Need help choosing the right code?
Ask CasePilot about procedures, modifiers, bundling, and coding guidance.
Try CasePilot© Copyright 2026 American Medical Association. All rights reserved.
The CPT® Code 84425 refers to a laboratory test that measures the levels of thiamine, also known as Vitamin B-1, in the blood. Thiamine is a vital nutrient that plays a crucial role in the proper functioning of muscles and nerves, as well as in the metabolic processes that convert carbohydrates into energy. This test is particularly important in diagnosing conditions associated with thiamine deficiency, which can occur due to various factors, including chronic alcohol abuse and certain medical conditions. Decreased thiamine levels are commonly associated with several health issues, such as beriberi, Korsakoff's psychosis, Wernicke's encephalopathy, and Wernicke-Korsakoff syndrome. The testing process involves obtaining a blood sample through venipuncture, which is a separate reportable procedure. The laboratory utilizes quantitative high-performance liquid chromatography (HPLC) to analyze the plasma for total thiamine, thiamine, and thiamine monophosphate, while whole blood is tested for thiamine diphosphate using the same advanced HPLC technique. This comprehensive testing approach ensures accurate measurement of thiamine levels, aiding in the diagnosis and management of related health conditions.
© Copyright 2026 Coding Ahead. All rights reserved.
The thiamine (Vitamin B-1) blood test, represented by CPT® Code 84425, is indicated for the evaluation of thiamine levels in patients who may be at risk for deficiency. The following conditions and symptoms warrant this testing:
The procedure for testing thiamine levels involves several key steps to ensure accurate results. First, a qualified healthcare professional performs venipuncture to obtain a blood sample from the patient. This step is crucial as it allows for the collection of plasma and whole blood necessary for the subsequent analysis. The blood sample is then processed in a laboratory setting. The plasma is subjected to quantitative high-performance liquid chromatography (HPLC) to measure total thiamine, thiamine, and thiamine monophosphate levels. This sophisticated analytical technique provides precise quantification of these forms of thiamine. Concurrently, the whole blood sample is analyzed using the same HPLC method to determine the levels of thiamine diphosphate, the active form of thiamine in the body. The results from these tests are then compiled and interpreted by healthcare professionals to assess the patient's thiamine status and guide further clinical decisions.
After the blood sample has been collected and sent for analysis, there are generally no specific post-procedure care requirements for the patient. However, it is advisable for patients to remain hydrated and to follow any additional instructions provided by their healthcare provider. The results of the thiamine level test will typically be available within a few days, and healthcare professionals will discuss the findings with the patient, including any necessary follow-up actions or treatments based on the results. If thiamine deficiency is confirmed, appropriate dietary recommendations or supplementation may be initiated to address the deficiency and prevent associated health complications.
| Short Descr | ASSAY OF VITAMIN B-1 | Medium Descr | ASSAY OF THIAMINE-VITAMIN B-1 | Long Descr | Thiamine (Vitamin B-1) | 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. | GA | Waiver of liability statement issued as required by payer policy, individual case | 77 | Repeat procedure by another physician or other qualified health care professional: it may be necessary to indicate that a basic procedure or service was repeated by another physician or other qualified health care professional subsequent to the original procedure or service. this circumstance may be reported by adding modifier 77 to the repeated procedure or service. note: this modifier should not be appended to an e/m service. | GZ | Item or service expected to be denied as not reasonable and necessary | 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. | 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. | GW | Service not related to the hospice patient's terminal condition | 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. | GV | Attending physician not employed or paid under arrangement by the patient's hospice provider | GY | Item or service statutorily excluded, does not meet the definition of any medicare benefit or, for non-medicare insurers, is not a contract benefit | QJ | Services/items provided to a prisoner or patient in state or local custody, however the state or local government, as applicable, meets the requirements in 42 cfr 411.4 (b) | XE | Separate encounter, a service that is distinct because it occurred during a separate encounter | XS | Separate structure, a service that is distinct because it was performed on a separate organ/structure | XU | Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service |
|
Date
|
Action
|
Notes
|
|---|---|---|
| 2013-01-01 | Changed | Medium Descriptor changed. |
| Pre-1990 | Added | Code added. |
Get instant expert-level medical coding assistance.