From the Guidelines
Management of a patient with a GFR of 50 mL/min/1.73m² requires careful monitoring and medication adjustments, with a focus on preserving remaining kidney function and preventing complications, as outlined in the most recent guidelines 1. This patient has Stage 3a chronic kidney disease and needs regular assessment of kidney function every 3-6 months. Medication dosing should be adjusted for renally cleared drugs, with particular attention to NSAIDs, certain antibiotics like aminoglycosides, and metformin which may need dose reduction, as recommended by the Canadian Society of Nephrology commentary on the KDIGO clinical practice guideline for CKD evaluation and management 1. Blood pressure control is essential, targeting <130/80 mmHg, typically using ACE inhibitors or ARBs as first-line agents, which help reduce proteinuria and slow CKD progression, as suggested by the national kidney foundation practice guidelines for chronic kidney disease 1. Lifestyle modifications are crucial, including:
- Sodium restriction to <2g daily
- Moderate protein intake (0.8g/kg/day) as recommended for patients with diabetic kidney disease 1
- Smoking cessation
- Regular exercise Patients should avoid nephrotoxic agents when possible and maintain adequate hydration. Metabolic complications should be monitored, including anemia, acidosis, and mineral bone disorders. Referral to a nephrologist is not immediately necessary for a GFR of 50, but should be considered if the patient's condition worsens or if the primary care physician cannot adequately manage the patient's care, as suggested by the national kidney foundation practice guidelines for chronic kidney disease 1. This approach addresses both the preservation of remaining kidney function and prevention of complications, as the kidneys at this stage still maintain adequate clearance of waste products but have reduced reserve capacity.
From the FDA Drug Label
5.3 Impaired Renal Function Monitor renal function periodically in patients treated with lisinopril. Changes in renal function including acute renal failure can be caused by drugs that inhibit the renin-angiotensin system. Patients whose renal function may depend in part on the activity of the renin-angiotensin system (e.g., patients with renal artery stenosis, chronic kidney disease, severe congestive heart failure, post-myocardial infarction or volume depletion) may be at particular risk of developing acute renal failure on lisinopril. Consider withholding or discontinuing therapy in patients who develop a clinically significant decrease in renal function on lisinopril [see Adverse Reactions (6. 1), Drug Interactions (7.4)].
Management Approach for a Patient with Impaired Renal Function (GFR 50):
- Monitor renal function periodically while the patient is being treated with lisinopril.
- Be aware of the potential risk of developing acute renal failure, especially since the patient's renal function may depend on the activity of the renin-angiotensin system.
- Consider the patient's overall clinical condition and adjust the treatment plan as necessary to minimize the risk of adverse effects on renal function.
- Withhold or discontinue therapy if the patient develops a clinically significant decrease in renal function while on lisinopril 2.
- Dosing considerations: The elimination half-life of lisinopril is little changed when the glomerular filtration rate is above 30 mL/min. However, with greater impairment, peak and trough lisinopril levels increase, and time to attain steady state is prolonged 2.
From the Research
Management Approach for Impaired Renal Function
A patient with a Glomerular Filtration Rate (GFR) of 50 is considered to have impaired renal function, specifically stage 3 chronic kidney disease (CKD) [ 3 ]. The management approach for such a patient involves:
- Cardiovascular risk reduction, including the use of statins and blood pressure management [ 3 ]
- Treatment of albuminuria, such as angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers [ 3 ]
- Avoidance of potential nephrotoxins, including nonsteroidal anti-inflammatory drugs [ 3 ]
- Adjustments to drug dosing, including many antibiotics and oral hypoglycemic agents [ 3 ]
Monitoring and Referral
Patients with impaired renal function require monitoring for complications of CKD, including:
- Hyperkalemia
- Metabolic acidosis
- Hyperphosphatemia
- Vitamin D deficiency
- Secondary hyperparathyroidism
- Anemia [ 3 ]
Those at high risk of CKD progression, such as patients with an estimated GFR <30 mL/min/1.73 m2, albuminuria ≥300 mg per 24 hours, or rapid decline in estimated GFR, should be promptly referred to a nephrologist [ 3 ].
Role of ACE Inhibitors
ACE inhibitors can be beneficial in reducing proteinuria and slowing the progression of CKD, but may also increase the risk of acute renal failure in certain patients, such as those with heart failure or severe depletion of circulating volume [ 4 ].
Measurement of GFR
Measurement of GFR can be useful in individualizing therapy among patients with CKD, particularly in situations where estimated GFR is known to provide imprecise estimates of glomerular function [ 5 ].
Primary Care Management
Most patients with CKD can be managed in primary care, with serial follow-up essential to identify patients at high risk of progression to advanced stages of CKD [ 6 ]. Primary care providers should work together with local nephrologists to improve the lives of those living with CKD [ 7 ].