I had this with DS, the HV at his 1 year checkup thought he looked pale.
Basically it's nothing to worry about - the anaemia is very common in toddlers because they tend to eat low-iron, dairy-rich diets (doc told me over half have it, most undiagnosed) and can make them a bit tired and more prone to colds and stuff and can be sorted out with iron supplements v easily.
Some docs prefer just to supplement without bothering with the bloods, but my doc said the supplements can cause constipation so he prefers to check whether they are necessary.
The reason they test for kidney function and stuff is because anaemia can sometimes be caused by kidney and other problems, so if they do find a child has anaemia, they then have to go back and test for kidneys etc. It just saves more blood tests for your poor DD if they do find low iron. Most anaemia is purely diet related though, and nothing to worry about.
Anyway my DS is pale as a ghost, just like me at his age, and his iron turned out to be fine - on the low side but within normal boundaries and not requiring supplements.
So hopefully it will all be a false alarm
HTH