I wouldn't get too far ahead of yourself, worrying about having to have him re-tested. Keep in mind that IQ scores are quite unstable at this age, so even if he doesn't test at a number consistent with your everyday experience of him, it doesn't necessarily mean it was a bad test. Little children are just a bit unpredictable in their response to and presentation on testing. It's more important to focus on the information, guidance, and supports you get out of testing, than on the precise numbers.
ITA
no, the cognitive test will not pick up on dyslexia or such issues. These need to be teased out separately.
Also agreed. The IQ test may be *impacted* by dyslexia or other LDs, but you'll not have the full information you'll need to know that your child is dyslexic. To diagnose an LD a wide variety of information is usually taken into account: ability/achievement testing is part of it, classroom and parental observations, classwork/homework samples, and further testing to pinpoint the exact nature of the observed challenges. Most kids with LDs aren't diagnosed until they've been in school for a little while. You're ahead of the game since your ds has a preschool teacher who's identified a potential concern.
When you asked the school for testing, were you asking specifically for dyslexia testing or for gifted testing? If you are concerned about testing, there are other things you should be able to ask to have included that are specifically targeted at reading - although I don't know if they are available for the age your ds is. One thing you might request through school or pursue on your own is vision/hearing testing.
Best wishes,
polarbear
