Ahh well, therein lies the answer.  If you had your tab at 9.30 or thereabouts, and your labs taken at 4.30pm, then really that dex dose will have affected the results really.  Especially if you normally get them done @ 8am or before your morning dose of dex.  Maybe in this case, you need to re check the levels then before dropping anything dose wise.  The reason your labs were low I would have thought, is because the hormones were being suppressed by your dex dose still @ 4.30pm.  Unless you usually have your bloods drawn off their at that time consistently and then seen a change in the labs that looks like over suppression, then really you cannot rely on the results.

I’d try to get them done before the morning dose as you will have gone 24 hours without Pred dose and this will be a good gauge as to whether that previous dose covered you or was too high.  Certainly if your labs are around the 70’s then in that case you could say that you have taken too high a dose of dex for sure.  If the labs are too high, then the dose is not suitable and need’s raising some.

Regards

Anne-Marie