We used Hydrocort 2% cream for my son’s eczema at one point.  I wondered about bloodwork too, and called our endo.  We were advised to discontinue use of the cream for one full week before labs, just to be sure that it didn’t skew his results.  At the time though, he was a 13 lb. infant, and I’m sure that had something to do with it.  My advice would be to call the endo for advice if at all possible.  If not, I would err on the side of caution and discontinue use for a week before labs.

On the eczema issue, we’ve found that bathing every other day using as little of a mild cleanser as possible, then slathering damp skin with Aveeno Baby Cream ( different from the daily lotion) has been very helpful.  We also moisturize throughout the day with Aveeno Baby Daily Lotion.  Another product that is a godsend is Gerber Little Faces Moisturizing Stick.  It looks like a very large chapstick and has wonderful ingredients like shea butter, aloe, etc.  We keep one of these in each baby bag and apply whenever his skin looks dry.  The nice thing about this one is that it is very rich and moisturizing, but does not leave his face looking shiny.

Good luck with this, I know it’s hard to see your little one suffering with it.

Blessings,