Like Valerie's, our ped. endo generally prefers testing urine to blood, though we will also go for blood tests if we are trying to pinpoint something specific.  He is also trained in the US and is a GREAT doctor, with impeccable credentials (will be happy to list them all for anyone interested....I DO love the opportunity to brag about him, after all!!!), so I have the utmost confidence that he knows what he is doing.  ( As an aside, we did also see a different doctor for about 3 months---none other than Dr. New, no less---who took only blood, so Ifeel I can speak from first hand experience about both testing methods.)

The basic advantage of the urine samples is that they give a picture of control across an entire 24-hour period, unlike blood, which gives numbers for a specific point in time.  In that way, urine testing is not unlike finger-prick testing, in terms of being able to assess levels at different times of the day.  Because the picture of control is much more complete, our doctor---like Valerie's---feels that this method is actually more accurate than doing a one-time blood draw.  

We have only to read back through a couple of the recent threads (e.g. Sandra's 9/13 Endo Lab work...morning or afternoon better?  or Maheran's 9/17 Shouldn't Bloodwork give a Warning?), as well as some of the concerns posted on this thread, to realize that there are so many factors that can affect blood results (stress, circadian rhythm, before meds or after, etc., etc.), that a single number incorrectly interpreted, or taken out of context, can sometimes give a misleading---if not completely inaccurate---picture of control.  By taking samples from all different times of the day---and under all conditions---that problem, in effect, is eliminated with the urine testing. 

Yes, the samples are difficult to collect for those children who are infants or not toilet-trained (quite honestly, I don't know how our doctor tests babies---I would guess he takes blood because there is no other good choice), but for the child who is toilet-trained, they are not difficult, at all.  In fact, compared to some of the stories from parents who have children who are hard sticks (like Chris D.'s son), the process is probably a piece of cake, once you've got a system down. 

My son is actually very good with needles and blood tests (he once laughed after getting a Lupron injection and asked if that was all there was to it---the first time she'd seen that reaction, according to the nurse who gave him the shot), but I still prefer doing the urine samples.  My son's biggest problem is impatience, and it is much easier for us to have him pee into a jug, while he's going about the business of the day, rather than having to regularly lug him around to another hospital waiting room.  Got to pick your evils, I guess.