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hi,
Q::if the calcitonin`s function(originated from the C cells) is to decrease the calcium..
then how does the thyroid medullary hyperplasia which will turn into medullary thyroid carcinoma....>has increased Calcitonin(from c cells) AND increased Calcium???
i found this at the UW and can`t get it,plz explain asap
THANKS in advance
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I GUESS the increased calcitonin might not be functional.
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Calcitonin is released normally or (abnormally some times = your example) in response to increase in ca++ caused by PTH induced resorption of bone by OCA factor. It's function is to decrease plasma ca++ by decreasing the osteoclast activity, but it never succeds as PTH activity to activate osteoclasts (indirect through osteoblast) dominates over it. So net net lab result will be High calcitonin and High ca++
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i think this is because medullary thyroid ca .. usually (50%) being part of MEN 2 a or b
in a u have hyperparathyroid ... with high Ca
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You are right about this.
Another possible explaination: In case of any cancerous lesion there will be an increase in IL-1 (same as OCA factor that PTH induces). This IL-1 causes resorption of bone through osteoclasts activation causing high ca++ & Low PTH (High in MEN2). Calcitonin is a marker for medullary type cancer & will be elevated.
So right answer will depend on what the Q stem says.
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