Step II Epinephrine catabolites means adrenal pheochromocytoma?

[ChessMaster3000]

Advertisement - Members don't see this ad

I came across a strange question in UW that basically said a pt had elevated catabolites of both norepi and epinephrine, and because of the epinephrine catabolites, the pheochromocytoma MUST be in the adrenal. Whereas if it was just norepinephrine, it could have been extra-adrenal. Has anyone learned this or read this anywhere else? I was baffled

 

[Phloston]

As far as I'm aware, cortisol upregulates phenylethanolamine-N-methyltransferase, which converts NE to E. And the adrenal cortical venous drainage, which carries cortisol, passes through the medulla, which is why the body's E:NE ratio is usually 80:20.

My guess would be that an adrenal medullary tumor has an upregulation at a cellular level independent of the NE to E conversion, since that's merely enzymatic, so we'd expect an 80:20 E:NE (and their respective breakdown products) manifestation with an adrenal pheo.

An extra-adrenal pheo (e.g., organ of Zuckerkandl), in contrast, wouldn't have a means to convert NE to E as readily, since it's not exposed to high local concentrations of cortisol, so the NE:E ratio is drastically shifted to favor NE.

 

[ChessMaster3000]

As far as I'm aware, cortisol upregulates phenylethanolamine-N-methyltransferase, which converts NE to E. And the adrenal cortical venous drainage, which carries cortisol, passes through the medulla, which is why the body's E:NE ratio is usually 80:20.

My guess would be that an adrenal medullary tumor has an upregulation at a cellular level independent of the NE to E conversion, since that's merely enzymatic, so we'd expect an 80:20 E:NE (and their respective breakdown products) manifestation with an adrenal pheo.

An extra-adrenal pheo (e.g., organ of Zuckerkandl), in contrast, wouldn't have a means to convert NE to E as readily, since it's not exposed to high local concentrations of cortisol, so the NE:E ratio is drastically shifted to favor NE.

nice. good way to think about it.