Which laboratory formula, when yielding a value greater than 5%, supports acute pancreatitis over other causes of hyperamylasemia?

• A (Serum amylase / serum lipase) multiplied by 100
• B (Serum amylase / serum creatinine) divided by urinary amylase, expressed as percent
• C (Urinary amylase / urinary creatinine) divided by (serum amylase / serum creatinine), expressed as percent ✓
• D (Urinary lipase / urinary amylase) multiplied by 100

Explanation

The amylase to creatinine clearance ratio is calculated as (urine amylase / serum amylase) divided by (urine creatinine / serum creatinine), times 100. Values above 5 percent favour acute pancreatitis, where tubular reabsorption of amylase is impaired, versus normal clearance of 1 to 4 percent seen in salivary hyperamylasemia and macroamylasemia. This ratio was historically useful to separate pancreatic from non-pancreatic sources before reliable isoenzyme assays became routine.

Reference: Harper's Illustrated Biochemistry, 31st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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