Ordering VGCC Testing and Navigating NCCN Guidelines for LEMS

This episode, "Ordering VGCC Testing and Navigating NCCN Guidelines for LEMS," features the panel examining the practical mechanics of VGCC testing.

Dr. Iams asks how Dr. Patel orders voltage-gated calcium channel (VGCC) testing and what the process looks like at his center. Dr. Patel explains that his institution has a large reference laboratory offering a VGCC antibody panel, though he cautions that smaller and community centers may not have this test readily available and will need to identify a reference lab that offers similar testing. Ordering often requires a special order or even a faxed paper form, and clinicians must account for requirements such as specific collection tubes, narrow stability windows, and set run days, since these details matter for a test not commonly ordered in daily practice. Dr. Iams shares that his own training experience involved a broad neurologic paraneoplastic panel that took a month or more to return, often outlasting the patient's hospital stay. In the community setting today, he says, VGCC-specific assays through labs may return results in roughly 1 to 2 weeks, a meaningful improvement in access. He then turns to NCCN guidelines, which now explicitly recommend a high index of suspicion for LEMS in SCLC and support PQ- and N-type VGCC testing in consultation with neurology. Dr. Patel adds that this reminder is valuable precisely because oncologists are often narrowly focused on starting cancer treatment quickly. Dr. Iams argues that the threshold for testing needs to be lower than the historical bar of hospitalization for profound weakness, and asks how Dr. Patel approaches neurology referral timing, since inpatient consults are far more accessible than outpatient ones. Dr. Patel says he would welcome neurology involvement but also wants to build comfort managing LEMS himself, given that specialist access can take weeks or months, while noting that a specialist remains invaluable whenever available.

Our next episode, "LEMS Treatment Mechanisms: Immunosuppression, Plasma Exchange, and Potassium Channel Blockade," turns to how Dr. Patel and Dr. Iams actually treat LEMS once a diagnosis is confirmed.