What can cause a borderline estimated Glomerular Filtration Rate (eGFR) with normal serum creatinine in a 59-year-old female?

From the Guidelines

A borderline eGFR of 61 with a normal creatinine of 90 in a 59-year-old female likely represents early-stage kidney function decline that is common with aging, and warrants monitoring but not immediate intervention. Several factors could contribute to this finding, including hypertension, diabetes, certain medications (particularly NSAIDs like ibuprofen or naproxen), dehydration, or early kidney disease 1. The discrepancy between normal creatinine and borderline eGFR occurs because eGFR calculations account for age, sex, and race, making it more sensitive for detecting early kidney function changes than creatinine alone.

Key Considerations

• After age 40, kidney function typically decreases by about 1% per year, which can lead to a borderline eGFR like in this case 1.
• The use of certain medications, such as NSAIDs, can further decrease kidney function and should be limited or avoided if possible 1.
• Dehydration can also cause a temporary decrease in kidney function, emphasizing the importance of staying well-hydrated 1.
• Early kidney disease, which may not yet be symptomatic, can also contribute to a borderline eGFR, highlighting the need for regular monitoring and follow-up tests.

Recommended Follow-Up

• Blood pressure management to reduce the risk of kidney disease progression 1.
• Blood sugar control if diabetic, as uncontrolled diabetes can damage kidneys over time 1.
• Staying well-hydrated to prevent dehydration-related kidney function decline 1.
• Limiting NSAID use to minimize their potential negative impact on kidney function 1.
• Reducing salt intake and maintaining a healthy weight to reduce the risk of kidney disease and its progression 1.
• Scheduling follow-up kidney function tests in 3-6 months to monitor changes in kidney function over time 1.
• Consulting with a healthcare provider about medication adjustments, particularly for drugs cleared by the kidneys, to prevent drug accumulation and potential adverse effects 1.

From the Research

Potential Causes of Borderline eGFR

• A borderline eGFR of 61 with a normal creatinine of 90 in a 59-year-old female may be caused by various factors, including the use of certain medications such as angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) 2, 3.
• The combination of ACEIs and ARBs has been shown to decrease glomerular filtration rate (GFR) 3, which may contribute to a borderline eGFR.
• However, it is essential to note that the use of ACEIs or ARBs may be beneficial in patients with chronic kidney disease (CKD) or diabetes, as they can help reduce urine albumin excretion and urine protein excretion 3, 4.
• Other factors such as age, sex, and underlying medical conditions may also influence eGFR levels 2.

Medication-Related Effects

• ACEIs and ARBs are commonly used to treat hypertension and CKD, but they can have varying effects on renal function 2, 3.
• The dose and type of ACEI or ARB used may impact eGFR levels, with higher doses potentially leading to greater decreases in GFR 3.
• The combination of ACEIs and ARBs may be more effective than high-dose ACEI or ARB in reducing urine albumin excretion and urine protein excretion, but it may also increase the risk of hypotension 3.

Underlying Medical Conditions

• Diabetes is a significant risk factor for CKD, and the use of ACEIs or ARBs may be beneficial in reducing the risk of kidney disease in patients with diabetes 4.
• Albuminuria, or the presence of albumin in the urine, is a marker of kidney damage and may be associated with a higher risk of CKD 5.
• Hypertension is also a significant risk factor for CKD, and the use of ACEIs or ARBs may be beneficial in reducing blood pressure and slowing the progression of kidney disease 2, 3.