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

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

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.