What is the cut off for impaired renal function?

From the Guidelines

The cut-off for impaired renal function is an estimated glomerular filtration rate (eGFR) below 60 mL/min/1.73 m², as indicated by the most recent and highest quality study 1. This value is used to classify chronic kidney disease (CKD) into different stages, with stage 3 having values between 30-60 mL/min/1.73 m², and stages 4 and 5 having values below 30 and 15 mL/min/1.73 m², respectively.

Key Points to Consider

• The eGFR is calculated using formulas such as the Modification of Diet in Renal Disease (MDRD) formula, the Cockcroft-Gault formula, or the Chronic Kidney Disease EPIdemiology Collaboration (CKD-EPI) formula, which take into account age, gender, ethnicity, and serum creatinine 1.
• Impaired renal function is associated with an increased risk of cardiovascular disease (CVD) and death, with the risk progressively increasing as renal function deteriorates 1.
• Medication dosing adjustments are often necessary in patients with impaired renal function to prevent drug accumulation and toxicity, with common medications requiring adjustment including antibiotics, antivirals, diabetic medications, and anticoagulants 1.

Medication Adjustments

• Metformin should be used cautiously when eGFR is 30-45 mL/min and avoided when below 30 mL/min due to lactic acidosis risk.
• Direct oral anticoagulants generally require dose reductions at eGFR below 50 mL/min, with specific thresholds varying by agent.

Monitoring and Calculation

• It is essential to calculate the current eGFR and check medication-specific renal dosing guidelines when prescribing for patients with renal impairment.
• Regular monitoring of renal function is crucial, especially in those taking nephrotoxic medications or with fluctuating kidney function.

From the FDA Drug Label

Before initiating metformin hydrochloride tablets, obtain an estimated glomerular filtration rate (eGFR). Metformin hydrochloride tablets are contraindicated in patients with an eGFR less than 30 mL/min/1.73 m 2[see Contraindications ( 4) ]. Initiation of metformin hydrochloride tablets is not recommended in patients with eGFR between 30 to 45 mL/min/1. 73 m 2.

The cut off for impaired renal function is an eGFR less than 30 mL/min/1.73 m^2, at which point metformin is contraindicated, and an eGFR between 30 to 45 mL/min/1.73 m^2, at which point initiation of metformin is not recommended 2.

From the Research

Definition of Impaired Renal Function

Impaired renal function is generally defined as an estimated glomerular filtration rate (eGFR) of less than 60 mL/min/1.73 m^2 3. This cutoff is widely used to identify individuals with impaired renal function, which is a significant risk factor for various health complications, including contrast-induced nephropathy (CIN) and cardiovascular disease.

eGFR Cutoffs for Impaired Renal Function

Different studies have used various eGFR cutoffs to define impaired renal function, including:

• eGFR < 60 mL/min/1.73 m^2 3, 4
• eGFR < 30 mL/min/1.73 m^2 5
• eGFR < 15 mL/min/1.73 m^2 4

Factors Influencing eGFR

Several factors can influence eGFR, including:

• Age
• Sex
• Body size
• Diabetes status
• Albuminuria
• Blood pressure 4, 5, 6, 7

Clinical Significance of Impaired Renal Function

Impaired renal function is associated with an increased risk of various health complications, including:

• Contrast-induced nephropathy (CIN) 3
• Cardiovascular disease 6, 7
• Kidney failure 4
• Mortality 5, 6