From the Guidelines
An eGFR of less than 60 mL/min/1.73m² denotes acute kidney injury (AKI) in the context of a decrease in kidney function over a short period of time, as defined by the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines 1.
Definition of AKI
The KDIGO guidelines define AKI as an increase in serum creatinine by 0.3 mg/dL within 48 hours, an increase in serum creatinine to 1.5 times baseline within 7 days, or urine output less than 0.5 mL/kg/h for 6 hours 1.
eGFR as a Key Indicator
eGFR is a crucial indicator for detecting AKI, as it provides a more accurate assessment of kidney function compared to serum creatinine alone 1.
Normal eGFR Values
Normal eGFR values are typically above 90 mL/min/1.73m², while values below 60 mL/min/1.73m² suggest kidney dysfunction 1.
Importance of eGFR Trends
When monitoring for AKI, it's essential to track eGFR trends rather than isolated values, as the rate and magnitude of decline provide crucial diagnostic information 1.
Calculation of eGFR
eGFR is calculated using formulas that incorporate serum creatinine levels, age, sex, race, and sometimes weight, making it a more accurate measure of kidney function than creatinine alone 1.
Early Detection and Intervention
Early detection of eGFR decline allows for prompt intervention to prevent further kidney damage, highlighting the importance of regular monitoring and timely intervention in patients at risk of AKI 1. Some key points to consider when evaluating eGFR and AKI include:
- The KDIGO guidelines provide a standardized definition of AKI based on serum creatinine and urine output criteria 1
- eGFR is a valuable tool for assessing kidney function and detecting AKI, but it should be interpreted in the context of the patient's overall clinical presentation 1
- Regular monitoring of eGFR trends is essential for early detection and intervention in patients at risk of AKI 1
From the Research
Definition of Acute Kidney Injury (AKI)
- Acute kidney injury (AKI) is defined as an increase in serum creatinine levels by at least 0.3 mg/dl within 48 hours or 1.5-fold the baseline, which is known or presumed to have occurred within the preceding 7 days, or a urine volume less than 0.5 ml/kg/hour for at least 6 hours 2, 3.
- The Kidney Disease: Improving Global Outcomes (KDIGO) group established consensus definitions for AKI, which are based on serum creatinine level increase and/or urine output decrease 2.
eGFR and AKI
- Estimated glomerular filtration rate (eGFR) is a measure of kidney function, but there is no direct evidence in the provided studies that links a specific eGFR value to AKI 4.
- However, studies suggest that AKI is associated with increased risks of incidence or progression of chronic kidney disease (CKD), kidney failure (KF), or major adverse kidney events (MAKE) 5.
Risk Factors for AKI
- Systemic illness or toxic exposure can cause AKI, and determining the cause is critical when possible 3.
- Nephrotoxic drugs, such as aminoglycosides, can increase the risk of AKI, especially in patients with low albumin or low hemoglobin levels 6.
- Other risk factors for AKI include diabetes mellitus, hypertension, requiring acute dialysis, cardiovascular surgery, or coronary artery disease 5.
Diagnosis and Management of AKI
- Urinalysis with microscopy can narrow the differential diagnosis of AKI, and management includes control of the underlying cause, achievement and maintenance of euvolemia, nutritional optimization, blood glucose control, and pharmacotherapy 3.
- Emergent referral to a nephrology subspecialist is recommended for patients with stage 2 or 3 AKI, or if the etiology of the AKI is unclear 3.