What's the deal with carotene?

[Marquis Mark]

They tested twice me for carotene and it came in at 2 both times (normal range 4-51), but my Vitamin A is fine. I tried to explain to them that this was probably OK for me given I have the DS but I really wasn't armed with the facts to explain it.

Can somebody give me a basic explanation about why we shouldn't worry too much about carotene. Or should we be? Maybe I heard wrong.