What does an eGFR of 91.1 indicate about kidney function?

eGFR of 91.1 Indicates Normal Kidney Function

An eGFR of 91.1 mL/min/1.73 m² represents normal kidney function, classified as CKD Stage 1 (GFR ≥90), which requires no specific intervention unless markers of kidney damage are present. 1

Understanding Your Kidney Function Values

Your laboratory results show:

• Creatinine 0.75 mg/dL: This is within normal range and actually on the lower end 2
• eGFR 91.1 mL/min/1.73 m²: This indicates normal or high kidney function 1
• BUN/Creatinine ratio 26.67: This is elevated (normal is typically 10-20:1) 2

Clinical Interpretation

Normal Kidney Function Stage

• Your eGFR places you in CKD Stage 1, defined as GFR ≥90 mL/min/1.73 m² 1
• Stage 1 indicates normal or high glomerular filtration rate 1
• At this level, kidney function is considered excellent and requires no treatment unless other abnormalities exist 1

The Elevated BUN/Creatinine Ratio

The most clinically significant finding is your elevated BUN/Creatinine ratio of 26.67, which suggests pre-renal factors, most commonly dehydration. 2

Key considerations:

• Dehydration is the most likely explanation for this ratio with preserved kidney function 2
• Your low creatinine (0.75) may reflect decreased muscle mass, which is common with aging or reduced physical activity 2
• The combination of normal eGFR with elevated BUN/Creatinine ratio indicates the kidneys themselves are functioning well, but external factors are affecting the blood urea nitrogen level 2

What This Means Clinically

No Kidney Disease Present

• An eGFR >90 mL/min/1.73 m² without proteinuria or other markers of kidney damage does not constitute chronic kidney disease 1
• You do not meet criteria for any stage of kidney dysfunction requiring medical intervention 1

Important Caveats About eGFR Interpretation

eGFR accuracy is suboptimal in patients with normal or near-normal renal function, and the actual GFR range for your values could be quite variable. 3, 4

Factors affecting eGFR accuracy:

• Low muscle mass can cause artificially elevated eGFR calculations because creatinine production is reduced 2, 3
• Age, sex, and race are incorporated into the calculation but may not fully account for individual variation 4
• The eGFR represents a population average, not a precise measurement for your specific case 3

When eGFR Alone Is Insufficient

For patients with diabetes, an eGFR <90 mL/min may represent significant kidney function loss even though it appears "normal," because diabetic patients often have elevated GFR in early disease. 1

Additional evaluation is needed if you have:

• Diabetes mellitus with poor glycemic control 1
• Hypertension 1
• Proteinuria or albuminuria (≥30 mg/g on urine albumin-to-creatinine ratio) 1
• Family history of kidney disease 1

Recommended Actions

Immediate Assessment

• Evaluate for clinical signs of dehydration: dry mucous membranes, decreased skin turgor, orthostatic symptoms 2
• Assess muscle mass: low creatinine may indicate reduced muscle mass, which can falsely elevate eGFR 2
• Check for medications that might affect BUN levels (NSAIDs, diuretics, ACE inhibitors) 2

Follow-Up Testing

• Urine albumin-to-creatinine ratio should be checked if not already done, as kidney damage can exist with normal eGFR 1
• Repeat testing after adequate hydration to see if BUN/Creatinine ratio normalizes 2
• Consider cystatin C-based eGFR if low muscle mass is suspected, as this provides more accurate assessment in such patients 2, 3

Monitoring Frequency

• Annual screening is recommended if you have diabetes or hypertension, including eGFR and urine albumin measurement 1
• For healthy individuals without risk factors, routine monitoring follows standard preventive care guidelines 1

Critical Pitfall to Avoid

Do not rely solely on eGFR in patients with very low muscle mass, as this can provide false reassurance about kidney function. 2 The combination of low creatinine (0.75) with normal eGFR may mask underlying kidney issues if muscle mass is significantly reduced. If clinical suspicion exists for kidney disease despite normal eGFR, consider measured GFR using exogenous filtration markers or cystatin C-based equations 3, 5.