Step 1: Understanding BUN and plasma creatinine.
Blood Urea Nitrogen (BUN) and plasma creatinine are renal filtration indicators of kidney function. Elevated levels in either or both suggest compromised kidney function.
Step 2: Rationale for plasma creatinine.
Plasma creatinine, a product of muscle metabolism, is filtered by the kidneys. Elevated levels signify inefficient kidney filtration.
Step 3: Examination of alternative tests.
- (A) Plasma Albumin: Reflects blood protein levels, not kidney function.
- (B) Plasma Bilirubin: A byproduct of red blood cell degradation, not directly indicative of kidney function.
- (C) Plasma Biliverdin: A precursor to bilirubin, unrelated to kidney function.
Step 4: Conclusion.
Consequently, plasma creatinine is the additional test used to evaluate kidney function.