What type of kidney injury is indicated by a BUN of 6 and creatinine of 1.19?

Assessment of Kidney Injury with BUN 6 and Creatinine 1.19

Based on the laboratory values provided (BUN 6 mg/dL and creatinine 1.19 mg/dL), this patient does not have acute kidney injury but rather has normal kidney function.

Analysis of Laboratory Values

The provided laboratory values need to be interpreted in the context of established criteria for kidney injury:

• Creatinine level of 1.19 mg/dL: This value is within or slightly above the normal range for most adults (0.7-1.2 mg/dL), depending on the patient's age, gender, and muscle mass 1.

• BUN level of 6 mg/dL: This is actually at the lower end of the normal range (6-20 mg/dL) 1.

• BUN:Creatinine ratio: The ratio is approximately 5:1, which is lower than the normal ratio of 10-15:1 2.

Diagnostic Criteria for Acute Kidney Injury

According to the KDIGO criteria, acute kidney injury is defined by 1:

• Increase in serum creatinine by ≥0.3 mg/dL within 48 hours, OR
• Increase in serum creatinine to ≥1.5 times baseline within 7 days, OR
• Urine volume <0.5 mL/kg/h for 6 hours

The International Club of Ascites criteria similarly define AKI as 1:

• Increase in serum creatinine ≥0.3 mg/dL within 48 hours, OR
• A percentage increase in serum creatinine of ≥50% from baseline

Clinical Interpretation

1. No evidence of AKI: The provided values do not meet any criteria for acute kidney injury, as we don't have baseline values showing an increase in creatinine 1.

2. Normal kidney function: The creatinine level of 1.19 mg/dL is within or slightly above normal range, suggesting preserved glomerular filtration rate.

3. Low-normal BUN: The BUN of 6 mg/dL is at the lower end of normal range, which could reflect:

   • Adequate hydration
   • Low protein intake or malnutrition
   • Possible liver dysfunction (decreased urea production)
   • Pregnancy (physiologic decrease in BUN) 1, 2

4. Low BUN:Creatinine ratio: The ratio of approximately 5:1 is lower than the normal 10-15:1, which may suggest:

   • Liver dysfunction with decreased urea production
   • Malnutrition or low protein intake
   • Overhydration 3, 2

Clinical Implications

The laboratory values suggest normal kidney function without evidence of acute kidney injury. The low-normal BUN with a relatively normal creatinine may warrant investigation for:

• Nutritional status (protein intake, malnutrition)
• Liver function (decreased urea synthesis)
• Volume status (possible overhydration)
• Pregnancy status (if applicable)

Key Takeaway

These laboratory values do not indicate kidney injury but rather reflect normal kidney function with a relatively low BUN level that may be due to various physiological or pathological conditions unrelated to kidney injury.