From the Guidelines
The 2021 CKD-EPI equation is a reliable method for estimating GFR in patients with a serum creatinine level of 1.15 mg/dL, as it eliminates the race coefficient and provides a more equitable estimate across populations. This equation is recommended by the American Society of Nephrology and National Kidney Foundation, as stated in the 2022 study by the American Diabetes Association (ADA) and Kidney Disease: Improving Global Outcomes (KDIGO) 1. The 2021 CKD-EPI equation calculates eGFR without regard to race, using serum creatinine, age, and sex, making it a valuable tool for screening and diagnosis of chronic kidney disease (CKD).
For a patient with a serum creatinine level of 1.15 mg/dL, the accuracy of the 2021 CKD-EPI equation depends on several patient factors, including age, sex, and whether the creatinine level represents a stable baseline. The equation performs best in patients with moderate kidney dysfunction and may be less accurate at very high or very low GFR values. A serum creatinine of 1.15 mg/dL might indicate normal kidney function in a muscular male but could represent mild kidney impairment in a smaller female.
The reliability of the 2021 CKD-EPI equation is enhanced when combined with clinical context and other markers of kidney function, such as urine albumin-to-creatinine ratio (ACR) 1. The equation works by accounting for the relationship between creatinine production (which varies by muscle mass) and kidney filtration, providing a standardized estimate that helps clinicians assess kidney function without invasive testing. According to the 2017 study by the American Society of Clinical Oncology, CKD-EPI is more accurate with GFR > 60 mL/min/1.73 m2 and is a better predictor of adverse outcomes (ESRD and mortality) compared with MDRD 1.
Key considerations when using the 2021 CKD-EPI equation include:
- Patient age and sex
- Serum creatinine level and its stability
- Presence of other markers of kidney function, such as ACR
- Clinical context, including presence of comorbidities and muscle mass
- Potential limitations of the equation, including reduced accuracy at very high or very low GFR values.
Overall, the 2021 CKD-EPI equation is a reliable and valuable tool for estimating GFR in patients with a serum creatinine level of 1.15 mg/dL, and its use is recommended in clinical practice, as supported by the 2022 ADA and KDIGO study 1.
From the Research
Estimating GFR using the 2021 CKD-EPI Equation
The 2021 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation is a creatinine-based method for estimating glomerular filtration rate (GFR) in routine practice 2. This equation is considered the most accurate method for estimating GFR.
Reliability of the 2021 CKD-EPI Equation
The reliability of the 2021 CKD-EPI equation in estimating GFR is supported by several studies. One study found that the equation is accurate for estimating GFR in patients with chronic kidney disease (CKD) 3. Another study found that the equation is reliable for identifying CKD and its progression 4.
Limitations of the 2021 CKD-EPI Equation
However, the equation has some limitations. It may not be accurate in patients with extreme ages, high or low muscle mass, or those with certain ethnic backgrounds 5. Additionally, the equation may not be reliable for estimating GFR in patients with very high or very low GFR values 6.
Application of the 2021 CKD-EPI Equation
In the case of a patient with a serum creatinine level of 1.15, the 2021 CKD-EPI equation can be used to estimate GFR. However, it is essential to consider the patient's age, sex, and ethnicity when using the equation, as these factors can affect the accuracy of the estimate 2, 6.
Key Points to Consider
- The 2021 CKD-EPI equation is a reliable method for estimating GFR in patients with CKD.
- The equation has limitations, including potential inaccuracy in patients with extreme ages, high or low muscle mass, or certain ethnic backgrounds.
- The equation should be used in conjunction with other clinical factors, such as patient history and physical examination, to diagnose and manage CKD.
- Cystatin C level measurement can be considered if patients have factors that might make creatinine-based equations inaccurate 2.