Hormones and arrows

[teratomas]

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So if a patient is given exogenous hormones such as testosterone or cortisol..and a question asks how the levels of the axis change.. I get that for example crh and ACTH will go down but what happens to the levels of the actual hormone...

Is it decreased due to inhibition of the axis (saw a uworld question with this answer) or does the hormone go up because you are giving it to the pt (first aid has increased testosterone levels written for when you give exogenous testosterone on pg 524)

Any help would be appreciated.

 

[FIREitUP]

So if a patient is given exogenous hormones such as testosterone or cortisol..and a question asks how the levels of the axis change.. I get that for example crh and ACTH will go down but what happens to the levels of the actual hormone...

Is it decreased due to inhibition of the axis (saw a uworld question with this answer) or does the hormone go up because you are giving it to the pt (first aid has increased testosterone levels written for when you give exogenous testosterone on pg 524)

Any help would be appreciated.

it would probably be increased; why would you be giving exogenous hormone if you wanted to give less of it? furthermore, if you gave less than normal it would probably only partially inhibit the axis leading to the body making just enough to keep it at normal physiological levels.

 

[Myxedema]

It would be increased. Another example for that would be the Cushing's syndrome (=excess cortisol). The most common cause of Cushing's syndrome is exogenous corticosteroid usage, where excess cortisol suppresses ACTH secretion from the pituitary.

So, in a Cushing's syndrome caused by exogenous corticosteroid use, plasma cortisol levels can be elevated (but keep in mind that plasma cortisol levels are pulsatile), 24 h urinary free cortisol would be elevated (which is a better marker for plasma cortisol levels), and ACTH would be decreased.

 

[Wordead]

As with most things, the real answer is "it depends".

As in the above cases, the actual hormone is increased since the exogenous hormone is identical or causes increased production of the same hormone.

In cases where the exogenous hormone given is NOT identical to what you test for (ie PTHrP), the hormone you test for (PTH) is DECREASED. There are probably other examples of this, but I don't recall for sure (maybe some testosterone analogs?).

 

[teratomas]

What if you give a patient glucocorticoids or prednisone? Still increased or are those not the same as the endogenous form?

 

[Wordead]

What if you give a patient glucocorticoids or prednisone? Still increased or are those not the same as the endogenous form?

Hopefully someone still in step 1 study mode can give you a better answer...I know hydrocortisone is identical to cortisol, but no idea on the other ones.