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12778343 tn?1427211122

Anyone have low serum cortisol AFTER 5mg prednisone?

I have secondary adrenal deficiency due to pituitary injury.  I've been taking 5mg prednisone in the morning and 5mg Cortef at noon.  Normally I have cortisol levels done in the AM without any meds; but last time, I took my labs after taking prednisone.
I took 5mg prednisone at 6 am and my 9am serum cortisol was 1.7 ug/dL.  This is much lower than my usual a.m. cortisol (5-7ug/dL).  
I did some research and an endocrinology textbook (thank you Google books!) stated "Patients taking prednisone may have falsely increased cortisol levels because prednisone is converted to prednisolone after ingestion, and prednisolone has a 41% cross-reactivity with cortisol. "  Is that true for a 5mg dose or just for huge suppressive doses (e.g., 50 mg)?  It seems very strange for me to have such a low serum cortisol reading after taking the prednisone.
Two immediate family members have a rare form of hypertension - apparent mineralocorticoid excess.  Any salt gives them dangerous hypertension, but taking cortef will lower their blood pressure.  It's due to an enzyme defect.  I wonder if I have a version of it.  Four out of five immediate family members use cortef, three of us are also hypothyroid.  So we have some strange endocrine patterns.
thank you
1 Responses
657231 tn?1453836403
Prednisone takes hours to convert as well, so if you took it at six and tested at 9, it was not fully converted to a usable form. This is why you can't use prednisone for a crisis and need hydrocortisone. Check out a steroid calculator. Prednisone is not my favorite replacement for this reason...

So your family has Conn's? Or a pheo?
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657231 tn?1453836403
Northern, NJ
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