Do a blood urea nitrogen of 7 mg/dL, serum creatinine of 0.63 mg/dL, and estimated glomerular filtration rate of 114 mL/min/1.73 m² indicate normal renal function?

Assessment of Renal Function with BUN 7 mg/dL, Creatinine 0.63 mg/dL, and eGFR 114 mL/min/1.73m²

These laboratory values indicate normal to supranormal renal function, with no evidence of kidney impairment.

Interpretation of Individual Parameters

Estimated Glomerular Filtration Rate (eGFR)

• An eGFR of 114 mL/min/1.73 m² is well above the threshold for chronic kidney disease (CKD), which begins at values below 60 mL/min/1.73 m² 1.
• This eGFR falls within the normal range and indicates excellent glomerular filtration capacity 1.
• Values above 90 mL/min/1.73 m² are considered normal kidney function in the absence of other markers of kidney damage 1.

Serum Creatinine

• A creatinine of 0.63 mg/dL is within the normal range and does not suggest renal impairment 1.
• The European Society of Hypertension/Cardiology guidelines note that serum creatinine values in the normal range, when used to calculate eGFR, help detect kidney function accurately 1.
• This creatinine level, combined with the eGFR calculation, provides reliable evidence of normal filtration 2.

Blood Urea Nitrogen (BUN)

• A BUN of 7 mg/dL is at the lower end of the normal reference range (typically 7-20 mg/dL) but does not indicate pathology 3.
• Low-normal BUN can reflect adequate hydration, lower protein intake, or excellent renal clearance 3.
• Research demonstrates that BUN values below 16-17 mg/dL in cardiovascular patients are associated with the lowest mortality risk, indicating this is a favorable finding 4, 5.

BUN-to-Creatinine Ratio Analysis

• The BUN/creatinine ratio is approximately 11:1 (7 ÷ 0.63), which is well below the threshold of 20:1 that suggests prerenal azotemia 3.
• This low ratio confirms adequate renal perfusion and normal tubular function 3.
• The absence of an elevated ratio excludes volume depletion, heart failure, or reduced renal perfusion as contributing factors 3.

Clinical Significance

No Evidence of Kidney Disease

• All three parameters—BUN, creatinine, and eGFR—consistently indicate normal renal function with no signs of acute or chronic kidney disease 1.
• The absence of proteinuria, hematuria, or structural abnormalities would further confirm normal kidney status, though these were not provided 1.

Context-Dependent Considerations

• In patients with reduced muscle mass (elderly, malnourished, or female patients), serum creatinine may underestimate the degree of renal impairment, but the eGFR calculation accounts for age and sex to provide a more accurate assessment 1.
• The low-normal BUN may reflect dietary protein intake rather than renal pathology; however, in the context of normal creatinine and eGFR, this is not concerning 6.

Monitoring Recommendations

• No specific renal monitoring beyond routine health maintenance is required for these values 1.
• If the patient has risk factors for CKD (diabetes, hypertension, cardiovascular disease), annual screening with creatinine, eGFR, and urine albumin-to-creatinine ratio is appropriate 1.
• A repeat assessment in 3-6 months would only be indicated if new symptoms or risk factors emerge 3.

Common Pitfalls to Avoid

• Do not misinterpret the low-normal BUN as a sign of liver disease or malnutrition without additional clinical context 3.
• Do not assume that a single set of normal values excludes the possibility of early kidney disease if proteinuria or other markers of kidney damage are present 1.
• Recognize that eGFR equations may be less accurate at the extremes of GFR (very high or very low), but at 114 mL/min/1.73 m², the estimate is reliable 2.