It's not a routine question. There's a specific reason it comes up before every GLP-1 prescription.
The MTC concern
Medullary thyroid carcinoma (MTC) is a rare cancer of the thyroid C-cells. In rodent studies, GLP-1 medications increased C-cell tumours. The signal hasn't been confirmed in humans, but caution is built into prescribing.
Hard contraindications
Personal history of MTC, or Multiple Endocrine Neoplasia syndrome type 2 (MEN-2) — a rare inherited condition that predisposes to MTC. Either rules out GLP-1 therapy.
Family history
We ask about it. A first-degree relative with MTC pushes us to a specialist endocrinologist consult before prescribing.
Why this isn't a 'cancer drug'
The overall population data don't show elevated thyroid cancer in GLP-1 users. The screening exists because we manage the small unconfirmed risk by excluding the people in whom it would matter.
