Low iron is one of the most common things I see in women who walk through my door. It’s also one of the most common tests we run and we do this by looking at ferritin levels (a measure of iron stores in your body). The normal reference range for ferritin is anywhere from 10-291 ng/mL for women. Most often, if you’re not clinically anemic and your ferritin is within this range, you won’t be alerted to abnormal ferritin levels (even if they as low as 12, for example). However, recent studies show that women have improved energy and feel best with ferritin levels > 50, even if they’re not anemic.
Symptoms of Low Iron
Symptoms of low iron can include fatigue, low energy, hair loss, feeling cold, weak or brittle nails, palpitations or shortness of breath, brain fog and more. Many of these symptoms are also symptoms of low thyroid function or hypothyroidism. If you’ve been previously diagnosed with hypothyroidism and are still experiencing many of these symptoms, take the guess work out and have your ferritin levels checked.
Side note: If you experience heavy menstrual periods, are vegan/vegetarian, or have digestive disorders (such as celiac disease) that affect nutrient absorption, it’s also important to have your ferritin assessed on a regular basis.
The Iron-Thyroid Connection
Women are more likely to have low iron levels and we’re also more likely to have hypothyroidism or Hashimoto’s Disease (Lucky us!). We don’t usually think of iron as being essential to thyroid function, but it is!
Our thyroid needs adequate iron levels to produce the active hormones T4 and T3. If our body is low in iron, the enzyme responsible for this can be reduced in activity up to 50%. Iron is also essential to another key enzyme, which converts T4 into T3. (T3 is our most active thyroid hormone). If you are already on medication for your thyroid (such as Synthroid) having adequate iron levels is still important for converting the medication into active, usable, thyroid hormone.
There’s more: a very common symptom of hypothyroidism is low stomach acid, which decreases our ability to break down foods and absorb nutrients. Thus, a very common symptom of hypothyroidism is (you guessed it) low iron levels!
Low iron –> hypothyroidism –> low iron –> vicious cycle
So What Should My Ferritin Be?
For optimal energy and thyroid function, ferritin levels should be at or above 80 ng/mL. Hair loss or thinning can occur at levels less than 40. Anything below 30 is what I call “scraping the bottom of the iron bucket”. If your ferritin is really low, your thyroid won’t be functioning properly no matter what other medications or supplements you are taking. Most women I test ferritin levels on are somewhere between 20-50, and many are in need of some sort of iron support or supplementation. If you’ve been on iron in the past and have experienced digestive upset, constipation, or nausea, there are better supplements out there that don’t have these unwanted side effects and are more effective in bringing up iron levels.
That said, we also don’t want too much iron, as this can be harmful to the body. So supplement wisely and make sure to re-test your levels on a regular basis.
- Many symptoms of iron deficiency and hypothyroidism overlap. What you thought were low thyroid symptoms (such as fatigue and hair loss) could in fact, be due to low iron!
- Your thyroid requires adequate iron levels for TWO key enzymes that are vital to hormone production and activation.
- If you have low thyroid function or hypothyroidism, have your ferritin levels assessed and get a copy of the results. Use 80 ng/mL as a guide to optimal levels, although different people feel best at different levels.
- Ask your Naturopathic Doctor about testing your ferritin levels and if needed, the best iron supplements to increase your levels quickly without causing you digestive upset.
Want more info on the thyroid tests you need? Check out my last blog post here