Understanding the Two Key Markers
1. Estimated Glomerular Filtration Rate (eGFR)
eGFR estimates how effectively the kidneys filter waste from the blood. It is calculated using serum creatinine and a validated equation. A persistently reduced eGFR may indicate impaired kidney function, even before symptoms develop.
An eGFR below 60 mL/min/1.73 m², sustained for at least three months, is a marker of CKD. However, an eGFR of 60 or above does not exclude CKD if other markers of kidney damage are present.
2. Urine Albumin-to-Creatinine Ratio (uACR)
The uACR measures albumin in the urine relative to creatinine. Healthy kidneys generally retain albumin in the bloodstream, so elevated urinary albumin may indicate kidney damage.
The uACR is classified into three categories:
A1: Less than 30 mg/g — normal to mildly increased.
A2: 30–300 mg/g — moderately increased.
A3: Greater than 300 mg/g — severely increased.
Elevated uACR can indicate kidney damage even when eGFR remains within the normal or near-normal range.
Why Both Tests Matter
eGFR and uACR provide complementary information. While eGFR reflects filtration function, uACR helps identify kidney damage and provides additional insight into the risk of disease progression.
For example, a patient with diabetes may have an eGFR of 85 mL/min/1.73 m² but a uACR of 150 mg/g. Although filtration appears relatively preserved, the elevated albumin level may indicate CKD if the abnormality persists for at least three months.
Conversely, a patient with a reduced eGFR and normal uACR may still have CKD and requires further assessment. Considering both markers enables more accurate risk classification and supports individualised clinical management.
Clinical Implications for Healthcare Professionals
The KDIGO 2024 guideline recommends assessing both GFR and albuminuria in individuals at risk of CKD. Abnormal findings should be interpreted in the context of clinical history and confirmed when appropriate, as temporary changes may occur due to factors such as acute illness, urinary tract infection or strenuous exercise.
For patients with established CKD, monitoring frequency should reflect disease severity and the risk of progression. Management may include blood pressure and glycaemic control, cardiovascular risk reduction, medication review and evidence-based kidney-protective therapies when indicated.
Key takeaway: eGFR alone does not provide a complete picture of kidney health. Combining eGFR with uACR helps clinicians detect CKD earlier, stratify risk more accurately and guide appropriate monitoring and management.
Disclaimer: For healthcare professional education. This content does not replace individual clinical assessment or applicable local guidelines.