Alkaline Phosphatase
Code:8047
| Includes | Alkaline phosphatase |
|---|
Analysis details
Methodology
- Colorimetric method
- Kinetic colorimetric method
Expected Turnaround Time
1 day
Special Instructions
- Do not eat or drink anything except water for 12 hours before the blood draw.
- Avoid vigorous activity and emotional stress for at least 30 minutes prior to collection.
- Do not smoke during the 30 minutes before phlebotomy.
How to use
The alkaline phosphatase (ALP, alk phos) test assists in detecting and characterizing hepatobiliary disease with cholestasis, including extrahepatic biliary obstruction such as gallstones or pancreatic neoplasm, often in conjunction with gamma-glutamyltransferase. It supports evaluation when clinical or laboratory findings suggest impaired bile flow. It also aids assessment of conditions with increased osteoblastic activity, including physiologic growth, fracture healing, and metastatic involvement of bone. When ALP is elevated, repeat testing is used to monitor disease activity and therapeutic response.
Limitations
Alkaline phosphatase is expressed on hepatocytes and biliary epithelium and catalyzes dephosphorylation reactions; measured serum activity reflects enzyme released from cells rather than an in vivo circulating function. Bile produced by hepatocytes flows through canaliculi into the hepatic ducts and common bile duct; interruption of this flow leads to pronounced ALP elevations consistent with cholestasis. In the skeleton, ALP is produced by osteoblasts and parallels bone formation, with physiologically higher values in children and during fracture repair. Placental and intestinal isoenzymes can also contribute to total ALP activity.
| Unit | U/L | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Reference interval |
| |||||||||
| Indications | Included in hepatic function panels for routine health screening and preoperative assessment., Workup of suspected hepatobiliary disease or cholestasis presenting with jaundice, right upper-quadrant pain, dark urine, pale stools, or pruritus., Assessment of nonspecific systemic complaints that may indicate liver disease, such as asthenia, fatigue, anorexia, nausea, or vomiting., Evaluation of bone disorders manifested by bone pain, skeletal deformity, or recurrent/pathologic fractures. |
Possible Causes of Abnormal Results
Increased levels
- acetaminophen
- allopurinol
- antibiotics
- aspirin
- childhood and adolescence
- pregnancy
- recent fracture
- specimen cooled after collection
Decreased levels
- oral contraceptives
Specimen Requirements
| Specimen | Serum |
|---|---|
| Container | Gold/Tiger Top (SST, Gel Separator) |
| Volume | 1 mL (min 0.7 mL) |
| Storage Instructions | Room temperature, Refrigerated, Frozen |