Try to imagine that what your trying to ascertain is whether each dose is stretching to the next one adequately enough.  Then think of the best way you can go about finding out this information.  For example, if blood is drawn 2 hours after the childs dose of pediapred, does it really tell you if that dose lasts for the duration that it should.  I.e. 12 hours?  It would not do that when you think about it that way, because the dose would be very high in the blood serum, and you would be non the wiser as to whether it really did what it was supposed to do for the duration or whether it was so large that 17 OHP levels were still low in the evening or too high.    

If you want to know that the evening dose of pediapred is doing it’s work adequately for 12 hours (or even hydrocortisone for 6-8 hours) you need to give the dose, and then check the blood just before your due to give the next one, because thats how long your childs x2 a day dose has to last.  If you have the blood done at 8am before the pediapred is given it will give you exactly what is happening at that point and whether the last dose was too bog, too small or just right.  

We always have our bloods drawn before the am dose is given, because once it has been given, it taints the results in a way that you have no way of knowing if the last dose did it job really.  Important to know if it is covering the child for the period that they need it and that 17 OHP levels are neither stomped all over (which would mean over treatment) or that they are way out of whack meaning under treatment.  The ranges would be best read between 500-1000 ng/dl at that point no matter which drug was used I’d say.