What is the management approach for a patient with an estimated Glomerular Filtration Rate (eGFR) of 35, indicating Impaired renal function?

From the Guidelines

For a patient with an eGFR of 35, the management approach should prioritize renoprotection and cardiovascular risk reduction, with careful monitoring of renal function and serum potassium levels, as recommended by the American Heart Association and the Heart Failure Society of America 1.

Management Approach

The management of a patient with an eGFR of 35 mL/min/1.73m², indicating Stage 3b chronic kidney disease (CKD), should focus on slowing disease progression and addressing complications.

• The cornerstone of treatment includes blood pressure control targeting <130/80 mmHg, preferably with an ACE inhibitor (like enalapril 5-20 mg daily) or ARB (such as losartan 25-100 mg daily) which provide renoprotection by reducing intraglomerular pressure.
• Medication dosing adjustments are essential; drugs cleared by the kidneys like metformin should be reduced to a maximum of 1000 mg daily, and nephrotoxic medications including NSAIDs and certain antibiotics should be avoided.
• Regular monitoring should include quarterly checks of serum creatinine, electrolytes, and urinary albumin-to-creatinine ratio.
• Dietary modifications are important, including moderate protein restriction (0.8 g/kg/day), sodium limitation (<2 g/day), and potassium restriction if hyperkalemia develops.
• Patients should be screened for complications including anemia, metabolic acidosis, and mineral bone disorders with appropriate supplementation of vitamin D if deficient.
• Cardiovascular risk reduction is crucial through statin therapy, smoking cessation, and glycemic control in diabetic patients (targeting HbA1c around 7%) 1.

Renal Function Monitoring

The frequency of renal monitoring in heart failure patients with reduced eGFR should be based on a patient-based monitoring regimen, considering both medication and individual risk factors, and suggesting a monitoring interval based on a patient’s combined risk, facilitating early intervention to reduce risk of renal deterioration, hospital admission, and mortality 1.

• Estimated GFR is derived from serum creatinine using formulae that include age, sex, and ethnicity, and it is valid to use eGFR to monitor renal function over months and years.
• Serum creatinine should be used to monitor more acute changes in renal function.
• The trend in creatinine (or eGFR over months) is more important than the absolute value when monitoring renal function in the context of initiation and titration of drugs.

From the FDA Drug Label

Patients with renal insufficiency have elevated plasma concentrations of losartan and its active metabolite compared to subjects with normal renal function. No dose adjustment is necessary in patients with renal impairment unless a patient with renal impairment is also volume depleted [see DOSAGE AND ADMINISTRATION (2.3), WARNINGS AND PRECAUTIONS (5. 3) and CLINICAL PHARMACOLOGY (12.3)]. Safety and effectiveness have not been established in pediatric patients under the age of 6 or in pediatric patients with glomerular filtration rate <30 mL/min/1.73 m2

The management approach for a patient with an eGFR of 35 should be cautious, as this indicates impaired renal function.

• Dose adjustment may not be necessary unless the patient is also volume depleted.
• Monitoring of renal function and electrolytes is crucial.
• Avoid combined use of RAS inhibitors, such as ACE inhibitors or aliskiren, especially in patients with diabetes or renal impairment 2 2.

From the Research

Management Approach for Impaired Renal Function

The management approach for a patient with an estimated Glomerular Filtration Rate (eGFR) of 35, indicating impaired renal function, involves careful consideration of drug dosages and potential nephrotoxicity.

• Drug nephrotoxicity is a significant concern in patients with impaired renal function, as many therapeutic agents can cause renal damage, particularly when the serum half-life is prolonged and blood levels are raised due to decreased renal excretion 3.
• The glomerular filtration rate (GFR) decreases with age, and an otherwise healthy person of 80 may have an estimated GFR (eGFR) of <60 mL/min or <50 mL/min, i.e., stage 2,3, or 3b chronic kidney disease (CKD) 3.
• Certain drugs, such as non-steroidal anti-inflammatory drugs, aspirin, and angiotensin-converting enzyme inhibitors, can worsen hypertension, increase bruising or bleeding tendency, and cause hyponatraemia hypertension acidosis in patients with impaired renal function 3.
• Digoxin is contraindicated in stage 3 CKD, even in reduced dosage, and other drugs can cause direct formation of kidney stones or rupture of the Achilles tendon 3.

Drug Dosage Adjustment

• Drug dosage adjustment is crucial in patients with impaired renal function to prevent accumulation and toxicity 4.
• The dose of lisinopril, an angiotensin-converting enzyme inhibitor, should be adjusted to the pretreatment GFR, and a decrease in dosage should be considered with prolonged treatment 5.
• However, there is a lack of consistency in dosing information among drug information sources, and an evidence-based approach to drug dosage adjustment is necessary to bring uniformity to the recommendations 6.

Monitoring and Treatment

• Regular monitoring of drug concentrations and renal function is essential to avoid drug toxicity and ensure effective treatment 4.
• Lisinopril has been shown to be effective in controlling blood pressure in patients with hypertension associated with impaired renal function, with a median dose of 10 mg daily 7.
• The management approach should involve a systematic approach, including calculating the patient's glomerular filtration rate, choosing and administering a loading dose, determining a maintenance dose, and deciding on monitoring of drug concentrations 4.