When you receive blood test results, you might see the acronym GFR. This measurement is an important indicator of kidney function, showing how effectively these organs filter waste from your blood. Understanding your GFR score helps healthcare providers assess kidney health and detect potential issues early.
What GFR Means
GFR stands for Glomerular Filtration Rate. It measures how efficiently your kidneys filter waste products and excess fluid from your blood. Each kidney contains millions of tiny filtering units called nephrons, which include structures known as glomeruli.
These glomeruli are networks of small blood vessels that act as sieves. As blood flows through them, they allow waste and water to pass into collecting tubules, while retaining beneficial components like proteins and blood cells. GFR quantifies the amount of blood these filters clean each minute.
Interpreting Your GFR Score
Your GFR is typically reported as an estimated value, known as eGFR. This value is calculated using a formula that considers factors from your blood test, including creatinine levels, age, and sex. Some calculations may also incorporate cystatin C levels for a more accurate estimate.
For healthy adults, a normal eGFR is usually 90 milliliters per minute per 1.73 square meters (mL/min/1.73 m²) or higher. eGFR naturally declines with age.
Different eGFR ranges indicate various stages of chronic kidney disease (CKD). An eGFR between 60 and 89 mL/min/1.73 m² may suggest mild kidney damage. A score between 30 and 59 mL/min/1.73 m² indicates moderate kidney function loss, often categorized as Stage 3 CKD.
Severe loss of kidney function is indicated by an eGFR between 15 and 29 mL/min/1.73 m² (Stage 4). An eGFR below 15 mL/min/1.73 m² signifies kidney failure (Stage 5). A diagnosis of chronic kidney disease is typically made if an eGFR remains below 60 mL/min/1.73 m² for three months or longer.
Influencing Factors and Medical Advice
Various factors can influence GFR results. Age is a significant consideration, as eGFR naturally decreases over time. Hydration levels also play a role; dehydration can lead to a temporary decrease in GFR. Certain medications, such as non-steroidal anti-inflammatory drugs (NSAIDs), some antibiotics, and specific diabetes medications, can affect kidney function and GFR.
Underlying health conditions like diabetes and high blood pressure are common contributors to GFR changes. Diabetes can damage the tiny blood vessels in the kidneys, impairing their filtering ability, while uncontrolled high blood pressure can also harm kidney structures.
Other influencing factors include muscle mass, diet, and chronic illnesses. It is important to discuss your GFR results with a healthcare professional for personalized guidance. A single abnormal reading does not always indicate permanent kidney damage, and further tests may be necessary to understand your full kidney health.