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Test ID: ALP Alkaline Phosphatase, Serum

Reporting Name

Alkaline Phosphatase, S

Useful For

Diagnosing and monitoring treatment of liver, bone, intestinal, and parathyroid diseases

Clinical Information

Alkaline phosphatase in serum consists of 4 structural genotypes: liver-bone-kidney, intestinal, and placental types, and the variant from the germ cells. It is found in osteoblasts, hepatocytes, leukocytes, the kidneys, spleen, placenta, prostate, and the small intestine. The liver-bone-kidney type is particularly important.


A rise in the alkaline phosphatase occurs with all forms of cholestasis, particularly with obstructive jaundice. It is also elevated in diseases of the skeletal system, such as Paget disease, hyperparathyroidism, rickets, and osteomalacia, as well as with fractures and malignant tumors. A considerable rise in the alkaline phosphatase activity is sometimes seen in children and teenagers. It is caused by increased osteoblast activity following accelerated bone growth.


Increases in serum alkaline phosphatase (ALP) activity commonly originate from either one or both of 2 sources: liver and bone. Consequently, serum ALP measurements are of particular interest in the investigation of 2 groups of conditions: hepatobiliary disease and bone disease associated with increased osteoblastic activity.


Serum ALP was the first enzyme to be used for the investigation of hepatic disease. The response of the liver to any form of biliary tree obstruction induces the synthesis of ALP by hepatocytes. The newly formed coenzyme is released from the cell membrane by the action of bile salts and enters the circulation to increase the enzyme activity in serum. Increase tends to be more notable (greater than 4-fold the upper reference value [URV]) in extrahepatic obstruction (eg, by stone, by cancer of the head of the pancreas) than in intrahepatic obstruction and is greater the more complete the obstruction. Serum enzyme activities may reach 10 to 12 times the URV and usually return to baseline on surgical removal of the obstruction. A similar increase is seen in patients with advanced primary liver cancer or widespread secondary hepatic metastases. ALP increase (greater than 2-fold the URV) can predict transplant-free survival rates of patients with primary biliary cirrhosis.


Liver diseases that principally affect parenchymal cells, such as infectious hepatitis, typically show only moderately (less than 3-fold) increased or even normal serum ALP activities. Increases may also be seen as a consequence of a reaction to drug therapy, and ALT/ALP-based criteria to discriminate the type of liver injury in drug-induced hepatic toxicity have been recommended. Intestinal ALP isoenzyme, an asialoglycoprotein normally cleared by the hepatic asialoglycoprotein receptors, is often increased in patients with liver cirrhosis.

Report Available

Same day/1 to 2 days

Day(s) Performed

Monday through Sunday

Clinical Reference

1. Panteghini M, Bais R: Serum enzymes. In: Rifai N, Horvath AR, Wittwer C, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Elsevier; 2018:404-434

2. Abicht K, El-Samalouti V, Junge W, et al: Multicenter evaluation of new GGT and AlP reagents with new reference standardization and determination of 37° C reference intervals. Clin Chem Lab Med. 2001;39(Special Suppl):S346

3. Estey MP, Cohen AH, Colantonio DA, et al: CLSI-based transference of the CALIPER database of pediatric reference intervals from Abbott to Beckman, Ortho, Roche and Siemens Clinical Chemistry Assays: Direct validation using reference samples from the CALIPER cohort. Clin Biochem. 2013;46:1197-1219

4. Lammers WJ, van Buuren HR, Hirschfield GM, et al: Levels of alkaline phosphatase and bilirubin are surrogate end points of outcomes of patients with primary biliary cirrhosis: An international follow-up study. Gastroenterology. 2014; 147: pp. 1338-1349

Method Name


Specimen Type


Necessary Information

Patient's age and sex are required.

Specimen Required

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Serum gel tubes should be centrifuged within 2 hours of collection.

2. Red-top tubes should be centrifuged and aliquoted within 2 hours of collection.

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Frozen (preferred) 60 days
  Ambient  7 days
  Refrigerated  7 days

Reference Values


0-14 days: 83-248 U/L

15 days-<1 year: 122-469 U/L

1-<10 years: 142-335 U/L

10-<13 years: 129-417 U/L

13-<15 years: 116-468 U/L

15-<17 years: 82-331 U/L

17-<19 years: 55-149 U/L

≥19 years: 40-129 U/L



0-14 days: 83-248 U/L

15 days-<1 year: 122-469 U/L

1-<10 years: 142-335 U/L

10-<13 years: 129-417 U/L

13-<15 years: 57-254 U/L

15-<17 years: 50-117 U/L

≥17 years: 35-104 U/L

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
ALP Alkaline Phosphatase, S 6768-6


Result ID Test Result Name Result LOINC Value
ALP Alkaline Phosphatase, S 6768-6
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