It's said that a reservoir of topical hormone products forms around the application site, so that would probably skew any blood tests taken near to that area, and as pepperminty says, it can spread. I would have thought with T though, compared to Oestrogel, it's such a small amount, it couldn't realistically spread from wrist to as far as the elbow, so probably wouldn't distort any blood tests imho.
I apply Androfeme to my upper thigh, as advised by the manufacturer, at the recommended dose. My last blood test showed slightly high total T levels but also higher than expected oestradiol levels (given all the issues with Oestrogel). So I'm happy that I'm absorbing T well ( and not getting any side effects or hairiness) but unsure as to the cause of high oestradiol - conversion from T or skewed from applying to my arm? I will be doing a further test not applying E to my arms and see. Nothing is straightforward is it?