Reply To: I recently donated blood at a blood drive, then four days later, I received my Vitamin D home test kit in the mail. I collected my sample that evening, and mailed the card in. I have not received the result back yet. Now I am wondering if I should have waited longer after donating blood before testing my blood for Vitamin D. I donated one unit of whole blood (one pint). Will my Vitamin D test result be affected by the donation?