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Official Description

Phosphatase, alkaline; heat stable (total not included)

© Copyright 2026 American Medical Association. All rights reserved.

Common Language Description

The CPT® Code 84078 refers to a laboratory test that measures the levels of heat stable alkaline phosphatase (ALP) in a blood sample. Alkaline phosphatase is an important hydrolase enzyme that plays a critical role in the removal of phosphate groups from various molecules. This enzyme is predominantly found in several tissues, including the liver, bile ducts, kidneys, bones, and placenta. The measurement of alkaline phosphatase levels is significant in diagnosing and monitoring various medical conditions. Elevated levels of ALP may indicate potential health issues such as bile duct obstruction, Paget's disease, and certain types of tumors known as seminomas. Conversely, decreased levels of alkaline phosphatase can be associated with conditions such as hypophosphatasia, Wilson's disease, specific types of anemia or leukemia, and other health factors including postmenopausal estrogen therapy for osteoporosis, oral contraceptive use, cardiac surgery recovery in men, malnutrition, hypothyroidism, and certain genetic disorders in children like achondroplasia and cretinism. The test is performed on serum or plasma obtained through a venipuncture, which is a separate procedure that must be reported independently. The methodology used for this test involves quantitative enzymatic techniques, specifically designed to measure the heat stable fraction of alkaline phosphatase, which includes the placental alkaline phosphatase isoenzyme, known for its stability under heat conditions.

© Copyright 2026 Coding Ahead. All rights reserved.

1. Indications

The alkaline phosphatase heat stable test (CPT® Code 84078) is indicated for the evaluation of various medical conditions associated with abnormal alkaline phosphatase levels. The following conditions may warrant this test:

  • Bile Duct Obstruction - Elevated alkaline phosphatase levels may indicate an obstruction in the bile ducts, which can lead to liver dysfunction.
  • Paget's Disease - This condition, characterized by abnormal bone remodeling, may result in increased levels of alkaline phosphatase.
  • Seminomas - Certain tumors, particularly seminomas, can cause elevated alkaline phosphatase levels, making this test useful in their diagnosis and monitoring.
  • Hypophosphatasia - Decreased levels of alkaline phosphatase may be observed in this genetic disorder, which affects bone mineralization.
  • Wilson's Disease - This genetic disorder that leads to copper accumulation in the body may also result in lower alkaline phosphatase levels.
  • Anemia/Leukemia - Certain types of these blood disorders can affect alkaline phosphatase levels, necessitating testing.
  • Postmenopausal Women on Estrogen Therapy - Women undergoing estrogen therapy for osteoporosis may exhibit decreased alkaline phosphatase levels.
  • Oral Contraceptive Use - Women taking oral contraceptives may also show decreased levels of alkaline phosphatase.
  • Men Following Cardiac Surgery - Post-surgical recovery in men may lead to lower alkaline phosphatase levels.
  • Malnutrition or Hypothyroidism - Both conditions can result in decreased alkaline phosphatase levels.
  • Children with Achondroplasia, Cretinism, or Severe Enteritis - These conditions may also be associated with lower alkaline phosphatase levels.

2. Procedure

The procedure for measuring heat stable alkaline phosphatase involves several key steps that ensure accurate results. First, a qualified healthcare professional performs a venipuncture to obtain a blood sample from the patient. This step is crucial as it provides the serum or plasma needed for testing. Once the blood sample is collected, it is processed in a laboratory setting. The serum or plasma is subjected to a quantitative enzymatic methodology specifically designed to measure the heat stable fraction of alkaline phosphatase. This method involves heat inactivation, which allows for the isolation of the heat stable alkaline phosphatase isoenzyme, particularly the placental alkaline phosphatase (ALPP or Regan isoenzyme). The laboratory technician carefully follows established protocols to ensure the accuracy and reliability of the test results. After the analysis is complete, the results are documented and made available for review by the healthcare provider, who will interpret the findings in the context of the patient's overall health and any presenting symptoms.

3. Post-Procedure

After the alkaline phosphatase heat stable test is performed, there are generally no specific post-procedure care requirements for the patient. However, it is important for the healthcare provider to inform the patient about potential minor side effects from the venipuncture, such as bruising or discomfort at the site of blood draw. Patients are typically advised to resume their normal activities immediately following the test. The results of the test will be reviewed by the healthcare provider, who may discuss the implications of the findings with the patient and determine if any further testing or treatment is necessary based on the results and the patient's clinical picture.

Short Descr ASSAY ALKALINE PHOSPHATASE
Medium Descr ASSAY OF PHOSPHATASE ALKALINE HEAT STABLE
Long Descr Phosphatase, alkaline; heat stable (total not included)
Status Code Statutory Exclusion (from MPFS, may be paid under other methodologies)
Global Days XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC) 9 - Not Applicable
Multiple Procedures (51) 9 - Concept does not apply.
Bilateral Surgery (50) 9 - Concept does not apply.
Physician Supervisions 09 - Concept does not apply.
Assistant Surgeon (80, 82) 9 - Concept does not apply.
Co-Surgeons (62) 9 - Concept does not apply.
Team Surgery (66) 9 - Concept does not apply.
Diagnostic Imaging Family 99 - Concept Does Not Apply
CLIA Waived (QW) No
APC Status Indicator Conditionally packaged laboratory tests
Type of Service (TOS) 5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS) T1H - Lab tests - other (non-Medicare fee schedule)
MUE 1
CCS Clinical Classification 233 - Laboratory - Chemistry and Hematology
90 Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number.
26 Professional component: certain procedures are a combination of a physician or other qualified health care professional component and a technical component. when the physician or other qualified health care professional component is reported separately, the service may be identified by adding modifier 26 to the usual procedure number.
Date
Action
Notes
2013-01-01 Changed Medium Descriptor changed.
Pre-1990 Added Code added.
Code
Description
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