From the Guidelines
A GFR of 66 ml/min/1.73m² with a creatinine of 117 μmol/L indicates mild kidney dysfunction, specifically Stage 2 Chronic Kidney Disease, and requires monitoring and management to prevent progression. This condition is characterized by a reduced kidney function, which can be detected through routine laboratory measurements, as stated in the national kidney foundation practice guidelines for chronic kidney disease 1. The guidelines define chronic kidney disease as either kidney damage or decreased kidney function (decreased GFR) for 3 or more months.
Key Considerations
- The GFR level of 66 ml/min/1.73m² represents a loss of about 30-40% of the adult level of normal kidney function, which is a significant reduction but not severe enough to require immediate intervention.
- The elevated serum creatinine of 117 μmol/L is slightly above the normal range, which aligns with the reduced GFR.
- According to the kidney disease: improving global outcomes 2012 clinical practice guideline, persons with CKD should be assessed at least annually, and the exact frequency of GFR and albuminuria monitoring will depend on the severity of CKD 2.
- Lifestyle modifications are crucial, including maintaining adequate hydration, following a balanced diet moderate in protein and low in sodium, exercising regularly, avoiding smoking, and limiting alcohol consumption.
Management and Monitoring
- Controlling blood pressure (target below 130/80 mmHg) and managing diabetes if present (aim for HbA1c below 7%) are essential to prevent progression of kidney disease.
- Avoiding nephrotoxic medications like NSAIDs (ibuprofen, naproxen) is also recommended.
- The frequency of monitoring should be guided by the risk for progression, which can be assessed using the GFR and albuminuria grid provided in the guideline 2.
- Small fluctuations in GFR are common and do not necessarily indicate progression, but an approach involving an assessment of change in eGFR category confirmed by a minimal percentage of change in eGFR (25% or greater) was recommended to define progression 2.
From the Research
Implications of a Glomerular Filtration Rate (GFR) of 66 with Elevated Serum Creatinine of 117
- A GFR of 66 indicates mild renal impairment, and an elevated serum creatinine level of 117 suggests a potential decline in renal function 3.
- According to the study by 4, patients with preexisting chronic renal insufficiency who achieve blood pressure control goals are likely to demonstrate an early rise in serum creatinine levels, which may stabilize after about 4 weeks.
- The use of angiotensin-converting enzyme (ACE) inhibitors in patients with heart failure and renal insufficiency may slow the progression of renal disease, despite an initial rise in serum creatinine levels 4.
- However, the study by 5 suggests that combination therapy with an ACE inhibitor and an angiotensin II receptor blocker (ARB) may not be more effective than monotherapy with an ACE inhibitor or ARB and may increase the risk of hyperkalemia or acute kidney injury.
- The estimation of GFR using creatinine-based formulas, such as the Cockcroft-Gault and Modification of Diet in Renal Disease Study equations, has limitations and may not accurately reflect the actual GFR 3.
- Alternative filtration markers, such as cystatin C, beta-trace protein, and beta-2 microglobulin, may be less dependent on age and sex, but equations combining these markers have not been extensively investigated in patients with chronic kidney disease (CKD) 6.
- The study by 7 highlights the importance of considering the pharmacokinetic properties of ACE inhibitors in patients with renal insufficiency, as renal clearance decreases and peak plasma concentrations increase, leading to potential drug accumulation.
- Patients with a GFR of 66 and elevated serum creatinine should be closely monitored for signs of worsening renal function, and their treatment plan should be adjusted accordingly, taking into account the potential benefits and risks of ACE inhibitors and other medications 4, 7, 5.