Strategies to Increase Glomerular Filtration Rate (GFR)
Blood pressure control with ACE inhibitors or ARBs is the most effective intervention to increase or preserve GFR in patients with kidney disease. 1
Understanding GFR and Its Determinants
GFR is determined by several physiological factors:
- Renal autoregulation mechanisms
- Systemic blood pressure
- Intraglomerular pressure
- Afferent and efferent arteriolar tone
- Functioning nephron mass
In many kidney diseases, dysfunctional autoregulation leads to transmission of systemic pressure to the glomerulus, causing damage and progressive GFR decline 1.
Evidence-Based Interventions to Increase GFR
1. Blood Pressure Management
- Target: <130/80 mmHg 1
- First-line agents: ACE inhibitors (like lisinopril) or ARBs (like losartan) 1, 2
- Mechanism: These medications preferentially dilate the efferent arteriole, reducing intraglomerular pressure while maintaining GFR 1
- Caution: Monitor for acute decline in renal function, especially in patients with bilateral renal artery stenosis or advanced renal disease 1, 3, 4
2. Dietary Modifications
- Protein intake: Limit to 0.8 g/kg/day (adult RDA) for patients with overt nephropathy 1
- Sodium restriction: Limit to <2.0 g/day 1, 2
- Avoid Western diet: High intake of processed foods preserved with salt and phosphate can worsen kidney function 1
3. Glycemic Control
- Target: HbA1c <7% (individualized based on patient characteristics) 2
- Mechanism: Hyperglycemia contributes to hyperfiltration, which can damage kidneys over time 5
- Importance: Poor glycemic control accelerates loss of kidney function, especially in diabetic patients 1, 2
4. Weight Management
- Obesity is associated with hyperfiltration and increased risk of rapid GFR decline 6
- Weight loss can improve GFR in overweight individuals with kidney disease 1
5. Management of Edema (if present)
- Loop diuretics as first-line therapy 1
- Consider combination with thiazide diuretics for resistant edema 1
- Monitor for adverse effects including hypokalemia, hyponatremia, and impaired GFR 1
Special Considerations
For Diabetic Patients
- ACE inhibitors have shown convincing evidence of reducing kidney disease progression in type 1 diabetes with nephropathy 1
- For type 2 diabetes with nephropathy, ARBs have demonstrated superiority in slowing progressive loss of kidney function 1, 2
- Start ACE inhibitors or ARBs for patients with any degree of albuminuria 2
For Children and Adolescents
- Consider ACE inhibitors or ARBs for confirmed hypertension in children with diabetes 1
- Target blood pressure <90th percentile for age, sex, and height or <130/80 mmHg in adolescents ≥13 years 1
- Reproductive counseling is essential for females of childbearing age due to teratogenic effects 1
Monitoring Recommendations
- Regular assessment of GFR using creatinine-based estimated GFR (eGFRcr) 1
- Consider cystatin C measurement and eGFRcr-cys for more accurate assessment when needed 1
- Monitor serum potassium levels when using ACE inhibitors or ARBs 3, 4
- Temporarily suspend ACE inhibitors or ARBs during episodes of dehydration or acute illness 2
Common Pitfalls to Avoid
Don't ignore acute GFR decline after starting ACE inhibitors/ARBs: A small increase in serum creatinine (up to 30%) is acceptable, but discontinue if kidney function continues to worsen 1
Avoid dual RAS blockade: Combining ACE inhibitors with ARBs increases risks of hyperkalemia and acute kidney injury without additional benefit 4
Don't overlook non-GFR determinants of serum creatinine: Diet (vegetarian, high-protein, keto), muscle mass, and certain medications can affect creatinine levels without reflecting true GFR changes 1
Beware of hyperfiltration: While a high GFR might seem beneficial, renal hyperfiltration is associated with increased risk of cardiovascular disease and mortality 7
Don't rely solely on estimated GFR: Consider measured GFR using exogenous filtration markers when more accurate assessment is needed for clinical decision-making 1