epc924
Forum Junior
Topics: 11
Posts: 60
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A 3 yr old boy has a mutation in the calcium receptors on cell surfaces of his parathyroid gland and on the basolateral (blood) side of the thick ascending limb of loop of Henle. Which of the following patterns is expected with a mutation that leads to activation of this receptor in teh absence of binding of its ligand calcium?
the answer is : Hypocalcemia and PTH level is low, and Urine calcium level is high.
can anyone explain why that is? cuz i thought if there is a mutation of those receptors wouldnt that cause excess of calcium reabsorption with presence of PTH and lead to
hypercalcemia , low PTH level and low Urine calcium??
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| taipei817
Forum Newbie
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Posts: 68
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constitutive activation of the mutated receptor in the absence of Ca means that the parathyroid gland thinks the blood has too many Ca. thus, it will decrease PTH secretion
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| epc924
Forum Junior
Topics: 11
Posts: 60
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okay .. thanks for the info taipei817...
do u mind share when u read this info?? cuz i looked BRS physio but i couldnt find related
answer 
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| taipei817
Forum Newbie
Topics: 1
Posts: 68
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um sorry  ... i dont think i have anything to back me up specifically. I just thought along the line that Ca feeds back to PTH gland to regulate PTH hormone secretion.
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| WolfgangWhite
Forum Newbie
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Id like to see the exact wording of the original question with all the other answers . if you wouldn't mind?
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| lakshya_0_7
Forum Elite
Topics: 19
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hey epc.......i did NBME-2 yesterday........i thought the answer to be:
increase calcium (becoz the receptor on the Loop help reabsorb the calcium coz its activated no matter what the PTH level is)
decrease PTH (the receptor for calcium is activated so the Parathyroid gland gets negative feedback and doesnt secrete PHT)
decrease calcium in the urine........(coz it got reabsorbed )
where do people get answers of NBME forms???how did u come to know the correct ans??
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