What causes serum vitamin d of 24 in a 23wf if she is taking multivitamins . is there a concern ?

Needs more Vitamin D: She should check how much Vitamin D is in the multivit and aim for about 2000 units a day. Get level rechecked in 1-2 months and increase dose if necessary, The 24 is a low level,you're aiming for 40-60. Can also eat foods with Vit D like dairy. Good luck

Vitamin D: Agree with Dr Fischer, as likely amount of Vitamin D is far too low in a multivitamin, but additionally, there is likely decreased delivery on ingestion. Take the D-3 separately, get exposure to sunshine without sunblock to allow skin absorption. It is fat soluble, so increased serum levels will take 2-3 months. 2000 i.u. should be adequate.