Improving eGFR in Healthy Renal Function: A Measurement Accuracy Issue
In individuals with truly healthy renal function, you cannot and should not attempt to "improve" eGFR—the focus should be on ensuring accurate measurement and preventing future decline, not artificially raising an already normal value.
Understanding the Fundamental Concept
The critical distinction here is that eGFR is an estimate of kidney function, not kidney function itself 1. In someone with genuinely healthy kidneys (eGFR >90 mL/min/1.73 m²), the goal is preservation, not improvement 1.
When eGFR Appears Low Despite Healthy Kidneys
If eGFR appears suboptimal but you suspect healthy renal function, the issue is likely measurement inaccuracy due to non-GFR determinants rather than actual kidney dysfunction 1:
Confirm accuracy with cystatin C-based eGFR (eGFRcys or eGFRcr-cys) if the creatinine-based estimate seems inaccurate due to extremes of muscle mass, dietary factors (vegetarian diet, low protein intake), or certain medications 1
Consider measured GFR using exogenous filtration markers if both creatinine and cystatin C-based estimates are thought to be inaccurate and clinical decisions depend on precise GFR assessment 1
Preventing Decline in Healthy Kidneys
For individuals with confirmed healthy renal function, the evidence-based approach focuses on prevention strategies 1:
Lifestyle Modifications That Preserve Kidney Function
Intensive weight-loss lifestyle intervention with Mediterranean diet and increased physical activity can slow eGFR decline by approximately 0.58 mL/min/1.73 m²/year compared to usual care, and reduce the incidence of moderately impaired eGFR by 40% 2
Smoking cessation is essential for kidney health preservation 1
Optimal blood pressure control (target systolic BP <120 mmHg for most patients, though individual preferences may vary) helps prevent future kidney damage 1
Cardiovascular Risk Factor Management
Glycemic control is crucial—fasting blood sugar above 7.4 mmol/L correlates with additional eGFR decline of 0.043 mL/min/1.73 m²/year 3
Statins may contribute to kidney function preservation (improvement of 0.34 mL/min/1.73 m²/year in some populations) 3
Avoid nephrotoxins and ensure appropriate medication dosing 1
Critical Caveats
Do not pursue interventions to artificially raise eGFR in healthy individuals—this represents a fundamental misunderstanding of kidney physiology. The kidney already functions optimally at baseline in healthy persons 1.
Age-related decline is physiologic: eGFR naturally declines with aging, and this does not necessarily represent pathology requiring intervention 4, 5.
Muscle mass changes confound interpretation: Weight loss interventions may paradoxically lower creatinine-based eGFR due to muscle loss rather than true kidney function decline 4. This is why cystatin C-based estimates are valuable in these contexts 1.