Amylase, Urine (Amylase/Creatinine Clearance Ratio [ALCR])

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Subject: Amylase, Urine (Amylase/Creatinine Clearance Ratio [ALCR])

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Definition

  • The ratio between amylase and creatinine in serum and urine. Also referred as fractional excreted of amylase. ALCR is calculated as:

  • Normal range:

    • Amylase urine: 1–17 U/hour

    • ALCR: 1–4%

Use

  • Differential diagnosis of pancreatitis

  • Diagnosis of pseudocyst of the pancreas, where the urine amylase may remain elevated for weeks after the serum amylase has returned to normal, after a bout of acute pancreatitis.

Interpretation

Increased In

  • Pancreatitis (>6%)

  • DKA

  • Renal insufficiency

  • Duodenal perforation

  • Large doses of corticosteroids

  • Pancreatic cancer

  • Myeloma and light chain disease

Decreased In

  • Macroamylasemia

Limitations

  • Macroamylasemia is characterized by high serum amylase but normal urine amylase. The ALCR remains useful for the diagnosis of macroamylasemia. In macroamylasemia, the clearance is very low.

 
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