How to test for iron deficiency accurately

Last week we discussed iron deficiency, which you can catch up on here if you missed it! Iron Deficiency can cause significant symptoms, so it’s important that we identify it as soon as we can. If you have a menstrual cycle, had a baby recently, have had a deficiency in the past, or donate blood regularly - you should get tested.

Iron testing is also a little bit complicated. The most thorough testing (which I highly recommend) includes a Complete Blood Cell count (CBC - which looks at the size and shape of your blood cells), Iron panel (iron in blood, transporters and saturation), and Ferritin (a marker of iron storage).

Too often I just see the CBC (complete blood cell count) is done, the hemoglobin looks ‘normal’, and you’re told your iron was fine, even though the iron itself was never actually tested. If your hemoglobin is normal it means you don’t have anemia, but you could STILL have iron deficiency. 

Hemoglobin is often the LAST marker to change as your iron gets low. We want to know more about your iron’s actual status, as just iron deficiency itself (even without anemia) causes significant symptoms.  

Ferritin is a good maker of iron storage, anything <30 (and arguably <35) would be considered iron deficiency. Most people feel best when their ferritin is at least 50+.

For someone with an inflammatory condition (PCOS, Hashimotos, arthritis etc.), or if you had blood work while fighting a cold, ferritin may actually NOT be the best marker as inflammation/infection will cause it to rise and look normal where it may actually be abnormal.  In this case an iron panel, specifically transferrin saturation is most important and should be at least 0.2.  

I’ve seen many people with a ferritin level of 15 that were never told it’s a problem, so always get a copy of your own bloodwork and look for yourself! It’s important to consider that if you’re experiencing heavier menstrual bleeding (losing >80mL in a cycle) and even if ferritin at this time is a little bit higher than 35, you may still be at risk of iron deficiency. You can read up on this here.

So, all this being said, why do we need to know the exact numbers? So we can treat, and then retest to make sure that it’s working! These are tests that I can order, so please don’t hesitate to reach out if it’s been a while since these levels were assessed or if your suspect they weren’t assessed thoroughly.