Test Name: Acetylcholine Receptor (AChR) Binding Antibody

Method: Enzyme Immunoassay

Test Principle: This test measures the presence of antibodies that bind to the acetylcholine receptor (AChR) on the surface of muscle cells. These antibodies are commonly found in autoimmune diseases such as myasthenia gravis, where they interfere with the normal functioning of the AChR.

Metabolism or Outline: The test involves incubating the patient’s serum with AChR-coated wells. If the patient has antibodies against AChR, they will bind to the AChR in the wells. After washing away unbound proteins, an enzyme-labeled antibody is added, which will bind to any patient antibodies that are already bound to the AChR. The enzyme’s activity is then measured, and the intensity is proportional to the amount of patient antibodies present.

Primary Sample(s) Type, Container color code, and Quantity required: Serum, collected in a Red Capped Vacutainer or Yellow Cap Vacutainer. A minimum of 4ml of serum is required.

Patient Preparation Instructions: No specific patient preparation is required for this test.

Sample stability at Room temperature, Refrigerated, and Frozen: The serum sample is stable at room temperature for up to 8 hours, refrigerated for up to 1 week, and frozen for up to 4 weeks.

Biological reference range, gender, and age-specific if applicable: The reference range for this test is as follows: Negative: 0.0-0.4 nmol/L, Positive: 0.5 nmol/L or greater. There are no gender or age-specific variations for this test.

Units and alternate units and their conversions: The unit for this test is nanomoles per liter (nmol/L).

Increased in: The presence of elevated levels of Acetylcholine Receptor (AChR) Binding Antibodies is associated with autoimmune conditions such as myasthenia gravis.

Decreased in: A decrease in Acetylcholine Receptor (AChR) Binding Antibodies is not relevant for this test.

Other related tests: Other related tests that may be ordered in conjunction with Acetylcholine Receptor (AChR) Binding Antibody include Acetylcholine Receptor (AChR) Modulating Antibody and Muscle-Specific Kinase (MuSK) Antibody.

Which organs are connected to the test and how: This test is primarily used to evaluate neuromuscular disorders, specifically myasthenia gravis, which affects the neuromuscular junctions.

Calculations & equations, if any: No specific calculations or equations are involved in the interpretation of this test. The result is reported as a qualitative result (positive or negative) or a quantitative result (nmol/L).

Reference: Li Y, Peng Y, Yang H. Serological diagnosis of myasthenia gravis and its clinical significance. Ann Transl Med. 2023 Apr 15;11(7):290. doi: 10.21037/atm-19-363. Epub 2019 Sep 29. PMID: 37090043; PMCID: PMC10116419.