Estimated Glomerular Filtration Rate (eGFR)

eGFR is directly related to and calculated by creatinine. It represents your kidneys function by estimating how much blood your kidneys filter each minute. It is derived from a blood test and a formula that uses your serum creatinine, age, and sex, with modern equations designed to be accurate across populations without using race. Because eGFR reflects filtration rather than a single day’s hydration or diet, watching your personal pattern over time is a practical way to understand how everyday habits may be influencing kidney health

Your kidneys help clear wastes, balance fluids and minerals, and support hormones that affect blood pressure, bones, and energy. eGFR offers a simple, repeatable way to see how that filtration is tracking. A stable, higher eGFR generally indicates healthy kidney filtration for your body, while a lower or steadily falling eGFR suggests reduced capacity and deserves attention to long-term lifestyle patterns. If you have concerns about your eGFR or creatinine, you should seek medical attention from your primary care provider.

Think of eGFR as a “training log” for your kidneys. These steps help you optimise the signal and the number itself over the long haul:

• Standardise your test routine. For the 24 hours before your blood draw, avoid a large cooked-meat meal, skip unusually hard workouts, and test at a similar time of day. These simple tweaks reduce short-term dips in eGFR caused by temporary creatinine bumps.

• Use the most appropriate equation. Modern labs use the CKD-EPI 2021 race-free formula. If your body composition is unusual for your size, asking your provider about cystatin C–based eGFR for confirmation can improve accuracy, especially when tracking small changes over time.

• Manage the “blood pressure load. ” Your kidneys feel every heartbeat. Salt-smart eating, regular movement, and stress-lowering practices help keep pressures steady, which supports filtration long term. In clinical trials, sodium reduction can cut albumin leakage by about half, a kidney-friendly effect that travels with healthier eGFR trends.

• Trim excess weight, preserve muscle. In people with obesity, sustained weight loss (including after bariatric surgery) is linked with preserving or improving eGFR over 6–12 months, while also reducing risk factors like high blood pressure and insulin resistance. Aim for slow, durable fat loss while keeping protein quality high to maintain lean mass.

• Swapping some red and processed meats for beans, lentils, tofu, nuts and whole grains lowers creatinine generation from meat and supports heart, gut and kidney health — a smart combo for better long-term eGFR patterns.

• Hydrate steadily, not excessively. A consistent fluid routine is best for clean comparisons. Simply drinking more water does not reliably slow eGFR decline in most people; instead, avoid frequent dehydration and keep a steady day-to-day pattern.

• Small “biohacks” to try:

  • Evening salt audit: shift more of your salty foods earlier in the day and aim for lower-salt dinners to lighten the overnight blood-pressure burden.

  • Post-meal strolls: 10–15 minutes after meals can trim glucose spikes, easing the kidney’s workload over time.

  • Breath work before bed: 5 minutes of slow nasal breathing or box-breathing can lower sympathetic tone and night-time blood pressure, supporting filtration rhythms.

Units: mL/min/1.73 m².

• Optimal: ≥ 90

• Mildly reduced (often age-appropriate when stable. Track the trend, not just the single value): 60–89, 

• Moderately reduced: 45–59

• Low: 30–44.

• Very low: < 30

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2. eGFR Calculator and 2021 CKD-EPI Race-Free Equation. National Kidney Foundation, 2021–2025. Available from: https://www.kidney.org/professionals/gfr_calculator
   
   

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4. Johnston JG, et al. Circadian regulation of renal function. Am J Physiol Renal Physiol, 2018. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC6052790/
   
   

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6. Lin YC, et al. Effect of Weight Loss on Estimated GFR in Obese Patients, a 1-year Cohort with Propensity Matching. Obesity Surgery, 2019. Available from:https://pmc.ncbi.nlm.nih.gov/articles/PMC6711419/