Preferred Sample Type
Suitable Specimen Types
- Serum
- EDTA Plasma
Sample Processing in Laboratory
UsualSample Preparation
Centifruge and separate. 300 uL of sample either serum or EDTA plasma is necessary to allow duplicate analyses to be carried out if required. Grossly haemolysed or lipaemic samples are unsuitable for this assay.Turnaround Time
21 daysSample Stability
Samples are stored frozen until analysis is complete and subsequently stored in Immunology for 6 months.Acetylcholine receptor antibodies (ACRA)
General Information
Autoantibodies to the acetylcholine receptor (ACh RAb) are responsible for failure of the neuromuscular junction in myasthenia gravis, and measurement of the antibodies can be of considerable value in disease diagnosis.
As of 01/10/2021 this assay is performed on automated ELISA platform rather than by radioimmunoassay .
This assay has a stated sensitivity of 96% and a specificity of 97.1%
Patient Preparation
None
Notes
About 10% patients with myasthenia may have no detectable ACR abs.
Up to 40% of Patients with exclusively ocular myasthenia may have negative ACR abs.
In cases where ACR antibodies are negative and clinical presentation and suspicion of myesthenia remain high it is recommended that a repeat sample is sent and a request for ACR cluster antibodies by cell based assay is made.
Reference Range
<0.4 nmol/L = negative.
0.4 - 0.5 nmol/L = borderline
>0.5 nmol/L = positive.
Reference range provided by Kit manufacturer
Specifications
- EQA Scheme?: Yes
- EQA Status: UKNEQAS