Is iron supplementation ever warranted if ferritin is somewhat low? 30 ng/ml(ref 6-137). no anemia, normal cbc. i know gp needs to guide meds, but curious if low ferritin can cause symptoms. can b12 injections for def. use up iron stores?

If your Hemoglobin is normal(12-13 Gms. for females), there is no reason to test any further. Your Ferritin is in the normal range, so you do not need iron supplements.

If you have heavy periods, iron supplementation would be useful in preventing depletion of iron stores. Take a multivitamin as well to facilitate iron absorption and blood formation. B12 does not use up iron stores. For diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs.