CPT® Code 86042

Official Description

Acetylcholine receptor (AChR); blocking antibody

Common Language Description

Acetylcholine receptor (AChR) antibodies are specific proteins that can be found in the bloodstream of individuals diagnosed with myasthenia gravis (MG), a rare neuromuscular disorder characterized by significant muscle weakness and fatigue. Myasthenia gravis can manifest in two primary forms: ocular myasthenia gravis, which primarily affects the muscles around the eyes, leading to symptoms such as drooping eyelids, double vision, and weakness in eye muscle function; and generalized myasthenia gravis, which can involve weakness in various muscle groups, including those in the neck, throat, and respiratory system. Patients with generalized MG may experience difficulties with chewing, swallowing, speaking, and may even face challenges in walking or breathing. It is noteworthy that approximately 15% of individuals with MG may only exhibit ocular symptoms. The presence of AChR antibodies disrupts the normal communication between nerves and muscles by interfering with the action of acetylcholine, a critical neurotransmitter responsible for transmitting signals from nerves to muscles. Specifically, blocking antibodies hinder acetylcholine from effectively binding to its receptors on muscle cells, which results in diminished muscle contraction and function. To diagnose the presence of these antibodies, a venous blood sample is collected, and semi-quantitative flow cytometry is employed for testing. A positive result for AChR antibodies can confirm a diagnosis of MG in symptomatic patients; however, it is important to note that elevated antibody levels may also be observed in individuals with thymoma, a type of tumor associated with the thymus gland. In clinical practice, it is estimated that 10%-15% of patients with MG may not test positive for AChR antibodies, necessitating further testing for other types of antibodies, such as muscle-specific kinase (MuSK) antibodies. A blocking antibody result exceeding 42% is interpreted as positive, while results ranging from 26% to 41% are deemed indeterminate, indicating the need for additional testing for modulating antibodies. Blocking antibodies represent the second most prevalent type of AChR antibody found in patients with generalized myasthenia gravis.

1. Indications

The testing for acetylcholine receptor (AChR) blocking antibodies is indicated in the following scenarios:

Myasthenia Gravis Diagnosis The presence of AChR blocking antibodies is primarily tested to confirm a diagnosis of myasthenia gravis (MG) in patients exhibiting symptoms consistent with the condition.
Ocular Symptoms Patients presenting with ocular symptoms such as drooping eyelids and double vision may be tested for AChR antibodies to determine the underlying cause of these manifestations.
Generalized Symptoms Individuals showing generalized symptoms, including weakness in neck muscles, difficulty with chewing, swallowing, or speaking, may also undergo testing for AChR antibodies to support a diagnosis of generalized MG.
Thymoma Evaluation Elevated levels of AChR antibodies may be evaluated in patients with thymoma, as these antibodies can also be present in this condition.
Negative AChR Antibody Testing In cases where patients exhibit symptoms of MG but test negative for AChR antibodies, further testing for other antibodies, such as muscle-specific kinase (MuSK) antibodies, may be warranted.

2. Procedure

The procedure for testing AChR blocking antibodies involves several key steps:

Blood Sample Collection A sample of venous blood is drawn from the patient, which serves as the specimen for testing. This step is crucial as it provides the necessary biological material to analyze the presence of AChR antibodies.
Semi-Quantitative Flow Cytometry The collected blood sample is subjected to semi-quantitative flow cytometry, a laboratory technique that allows for the detection and quantification of specific antibodies present in the blood. This method enables the identification of AChR blocking antibodies and provides a measure of their concentration.
Result Interpretation The results of the flow cytometry test are interpreted based on established thresholds. A blocking antibody result greater than 42% is considered positive, indicating the presence of AChR blocking antibodies. Results between 26% and 41% are classified as indeterminate, suggesting the need for further testing for modulating antibodies to clarify the diagnosis.

3. Post-Procedure

After the procedure, patients may not require any specific post-procedure care, as the blood draw is a routine procedure with minimal risk. However, it is essential for healthcare providers to discuss the test results with the patient once they are available. A positive test result can confirm a diagnosis of myasthenia gravis in symptomatic individuals, while indeterminate results may necessitate additional testing for other antibodies. Patients should be informed about the implications of their test results and any further steps that may be required for diagnosis or treatment. Regular follow-up appointments may be necessary to monitor symptoms and adjust treatment plans accordingly.

Short Descr	ACETYLCHOLN RCPTR BLCKG ANTB
Medium Descr	ACETYLCHOLINE RECEPTOR BLOCKING ANTIBODY
Long Descr	Acetylcholine receptor (AChR); blocking antibody
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)	none
MUE	1

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.
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.
GZ	Item or service expected to be denied as not reasonable and necessary