Alkaline Phosphatase Isoenzymes

CPT: 84075 (total); 84080 (isoenzymes)
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Test Details

Synonyms

  • Fractionated Alkaline Phosphatase
  • Kasahara Isoenzymes
  • Nag Ao Isoenzymes
  • Regan Isoenzymes

Test Includes

Relative percentages of liver, bone, and intestinal alkaline phosphatase isoenzymes and total alkaline phosphatase

Use

Evaluate the contribution of the isoforms of ALP from liver, bone, and bowel to total ALP; investigate elevations of ALP to determine the tissue of origin

Methodology

Electrophoresis

Contraindications

Normal total alkaline phosphatase level

Reference Interval

See table.

LIVER FRACTION

Age

(Male)

Percentage Range

(Male)

0 to 6 m

Not established

7 m to 5 y

3% to 50%

6 to 17 y

3% to 31%

18 to 100 y

13% to 88%

Age

(Female)

Percentage Range

(Female)

0 to 6 m

Not established

7 m to 5 y

3% to 51%

6 to 12 y

2% to 25%

13 to 100 y

18% to 85%

BONE FRACTION

Age

(Male)

Percentage Range

(Male)

0 to 6 m

Not established

7 m to 5 y

48% to 97%

6 to 17 y

67% to 97%

18 to 100 y

12% to 68%

Age

(Female)

Percentage Range

(Female)

0 to 6 m

Not established

7 m to 5 y

48% to 97%

6 to 12 y

69% to 97%

13 to 100 y

14% to 68%

INTESTINE FRACTION

Age

(Male)

Percentage Range

(Male)

0 to 30 d

Not established

1 m to 17 y

0% to 8%

18 to 100 y

0% to 18%

Age

(Female)

Percentage Range

(Female)

0 to 30 d

Not established

1 m to 17 y

0% to 8%

18 to 100 y

0% to 18%

Additional Information

Liver is the isoenzyme most frequently elevated when total ALP levels are elevated. Liver ALP increases in the blood early in liver disease before most other liver function tests show abnormalities. The wide group of conditions leading to increased liver ALP include acute hepatitis, cirrhosis, fatty liver, drug-induced liver disease, obstruction of biliary flow by carcinoma at the head of the pancreas, bile duct stricture, primary biliary cirrhosis, and metastatic carcinoma of the liver.

Bone isoenzyme is elevated as a result of increased osteoblastic activity. This isoenzyme is normally elevated in growing children and adults over the age of 50. The highest total ALP values have been attributed to an increased bone isoenzyme level due to Paget disease or renal rickets. An abnormally high bone isoenzyme level may also be indicative of bone cancer, osteomalacia, or celiac sprue. A decreased bone ALP in children may be attributed to cretinism or to hypophosphatasia.

Intestinal alkaline phosphatase is seen normally in the serum of subjects who have B or O blood types, especially after a fatty meal. Pathologically, the band may be present in perforation of the bowel, ulcerative disease of the intestine, and faintly in liver cirrhosis. Acute infarction of the intestine will cause a release of intestinal ALP from the mucosa. Large erosive or ulcerative lesions of the stomach, duodenum or other small intestinal areas, or colon may result in an elevation of the serum ALP level. The small intestinal lesions associated with malabsorption are associated with an elevation of the serum intestinal ALP level only if there is an erosive or ulcerative mucosal lesion.

Specimen Requirements

Specimen

Serum

Volume

2 mL

Minimum Volume

0.5 mL

Container

Red-top tube or gel-barrier tube

Patient Preparation

Patient should be fasting overnight. Patients who have B or O blood group and are secretors may have an elevated ALP about two hours after a fatty meal.

Collection

Separate serum from cells as soon as possible after the blood is allowed to clot.

Storage Instructions

Refrigerate serum at 2°C to 8°C as soon as possible after collection.

Stability Requirements

Temperature

Period

Room temperature

7 days

Refrigerated

7 days

Frozen

7 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Patient not fasting; hemolysis; citrate, oxalate, or EDTA anticoagulated plasma

Clinical Information

Special Instructions

State patient's age and sex on the test request form.

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
001612 Alk Phos Isoenzyme 001107 Alkaline Phosphatase, S IU/L 6768-6
001612 Alk Phos Isoenzyme 016239 Liver Fraction: % 15015-1
001612 Alk Phos Isoenzyme 016240 Bone Fraction: % 15013-6
001612 Alk Phos Isoenzyme 016241 Intestinal Frac.: % 15014-4

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