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Official Description

Phosphohexose isomerase

© Copyright 2026 American Medical Association. All rights reserved.

Common Language Description

Phosphohexose isomerase, also known as glucose-6-phosphate isomerase, is a crucial enzyme involved in the metabolic pathway of glycolysis. This enzyme facilitates the isomerization process, converting glucose-6-phosphate into fructose-6-phosphate, which is a key step in the energy production pathway of cells. The enzyme is encoded by the GPI gene, and its proper function is essential for maintaining normal metabolic processes. Deficiencies or defects in the GPI gene can lead to significant health issues, including nonspherocytic hemolytic anemia, a condition characterized by the destruction of red blood cells, and in severe cases, can result in hydrops fetalis, a serious condition in fetuses marked by an abnormal accumulation of fluid. Understanding the role of phosphohexose isomerase is vital for diagnosing and managing related metabolic disorders.

© Copyright 2026 Coding Ahead. All rights reserved.

1. Indications

The procedure associated with the measurement of phosphohexose isomerase is indicated for the evaluation of specific metabolic disorders. The following conditions may warrant testing:

  • Nonspherocytic Hemolytic Anemia - This condition is characterized by the premature destruction of red blood cells that are not spherically shaped, often linked to enzyme deficiencies.
  • Hydrops Fetalis - A severe condition in fetuses that involves the accumulation of fluid in body cavities, which can be associated with genetic enzyme deficiencies.

2. Procedure

The procedure for measuring phosphohexose isomerase involves several key steps to ensure accurate assessment of enzyme activity. Each step is critical for obtaining reliable results.

  • Step 1: Sample Collection - A blood sample is collected from the patient, typically through venipuncture. This sample serves as the basis for enzyme activity analysis.
  • Step 2: Sample Preparation - The collected blood sample is processed to isolate the plasma or serum, which contains the enzymes necessary for testing. This may involve centrifugation to separate the components of the blood.
  • Step 3: Enzyme Activity Measurement - The enzyme activity of phosphohexose isomerase is measured using specific biochemical assays. These assays typically involve the addition of substrates and monitoring the conversion process, which is indicative of enzyme function.
  • Step 4: Data Analysis - The results from the enzyme activity measurement are analyzed and compared to normal reference ranges to determine if there is a deficiency or abnormality present.

3. Post-Procedure

After the procedure, the patient may be advised to follow up with their healthcare provider to discuss the results of the enzyme activity test. If a deficiency is detected, further diagnostic testing may be necessary to confirm the diagnosis and assess the severity of the condition. Management strategies may include monitoring, lifestyle modifications, or specific treatments depending on the underlying cause of the enzyme deficiency. It is important for patients to understand the implications of their test results and to engage in discussions regarding potential next steps in their care.

Short Descr ASSAY PHOSPHOHEXOSE ENZYMES
Medium Descr ASSAY OF PHOSPHOHEXOSE ISOMERASE
Long Descr Phosphohexose isomerase
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.
91 Repeat clinical diagnostic laboratory test: in the course of treatment of the patient, it may be necessary to repeat the same laboratory test on the same day to obtain subsequent (multiple) test results. under these circumstances, the laboratory test performed can be identified by its usual procedure number and the addition of modifier 91. note: this modifier may not be used when tests are rerun to confirm initial results; due to testing problems with specimens or equipment; or for any other reason when a normal, one-time, reportable result is all that is required. this modifier may not be used when other code(s) describe a series of test results (eg, glucose tolerance tests, evocative/suppression testing). this modifier may only be used for laboratory test(s) performed more than once on the same day on the same patient.
Date
Action
Notes
2013-01-01 Changed Medium Descriptor changed.
Pre-1990 Added Code added.
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Description
Code
Description
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