 months, it indicates Chronic Kidney Disease (CKD).
- eGFR 15 – 29 (Severely Decreased / Stage G4): Severe impairment requiring specialized medical management and intervention.
- eGFR < 15 (End-Stage Kidney Failure / Stage G5): Near-complete loss of kidney function; renal replacement therapies (dialysis or kidney transplant) must be considered.
Note: eGFR values can fluctuate temporarily due to dehydration or certain medications. Physicians always evaluate overall trends across multiple tests rather than relying on a single reading.
5. Who Should Get Their eGFR Tested?
You should proactively schedule periodic eGFR testing if you fall into any of the following groups:
- Individuals with diabetes or high blood pressure (hypertension).
- People with a family history of kidney disease.
- Patients on long-term daily medications.
- Individuals with abnormal blood creatinine levels from previous checkups.
Accurate eGFR Evaluation at Pathlab
eGFR readings reflect true health status only when performed on standardized laboratory analyzers and interpreted by qualified physicians within your overall health context.
At Pathlab, we provide high-precision Creatinine and Cystatin C testing paired with expert medical consultations to help you take control of your renal health.
Book your kidney function checkup and eGFR test at Pathlab today starting from just 490,000 VND. Explore package details here!
