Step I NBME bone q

[MudPhud20XX]

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A 65 yr old woman comes to the physician for a follow-up examination after a DEXA scan showed a decrease in bone density. Physical examination shows no abnormalities. Which one of the following sets of findings in bone is most likely in this patient?

So she is most likely in menopause so should have low osteoblast and high osteoclast right? So I am debating between D and E, right? Can anyone explain how to approach for the third column? Many thanks in advance.

 

[Halothane27]

Yup that's right. Osteoblasts= low, osteoclasts= high (no apoptosis due to lack to estrogen) and RANKL= high. The reason is that osteoclasts need something to tell it to start working on reabosrbing bone. And that signal is RANKL.

RANK-L on Osteoblast increase- which then in turn bind RANK on osteoclasts.


As a side note : There seems to be an error in FA2014 page 314
the correct sequence is that PTH increases expression of RANK-L on osteoblasts, which then binds RANK on Osteoclasts. The receptor for RANK are on the osteroclasts. Osteoclasts then eat bone

 

[SBR249]

RANKL is the signal peptide ligand secreted by the osteoblasts that promote osteoclast differentiation. It's levels will correlate positively with osteoclast activity.