From the Guidelines
Management of a patient with declining renal function from a GFR of 46 to 38 ml/min requires prompt intervention to prevent further deterioration, with a focus on controlling blood pressure, optimizing glycemic control, and adjusting medication dosages, as recommended by the most recent guidelines 1. The patient's decline in GFR from 46 to 38 ml/min indicates a progression to CKD Stage 3b, which requires careful management to slow disease progression and prevent complications.
- Identify and address underlying causes such as hypertension, diabetes, or medication toxicity.
- Blood pressure should be controlled to a target of <130/80 mmHg using ACE inhibitors or ARBs (like lisinopril 10-40 mg daily or losartan 25-100 mg daily), which provide renoprotection by reducing intraglomerular pressure, as supported by the 2020 guidelines 1.
- For diabetic patients, optimize glycemic control with a target HbA1c of 7-8%, potentially adjusting medications like metformin (maximum 1000 mg daily with GFR <45) or switching to renal-safe alternatives.
- Review and adjust medication dosages for renally-cleared drugs, and discontinue nephrotoxic agents including NSAIDs and certain antibiotics.
- Implement dietary modifications including sodium restriction (<2.3g/day), moderate protein intake (0.8g/kg/day), and potassium restriction if hyperkalemia develops.
- Monitor renal function with serum creatinine, electrolytes, and urinalysis every 3-6 months, with more frequent testing if GFR continues to decline, as suggested by the Canadian Society of Nephrology commentary 1. Consider nephrology referral at this stage (CKD Stage 3b) for specialized management, particularly if there's rapid progression, significant proteinuria, or difficult-to-control complications like anemia or metabolic bone disease, as recommended by the KDIGO clinical practice guideline 1.
From the Research
Management of Impaired Renal Function
The patient's decreased Glomerular Filtration Rate (GFR) from 46 to 38 indicates impaired renal function. The following management steps can be considered:
- Identification of patients at risk: Patients with pre-existing renal insufficiency, diabetes, advanced age, congestive heart failure, and dehydration are at higher risk of contrast-induced nephropathy (CIN) 2.
- Hydration: Patients should be well-hydrated to prevent CIN 2, 3.
- Withdrawal of nephrotoxic medications: Nephrotoxic medications should be withdrawn at least 24 hours prior to contrast media administration 2.
- Use of minimal necessary contrast media dose: The nephrotoxic effect of contrast media is dose-dependent, and the minimal necessary dose should be used 2.
- Selection of contrast media: The incidence of CIN is lower when an iso-osmolar contrast media is used instead of a low-osmolar contrast media in patients with renal insufficiency and diabetes 2.
- Estimation of GFR: GFR should be estimated before contrast media administration to identify patients at risk 2, 4.
- Monitoring of serum creatinine levels: Serum creatinine levels should be monitored before and after contrast media administration to detect any changes in renal function 5, 3, 6.
Prevention of Contrast-Induced Nephropathy
Several studies have investigated the prevention of CIN:
- N-acetylcysteine (NAC) has been shown to be beneficial in preventing CIN in some studies 5, but its effectiveness is still debated 2, 6.
- Calcium channel blockers and angiotensin receptor blockers have not been consistently shown to reduce the incidence of CIN 2, 6.
- Volume expansion with saline hydration is the only therapy that has been consistently shown to reduce the risk of CIN 6.