What are the implications of a Glomerular Filtration Rate (GFR) of 45, indicating Impaired renal function?

From the Guidelines

A GFR of 45 mL/min/1.73m² indicates moderate kidney disease, specifically Stage 3B chronic kidney disease (CKD), requiring regular monitoring and management. This level of kidney function is associated with an increased risk of adverse outcomes, such as cardiovascular disease and progression to end-stage renal disease 1.

Key Management Strategies

• Regular monitoring of kidney function every 3-6 months
• Blood pressure control, typically aiming for below 130/80 mmHg using medications like ACE inhibitors or ARBs when appropriate
• Diet modifications, including moderate protein intake (0.8 g/kg/day), reduced sodium (less than 2,300 mg daily), and potassium restrictions if levels are elevated
• Avoidance of nephrotoxic medications like NSAIDs (ibuprofen, naproxen) and certain antibiotics when possible
• Management of other conditions like diabetes (targeting HbA1c below 7%) and addressing cardiovascular risk factors
• Lifestyle changes, including regular exercise, maintaining a healthy weight, smoking cessation, and limiting alcohol consumption According to the KDIGO 2012 CKD guideline, a classification framework for CKD that includes GFR categories, cause, and albuminuria categories is recommended 1.

Importance of Albuminuria

• Albuminuria is a key dimension in risk assessment for CKD
• A practical table describing the relationships between protein-to-creatinine ratio to dipsticks and urine albumin-to-creatinine ratio (ACR) is provided
• The use of the term ‘microalbuminuria’ is discouraged, and more quantitative description of albuminuria by category or by specific value is encouraged 1. This GFR level means the kidneys are functioning at about 45% of normal capacity, and while serious, proper management can often slow further decline. It is essential to work with a nephrologist to develop a personalized management plan.

From the FDA Drug Label

Initiation of metformin hydrochloride tablets is not recommended in patients with eGFR between 30 to 45 mL/min/1. 73 m 2. In patients taking metformin hydrochloride tablets whose eGFR falls below 45 mL/min/1. 73 m 2, assess the benefit and risk of continuing therapy. Metformin hydrochloride tablets are contraindicated in patients with an eGFR less than 30 mL/min/1.73 m 2 Initiation of metformin hydrochloride tablets in patients with an eGFR between 30 to 45 mL/minute/1. 73 m 2is not recommended. In patients taking metformin hydrochloride tablets whose eGFR later falls below 45 mL/min/1.73 m 2, assess the benefit risk of continuing therapy.

Metformin is not recommended for patients with a GFR of 45, as the eGFR is at the border of the recommended range. According to the label, initiation is not recommended for patients with an eGFR between 30 to 45 mL/min/1.73 m 2 2 2.

From the Research

Definition and Stages of Chronic Kidney Disease (CKD)

• Chronic Kidney Disease (CKD) is a condition characterized by a gradual loss of kidney function over time.
• The stages of CKD are defined based on the estimated glomerular filtration rate (eGFR), which is a measure of kidney function.
• A GFR of 45 mL/min/1.73 m2 or lower indicates stage 3b or higher CKD, as stated in the study by 3.

Management and Treatment of CKD

• The management of CKD involves slowing the progression of the disease through various treatments, including the use of renin-angiotensin system (RAS) blockers, such as angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) 4.
• RAS blockers have been shown to have renoprotective effects in patients with CKD, particularly those with high albuminuria.
• However, the use of RAS blockers in patients with advanced CKD is often limited due to concerns about hyperkalemia or acute renal decline.

Risk of Renal Failure in CKD

• Patients with stage 3b CKD are at high risk of renal failure, with a 20% risk of developing renal failure within 2 years, as reported in the study by 5.
• The risk of renal failure in patients with CKD is often under-recognized in standard medical screening, highlighting the need for early detection and treatment.
• The use of ACEIs or ARBs has been shown to reduce the risk of kidney failure in patients with advanced CKD, as demonstrated in the study by 6.

Treatment Patterns and Initiation

• Many patients with diabetes and CKD experience a delay in treatment or fail to initiate treatment with guideline-recommended ACEIs or ARBs after CKD diagnosis, as found in the study by 7.
• Only 17% of patients with type 2 diabetes and CKD initiated ACEI or ARB therapy within a year after meeting CKD criteria, highlighting a need for improved treatment patterns and initiation.