Estimated Glomerular Filtration Rate (eGFR)

Overview

The estimated glomerular filtration rate (eGFR) is a critical measure used to assess kidney function by estimating the volume of blood filtered by the kidneys over time^[2]. It plays a vital role in diagnosing and managing kidney diseases. eGFR is calculated using serum creatinine levels, age, sex, and sometimes race^[2]. Tracking eGFR helps monitor kidney health and detect potential kidney problems early.

Scientific Background

eGFR reflects the kidneys" ability to filter waste products from the blood. Creatinine, a byproduct of muscle metabolism, is used as a marker because it is primarily cleared by the kidneys^[2]. The most commonly used equations for calculating eGFR include the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equations, which incorporate serum creatinine and cystatin C levels^[1]. These equations help standardize kidney function assessment across different populations.

Measurement and Testing

eGFR is typically measured through a blood test that assesses serum creatinine or cystatin C levels. The CKD-EPI equations are widely recommended for calculating eGFR due to their accuracy^[3]. Factors such as muscle mass, age, and ethnicity can affect eGFR results, so adjustments may be necessary in certain populations^[2].

Reference Ranges

A normal eGFR is generally considered to be 90 mL/min/1.73 m² or higher. However, values can vary based on age, sex, and ethnicity. For example, individuals of African-Caribbean descent may require an adjustment factor in some calculations^[2]. eGFR values are categorized into stages of chronic kidney disease (CKD), with lower values indicating more severe kidney impairment.

High Values

High eGFR values are less common and may not typically indicate a health risk. However, they can occur in individuals with high muscle mass or those who have recently received intravenous contrast agents^[2]. In some cases, high eGFR might not accurately reflect kidney function if there are other factors affecting creatinine levels.

Low Values

Low eGFR values indicate impaired kidney function and are associated with chronic kidney disease (CKD). Causes include diabetes, hypertension, and kidney damage. Low eGFR can lead to symptoms like fatigue, swelling, and electrolyte imbalances^[2].

Improving Biomarker Levels

Improving eGFR involves managing underlying conditions like diabetes and hypertension through lifestyle changes and medical interventions. Maintaining a healthy diet, exercising regularly, and avoiding nephrotoxic substances can help preserve kidney function^[2]. While supplements are not typically recommended for improving eGFR, certain nutrients like omega-3 fatty acids may support overall kidney health.

Importance of Tracking

Tracking eGFR is crucial for early detection and management of kidney diseases. Regular monitoring helps healthcare providers assess the effectiveness of treatments and make informed decisions about patient care^[3]. It also allows for timely interventions to prevent progression to more severe kidney disease.

Disclaimer

The information provided in this document is for educational purposes only and does not constitute medical advice. It is essential to consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.