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An Activated Protein C (APC) resistance assay is a specialized laboratory test designed to evaluate patients who have experienced unexplained venous thromboembolism (VTE). This assay is particularly focused on identifying a specific genetic mutation known as Factor V Leiden, which is a single point mutation in the Factor V gene. The presence of this mutation can significantly increase the risk of developing abnormal blood clots. The test involves comparing the patient's blood sample to a control sample that contains Factor V deficient plasma. By adding Activated Protein C to both samples, the assay assesses how the blood's clotting ability is affected. In a normal scenario, the addition of APC leads to a significant prolongation of the activated partial thromboplastin time (aPTT), indicating normal function. However, if the Factor V Leiden mutation is present, the prolongation will be less pronounced compared to the control, allowing for the determination of APC resistance. The results are quantified by calculating a ratio of the aPTT with APC to the aPTT without APC for both the patient and control samples, providing a clear indication of whether the mutation is present or absent.
© Copyright 2025 Coding Ahead. All rights reserved.
The Activated Protein C (APC) resistance assay is indicated for patients who present with unexplained venous thromboembolism (VTE). This condition may manifest as deep vein thrombosis (DVT) or pulmonary embolism (PE) without an obvious cause. The assay is particularly useful in identifying the presence of the Factor V Leiden mutation, which is a known risk factor for recurrent thrombotic events.
The procedure for conducting the Activated Protein C (APC) resistance assay involves several critical steps to ensure accurate results. Initially, a blood sample is drawn from the patient, which will be tested for APC resistance. This sample is then diluted appropriately to prepare it for analysis. Concurrently, a control specimen is prepared using Factor V deficient plasma, which serves as a benchmark for comparison. Once both specimens are ready, Activated Protein C is added to each sample. The next step involves measuring the activated partial thromboplastin time (aPTT) for both the patient sample and the control sample. In a normal scenario, the addition of APC should lead to a two-fold increase in aPTT for the control sample, indicating normal clotting function. However, if the patient has the Factor V Leiden mutation, the aPTT will still be prolonged but to a lesser extent than the control. The results are then normalized by calculating the ratio of aPTT with APC to aPTT without APC for both the patient and control specimens. This ratio is crucial for determining the presence of the mutation; if the patient’s ratio is significantly lower than that of the control, it indicates the presence of the Factor V mutation.
After the Activated Protein C (APC) resistance assay is completed, the results are analyzed and interpreted by a qualified healthcare professional. Patients may not require any specific post-procedure care, as the test is performed on a blood sample and does not involve invasive procedures. However, it is essential for healthcare providers to discuss the results with the patient, especially if the test indicates the presence of the Factor V Leiden mutation. This discussion may include recommendations for monitoring, potential lifestyle changes, or further testing to assess the risk of future thrombotic events. Additionally, patients with a positive result may be advised on preventive measures to reduce the risk of VTE.
| Short Descr | ASSAY ACTIVATED PROTEIN C | Medium Descr | ACTIVATED PROTEIN C APC RESISTANCE ASSAY | Long Descr | Activated Protein C (APC) resistance assay | 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 | 2 | 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. | 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. | 59 | Distinct procedural service: under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-e/m services performed on the same day. modifier 59 is used to identify procedures/services, other than e/m services, that are not normally reported together, but are appropriate under the circumstances. documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. however, when another already established modifier is appropriate it should be used rather than modifier 59. only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. note: modifier 59 should not be appended to an e/m service. to report a separate and distinct e/m service with a non-e/m service performed on the same date, see modifier 25. | GA | Waiver of liability statement issued as required by payer policy, individual case | GZ | Item or service expected to be denied as not reasonable and necessary | Q1 | Routine clinical service provided in a clinical research study that is in an approved clinical research study | Q4 | Service for ordering/referring physician qualifies as a service exemption |
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| 2001-01-01 | Added | First appearance in code book in 2001. |
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