What causes low ferritin levels?

Dear Ask The Doctor: I am a 21 year old female who has been donating blood for 3 years and on my last donation was told that my Hb was too low (110) and that I couldn't donate. I had blood test to find out my ferretine levels and found that they were 6.69. I took these results and she has suggested that I take iron supplements and have an iron infusion. I had another ferretine about a year ago and the results were normal although i don't know what the results were. I would like to know what could have caused my iron to drop so low in this time?

Ferritin is a measure of the body’s iron stores. Most of the time, the source of iron is diet: lean red meats, seafoods are good sources. If you have been eating less of these lately, then that could cause your iron stores to get depleted. Heavy menstrual bleeding can also decrease ferritin levels. Some women are iron deficient for most of their reproductive age because they usually bleed heavy during menses. Once they get into menopause, the ferritin levels normalize. Normal ferritin levels in women is 10-200ng/mL. However, 10-80 ng/mL is considered low normal. Try asking your doctor what was the exact level of your ferritin a year ago. If you want to know of other conditions that cause low ferritin levels, these are chronic gastrointestinal bleeding, alcohol abuse, hypothyroidism, liver diseases (acute hepatitis), malnutrition and malabsorption (low absorption of nutrients) in the GI tract. Most of the time, these conditions will also have accompanying symptoms. It is also possible in your case that frequent blood donations have caused the iron stores to get depleted; remember that women lose blood every month (menstrual period), so it will be faster for the iron stores to get depleted as compared to men. You have mild anemia, not severe since your hemoglobin is slightly low. You can take the iron supplements as prescribed and perhaps the low ferritin can be corrected eventually. I do hope I have answered your question and take care always.