What is the reference range for the amylase:creatinine clearance ratio (SCUA)?

• A. 1-5%
• B. 0-1%
• C. 5-10%
• D. 10-20%

Answer: (A)

The key idea is how amylase excretion in urine compares to that of creatinine, which mirrors kidney filtration. The amylase:creatinine clearance ratio (SCUA) shows how much urinary amylase is cleared relative to creatinine. In people with normal kidney function, this ratio is a small fraction of total clearance, typically around 1% to 5% of creatinine clearance. That’s why 1-5% is the best reflection of normal variability. Values within this range indicate normal processing of amylase; higher values can occur when serum amylase is elevated (as in pancreatitis) and the urinary clearance rises disproportionately, while very low values may point toward macroamylasemia where large complexes aren’t filtered well. The other ranges are not typical for a normal reference, making 1-5% the appropriate answer.