Your kidneys are vital organs, playing a crucial role in maintaining your overall health. Situated on either side of your spine, near your waist, these bean-shaped powerhouses work tirelessly to filter your blood, removing waste and excess fluid. This filtration process is carried out by tiny units within the kidneys called glomeruli. A Glomerular Filtration Rate (GFR) test, a simple blood test, is used to assess just how effectively these glomeruli are performing their critical task.
When kidneys are compromised by conditions like kidney disease, their filtering efficiency decreases. The GFR test directly measures how much blood your kidneys filter every minute, providing a clear indication of their functionality. While a direct GFR measurement is complex, healthcare providers typically estimate GFR, referred to as eGFR, using readily available blood tests.
The most common method to calculate eGFR involves measuring creatinine levels in your blood. Creatinine is a waste product generated from the normal breakdown of muscle tissue. Healthy kidneys efficiently remove creatinine from the blood, but when kidney function is impaired, creatinine levels can rise. To get a comprehensive eGFR, healthcare professionals use your creatinine level along with other personal factors such as:
- Age
- Gender
- Weight
- Height
- Race or ethnicity
These factors are incorporated into a GFR calculator, a mathematical formula, to accurately estimate your eGFR.
In some instances, eGFR might also be calculated using cystatin C levels in the blood. Cystatin C is a protein produced by various cells in the body. Unlike creatinine, cystatin C levels are less influenced by muscle mass, diet, or age. Consequently, some researchers believe cystatin C offers a more precise GFR estimation than creatinine alone. In specific situations, both creatinine and cystatin C levels are used in conjunction to calculate eGFR in adults, providing a more robust assessment of kidney function.
Understanding your GFR is a key step in monitoring your kidney health. This valuable metric helps healthcare providers detect kidney disease early, allowing for timely interventions and management strategies to preserve kidney function and overall well-being.
Other terms you might encounter for a GFR test include estimated GFR, eGFR, calculated glomerular filtration rate, and cGFR.
