The kidneys filter waste products and excess fluid from the blood, playing a central role in overall health. Glomerular Filtration Rate (GFR) indicates how effectively these vital organs perform their filtering function. Understanding GFR is important as individuals age, as it helps healthcare providers assess kidney health and identify potential concerns.
What GFR Measures
GFR quantifies the efficiency of the kidneys’ filtering units, known as glomeruli. This rate is typically estimated (eGFR) using a simple blood test that measures creatinine levels, a waste product from muscle metabolism. The eGFR calculation incorporates factors such as age, sex, and sometimes height and weight, to provide a personalized estimate of kidney performance. While creatinine is the primary marker, some calculations may also use cystatin C, another protein, which is thought to be less influenced by muscle mass or diet. GFR is commonly reported in milliliters per minute (mL/min), reflecting the volume of blood filtered per minute.
GFR Ranges for Older Adults
GFR naturally declines with age, even in healthy individuals. A GFR value will typically be lower than that of younger adults. An average estimated GFR for individuals aged 70 and over is around 75 mL/min, with some sources suggesting a range of 70-75 mL/min or potentially lower. A GFR above 60 mL/min is generally considered good kidney function for adults. However, for someone around 70, a GFR slightly below 60 mL/min might still be acceptable depending on their overall health. The context of age is crucial for interpreting GFR results, as an age-related decline does not always signify disease.
Factors Influencing GFR Readings
Beyond natural aging, several factors can influence GFR readings, including chronic conditions like diabetes and high blood pressure, which are leading causes of kidney damage. Certain medications (NSAIDs, some antibiotics), dehydration, acute illnesses, and dietary habits can also temporarily alter GFR. For instance, a very high protein diet or significant changes in muscle mass can influence creatinine levels. Less common factors like pregnancy, liver cirrhosis, or nephrotic syndrome may also affect GFR estimation accuracy. Healthcare providers consider these variables when interpreting a GFR result.
Understanding Your GFR Results
GFR numbers indicate varying levels of kidney function. A GFR consistently below 60 mL/min for three months or more often suggests chronic kidney disease (CKD). CKD is categorized into stages based on GFR levels to guide treatment and monitoring, with stages ranging from GFR of 90 mL/min or higher (Stage 1 with damage) to 30-59 mL/min (Stage 3). A GFR below 15 mL/min indicates kidney failure, requiring interventions like dialysis or a kidney transplant. A single GFR reading is not always definitive; a healthcare provider considers overall health, medical history, and other tests, such as urine protein levels, to get a complete picture, and should be consulted if results are outside the expected range or show a significant decline for accurate diagnosis and guidance.
Supporting Kidney Health with Age
Maintaining kidney health with age involves several proactive measures. Staying adequately hydrated is important, as water helps the kidneys filter waste and toxins efficiently. Managing underlying health conditions like diabetes and high blood pressure is crucial, as these are primary drivers of kidney damage. Adopting a kidney-friendly diet, characterized by low sodium and moderate protein, can lessen the burden on the kidneys. Regular physical activity, avoiding smoking, and limiting alcohol intake promote kidney well-being, while regular medical check-ups and open discussions with a doctor about all medications are essential for monitoring and protecting kidney health.