Leucine aminopeptidase (LAP), an isoenzyme of alkaline phosphatase, is widely distributed in body tissues, with greatest concentrations found in hepatobiliary tissues, pancreas, and small intestine.

Elevated levels are associated with biliary obstruction resulting from gallstones and tumors, including those of the head of the pancreas, strictures, and atresia. Advanced pregnancy and therapy with drugs containing estrogen and progesterone also may raise LAP levels.

Note: Values may vary depending on the units of measure used by the laboratory performing the test.

• Advanced pregnancy and therapy with drugs containing estrogen and progesterone may falsely elevate levels.

• Elevated ALP of uncertain etiology:
  • Elevated levels support the diagnosis of hepatobiliary or pancreatic disease or both as the source of the elevated ALP.
  • Normal levels support the diagnosis of bone disease as the source of the elevated ALP.

Nursing Care Before the Procedure

Client preparation is the same as that for any test involving the collection of a peripheral blood sample (see Appendix I).

• Some laboratories require the client to fast from food for 8 hours before the test.

A venipuncture is performed and the sample collected in a red-topped tube. The sample should be handled gently to avoid hemolysis and transported promptly to the laboratory.

Nursing Care After the Procedure

Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample.

• Resume any food withheld before the test.