GFR (Glomerular Filtration Rate)
The rate at which kidneys filter blood, a key marker of renal function
Definition
The Glomerular Filtration Rate (GFR) is the volume of plasma filtered by the kidneys per minute. It is the single best measure of kidney function, usually estimated (eGFR) using creatinine, age, sex, and body size.
Normal and CKD Stages
- Normal: ≥90 mL/min/1.73 m²
- Stage 1 CKD: ≥90 with kidney damage
- Stage 2: 60 to 89
- Stage 3a: 45 to 59
- Stage 3b: 30 to 44
- Stage 4: 15 to 29
- Stage 5 (ESRD): less than 15. Dialysis or transplant
Clinical Implications
Low GFR requires dose adjustment of renally excreted medications (antibiotics, digoxin, metformin, opioids). Contrast media may worsen GFR. Ensure hydration and weigh risk-benefit. Monitor potassium, phosphorus, bicarbonate, and hemoglobin.
Nursing Considerations
Teach CKD patients about fluid restrictions, dietary restrictions (sodium, potassium, phosphorus), and medication avoidance (NSAIDs, contrast).
NCLEX Relevance
GFR less than 60 = CKD. Less than 15 = ESRD.