Correct!
5. All of the above
TSH - approximately 30% of affected myasthenia gravis patients have a concomitant thyroid disease.
EMG - A very sensitive (97-99%) test, but with low specificity (decremented response is also seen in Lambert-Eaton myasthenic syndromes, botulism toxin).
Autoantibodies – Autoantibodies against the postsynaptic acetylcholine receptor (AChR-Abs) or against muscle-specific tyrosine kinase receptors (MuSK) occur in most patients. AChR-Abs come in 3 types: binding, blocking or modulating, with binding being the most sensitive (present in 80-90 % of patient s with generalized disease.) Binding AChR-Abs rarely seen in other disorders: primary biliary cirrhosis, SLE, thymoma without myasthenia. MuSK antibodies should be tested when AChR antibodies are negative, particularly among patients with prominent bulbar muscle weakness.
CT of chest - Approximately 75% of affected patients have some sort of thymus abnormalities (hyperplasia, thymoma, etc); other associations include small cell cancer of the lung, breast cancer, Hodgkin lymphoma.
What are management options for myasthenia crisis? (Click on the correct answer to proceed to the next panel).