From the Guidelines
A Glomerular Filtration Rate (GFR) of 64 mL/min/1.73m² is considered to be slightly below the normal range, indicating a potential decline in kidney function, but not necessarily a significant loss of kidney function. According to the guidelines from the National Kidney Foundation, a normal GFR varies according to age, sex, and body size, with a normal GFR in young adults being approximately 120 to 130 mL/min per 1.73 m², and declining with age 1.
Key Points to Consider
- A GFR level less than 60 mL/min per 1.73 m² represents a loss of half or more of the adult level of normal kidney function, and below this level, the prevalence of complications of chronic kidney disease increases 1.
- The age-related decline in GFR has been considered part of normal aging, but decreased GFR in the elderly is an independent predictor of adverse outcomes, such as death and cardiovascular disease (CVD) 1.
- The definition of chronic kidney disease is the same, regardless of age, and a GFR of 64 mL/min/1.73m² may indicate early stages of kidney disease, requiring regular medical supervision and potential lifestyle modifications.
Recommendations
- Regular kidney function tests every 6-12 months to monitor the progression of kidney disease.
- Blood pressure control, aiming for readings below 130/80 mmHg, using medications like ACE inhibitors or ARBs if prescribed.
- Dietary modifications, including moderate protein intake, reduced sodium, and potassium restrictions if levels are elevated.
- Avoidance of nephrotoxic medications like NSAIDs when possible.
Conclusion Not Applicable, Further Action Required
It is essential to consult with a healthcare professional to determine the best course of action and to monitor kidney function regularly, as a GFR of 64 mL/min/1.73m² may indicate a need for lifestyle modifications and potential medical interventions to slow the progression of kidney disease 1.
From the Research
Kidney Function and GFR
- A Glomerular Filtration Rate (GFR) of 64 indicates that the kidney function is near the lower limit of what is considered normal for some individuals, particularly those under the age of 70 2.
- According to the K-DIGO guidelines, a fixed cut-off value of 60 mL/min/1.73 m2 is used to define normal kidney function, but this value does not take into account the physiological decrease in GFR with age 2.
- For adults older than 70 years, values below 60 mL/min/1.73 m2 could be considered normal due to the natural decline in kidney function with age 2.
Factors Influencing GFR Interpretation
- GFR values are influenced by various factors such as age, sex, muscle mass, and body composition, which can lead to misclassification of patients or inappropriate clinical decisions 3.
- The use of cystatin C as an alternative endogenous marker or direct measurement of GFR using an exogenous marker can provide more accurate assessments of kidney function in certain clinical scenarios 3.
Clinical Implications
- Accurate assessment of kidney function is crucial for managing conditions such as hypertension, heart failure, and chronic kidney disease, and for preventing disease progression 4, 5, 6.
- Angiotensin receptor blockers (ARBs) and angiotensin-converting enzyme inhibitors (ACEIs) are recommended as first-line therapy for hypertensive patients with chronic kidney disease and proteinuria, but their use may vary in clinical practice 6.