Low Plasma Metanephrine Values–Steroids, Hypotension


Question

I am a practicing clinical endocrinologist. i was asked to see a patient with cns lymphoma who had been treated with high dose steroids and chemotherapy. when the steroids were tapered he developed severe postural hypotension that responded partially to mitodrine and florinef. when steroids were restarted due to cns symptoms without evidence of definite anatomic recurrence of lyphoma the postural hypotension improved significantly. an acth stimulation teat while on steroids showed a normal serum cortisol response. however, plasma metanephrines were below detection limit. can you explain the low metanephrines? George Gewirtz, MD,

Response

Very interesting. Metanephrines reflect epinephrine secretion from the medulla, and need adrenal cortisol to be methylated from norepinephrine. I suspect there may be pituitary involvement by the lymphoma (we reported a couple of cases in "Pituitary" a few years back) and he is now ACTH deficient (this will not show up acutely in the ACTH stimulation test). If so, he should have replacement therapy with hydrocortisone. In time, I would anticipate the metanephrines will normalise. However, I frequently see patients who are normal with very low urinary catecholamines (we are not currently using metanephrines). Ashley Grossman, M D