This gets cited here weekly, usually second-hand, so it is worth setting out what it does and does not establish.
Routine calcitonin screening is not recommended and does more harm than good in this population — the false-positive rate is high and the workup is invasive. The rodent medullary thyroid carcinoma signal that drives the labelling has not translated into a human signal, but a personal or family history of MTC or MEN2 is a genuine contraindication rather than a formality. Separately, TSH is worth having at baseline because hypothyroidism explains fatigue that people will otherwise blame on the drug.
Where I think it is weakest: the population was selected and supported in ways a real cohort is not, so I would read the effect size as a ceiling rather than an expectation.
What I am trying to establish is why calcitonin screening is not recommended when the label carries a thyroid warning, because those two facts look contradictory from the outside. Practical detail welcome, however dull — the duller the better.
Figures above are from the primary publication rather than the press summary. If a number here disagrees with one you have, post yours and we will work out which of us is reading a secondary source.
Dr.Martinez said:Routine calcitonin screening is not recommended and does more harm than good in this population — the false-positive rate is high and the workup is…
Agreed, and the adaptation point cuts both ways: tachyphylaxis to gastric emptying is why tolerability improves, and it is also why people who were relying on physical fullness feel the effect fade while the appetite effect is still working.
Dr.Martinez said:Routine calcitonin screening is not recommended and does more harm than good in this population — the false-positive rate is high and the workup is…
Thyroid cancer screening labs for thyroid monitoring — addressing the boxed warning concern with actual data:
Calcitonin level: 3.0 pg/mL (normal <10). Checked at baseline, month 6, and month 12. Rock stable, no upward trend.
Thyroid ultrasound: normal, no nodules at month 12.
The MTC risk from rodent studies has not been confirmed in human post-marketing data across millions of patient-years. The boxed warning is a regulatory precaution based on animal data. While monitoring is prudent, the clinical risk appears to be negligible.
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View ResultsThis one has a reasonably settled answer, so here it is. The mechanism is more central than most summaries suggest. Receptor agonism in the arcuate nucleus activates POMC neurons and inhibits AgRP/NPY signalling, and the downstream MC4R pathway is the same one disrupted in monogenic obesity — convergent genetic evidence that the target is the right one. Peripherally there is glucose-dependent insulin secretion, glucagon suppression and delayed gastric emptying, but the gastric component largely adapts over months while the central effect persists, which is why the durable effect is appetite rather than fullness.
If somebody has the primary source to hand I would rather cite it than paraphrase it.
BethLabQueen said:Agreed, and the adaptation point cuts both ways: tachyphylaxis to gastric emptying is why tolerability improves, and it is also why people who were…
Same experience, arrived at from the opposite direction. I had assumed I was the exception until I read this.