My son has vit d deficiency 24(normal value is above 30)one dr told me to give him 1200 iu/day& another said 4000iu/d. he is only 8. what is correct?

Try 4000 first,then:: You want to get his level up to 50-80 which is optimal. Most adults need 5000-8000 iu/day to get to these levels so I would give about half that dose, up to 4000 for about a month to bring his levels up quickly, then it will probably take 2-3000 a day to maintain a good level. But recheck his level in 2-3 months and adjust accordingly. It takes massive doses to overdose and 4000 is safe for now.