A 35-year-old man (height 67 inches, weight 73.3 kg) with known chronic renal disease for 6 months has blood drawn for serum creatinine and urea tests. Urine is collected for a 24-hour quantitative creatinine test; the total volume of urine collected is 1139 mL. The following laboratory results are obtained for the testing done: Urine creatinine: 56 mg/dL Serum creatinine: 9.6 mg/dL Serum urea: 75 mg/dL Questions 1. What does an elevated serum blood urea nitrogen (BUN) suggest? 2. What does an elevated creatinine suggest? 3. What is the clinical significance of the GFR and the urea nitrogen/creatinine ratio?

A 35-year-old man (height 67 inches, weight 73.3 kg) with known chronic renal disease for 6 months has blood drawn for serum creatinine and urea tests. Urine is collected for a 24-hour quantitative creatinine test; the total volume of urine collected is 1139 mL. The following laboratory results are obtained for the testing done: Urine creatinine: 56 mg/dL Serum creatinine: 9.6 mg/dL Serum urea: 75 mg/dL Questions 1. What does an elevated serum blood urea nitrogen (BUN) suggest? 2. What does an elevated creatinine suggest? 3. What is the clinical significance of the GFR and the urea nitrogen/creatinine ratio?