Fast Five Quiz: Myasthenia Gravis Workup

Richard Nowak, MD, MS


July 08, 2021

Figure 1. Myasthenia gravis (MG) is a condition involving voluntary muscles, most commonly of the eye, mouth, and throat. Normally, acetylcholine, a neurotransmitter (yellow) released by a neuron (turquoise), travels to the neurotransmitter receptors (green), leading to muscle contraction. MG is an autoimmune disease where there are fewer receptors than normal. The few existing receptors are blocked by antibodies (purple).

In contrast to anti-AChR antibody titers, data point to a correlation between anti-MuSK titers and disease severity in individual patients. On the other hand, the serum titer of the AChR antibodies does not correlate well with disease severity, and these levels are not monitored serially in clinical practice. That said, these levels are key in diagnosing MG.

AChR antibodies may not always be detectable, and it is important to keep in mind that approximately 15%-20% of patients with MG are seronegative.

Learn more about laboratory testing in MG.


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