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Official Description

Leukocyte histamine release test (LHR)

© Copyright 2026 American Medical Association. All rights reserved.

Common Language Description

The Leukocyte Histamine Release Test (LHR), identified by CPT® Code 86343, is a diagnostic procedure that evaluates the immune response of peripheral blood leukocytes to specific allergens. This test quantifies the histamine released from these white blood cells when exposed to various concentrations of an allergen extract. Histamine is a chemical involved in local immune responses, and its release indicates a hypersensitivity reaction to the allergen. In individuals with an allergy, the leukocytes will release histamine upon exposure to the allergen, which can be measured in the laboratory. It is important to note that the test is limited in that only a select number of allergens can be tested simultaneously within a single blood sample. Additionally, there is inherent variability in the measurement of histamine levels, which can affect the reliability of the results. Due to these factors, the LHR test may be regarded as investigational by many insurance policies, reflecting the ongoing debate regarding its clinical utility and standardization in allergy testing.

© Copyright 2026 Coding Ahead. All rights reserved.

1. Indications

The Leukocyte Histamine Release Test (LHR) is indicated for the evaluation of hypersensitivity reactions to specific allergens. This test is particularly useful in cases where traditional allergy testing methods may not provide conclusive results. The following conditions may warrant the use of this test:

  • Allergic Rhinitis - Patients experiencing symptoms of nasal congestion, sneezing, and itching due to environmental allergens.
  • Asthma - Individuals with asthma may undergo this test to identify specific allergens that could trigger their respiratory symptoms.
  • Atopic Dermatitis - Patients with eczema or other skin conditions may be tested to determine if allergens are contributing to their symptoms.
  • Food Allergies - The test may be utilized to assess hypersensitivity to certain food items when other testing methods are inconclusive.

2. Procedure

The procedure for conducting the Leukocyte Histamine Release Test involves several key steps to ensure accurate measurement of histamine levels in response to allergens. The following outlines the procedural steps:

  • Step 1: Sample Collection - A blood sample is drawn from the patient, typically from a vein in the arm. This sample will contain the peripheral blood leukocytes necessary for the test.
  • Step 2: Allergen Exposure - The collected blood sample is exposed to varying concentrations of specific allergen extracts. This exposure is crucial as it simulates the immune response that occurs in the presence of allergens.
  • Step 3: Incubation - The blood sample is incubated for a specified period, allowing time for the leukocytes to react to the allergens. During this time, if the patient has a hypersensitivity to the allergen, histamine will be released from the leukocytes.
  • Step 4: Measurement of Histamine Levels - After incubation, the amount of histamine released is measured using laboratory techniques. This quantification provides insight into the degree of hypersensitivity the patient has to the tested allergens.

3. Post-Procedure

After the Leukocyte Histamine Release Test is completed, the patient may be monitored briefly to ensure there are no immediate adverse reactions to the allergens used during the test. The results of the test will be analyzed and interpreted by a qualified healthcare professional, who will discuss the findings with the patient. Depending on the results, further testing or treatment options may be recommended. It is important for patients to follow up with their healthcare provider to understand the implications of the test results and to develop an appropriate management plan for their allergies.

Short Descr LEUKOCYTE HISTAMINE RELEASE
Medium Descr LEUKOCYTE HISTAMINE RELEASE TEST LHR
Long Descr Leukocyte histamine release test (LHR)
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 235 - Other Laboratory
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.
GW Service not related to the hospice patient's terminal condition
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
GA Waiver of liability statement issued as required by payer policy, individual case
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.
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