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PTD - 150

Test Directory -  Acetylcholine receptor antibodies

Synonyms

ACR, AChR Ab

Clinical Indications

ACR antibodies are indicated in investigation of suspected Myasthenia Gravis (MG) in which muscles tire or become fatigued very easily. Muscles around the eyes are commonly affected first (2 in 3 cases), causing drooping eyelids and double vision. Muscles around neck, face and throat are commonly affected causing difficulty in swallowing, speaking and chewing. Weakness in the arms, legs and other skeletal muscles may develop.

In chronic diseases such as Myasthenia Gravis, if antibodies are not positive on onset, it is worth retesting in 3-6 months if clinically indicated. Patients do sometimes become antibody positive within the first year. Once confirmed positive, it is not usual to monitor levels.

Request Form 

Combined Pathology Blood form (Yellow/Black or Blue for GP's)

Availability

Referred test: Analysed by Immunology, Oxford Hospital if specific criteria met.

Specific Criteria

Investigation of suspected myasthenia gravis.

Patient Preparation  

None required

Turnaround Time

2 to 3 weeks

Specimen

Serum

Volume

1 ml

Container


Yellow top (SST) tube

Causes for Rejection

Unlabelled sample, not meeting specific criteria for analysis. 

Reference Range

Negative

Interpretation

ACR antibodies are seen in over 80% of patients with MG, and are probably responsible for most of the symptoms; they are not seen in the rare congenital form of the disease. They may occur in ocular myasthenia, and penicillamine-induced myasthenia, but are not seen in healthy individuals.  
Antibody positive patients should also be checked for skeletal (striated) muscle antibodies: when both are positive, this is a consistent with myasthenia associated with thymoma.

Lab. Handling

Processing: Aliquot (MPA) and store at 4C in separating fridge (CB39), referred test rack.
Referral:
ACRAB and send or BPRO and save in separating freezer (CB40) at -20C, saved frozen rack.
 

Version 1.1 / May 2014                                                                                                           Approved by: Consultant Biochemist