Low blood iron levels are usually due to loss of blood rather than dietary deficiencies.
In women past or present menstrual bleeding is the commonest cause. Low potassium,if not due to diuretic medications or steroids,may occur with vomiting or diarrhea,and less likely rare glandular problems. Low vit D is due to low calcium intake and lack of Sun exposure.YOur physician knows you best,however.
Would you like to video or text chat with me?