Ferritin: The Blood Test Women Should Get at Every Doctor’s Visit

It was a Saturday and I had just finished running 10 miles training for a half marathon. After I got home, I couldn’t motivate to get off the couch. The day was far from over as I had plans to go to a 50^th birthday party that night.

There was no possible way for me to physically get dressed and head out for the night. I let my friend know that I wasn’t feeling well. But I wasn’t sick, just bone tired.

Four months later I discovered I was anemic. The light bulbs started to go off as I made connections between my brain fog, lack of energy, and low iron.

I felt kind of embarrassed that as a dietitian I didn’t catch this sooner. But I started to put the pieces together and realized that my doctors should have caught this earlier. That is, if they did the test that I now know every woman needs: ferritin.

And because my way of coping is to (over) research, I learned a lot.

So, let’s start with a quick review before we dig into ferritin.

Red blood cell 101

Red blood cells account for 40 percent of blood volume and are continually made in the bone marrow. They contain hemoglobin, a protein that gives blood its red color.

Iron is the heme part of hemoglobin and its job is to carry oxygen. When we breathe in, blood passes through the lungs where oxygen attaches to hemoglobin. Red blood cells then transfer oxygen to the rest of the body’s cells and tissues.

After supplying oxygen, empty red blood cells attach to waste products like carbon dioxide, which are excreted when we exhale.

The most sensitive indicator of iron status is a protein in the blood called ferritin, which reflects iron stores in the body. When iron stores decline past a certain point, the delicate balance of red blood cells gets off-kilter.

By the time the body has worked through its iron stores and full-blown anemia occurs, cells and tissues aren’t getting the oxygen they need to function properly.

Watch the big four

When iron gets out of balance, it’s because intake doesn’t meet demand. And that’s because one more of the following factors are at play.

• Decreased iron intake: When a woman doesn’t meet her needs for iron, her stores become depleted. Honestly, breastfed infants are at the greatest risk for this but so are vegetarians and vegans who may eat less iron or less absorbable sources of iron.
• High demand: There are times the body needs more iron like during growth (infants/puberty), pregnancy, and intense exercise.
• Poor absorption: Iron absorption is compromised under a variety of circumstances like in gastric bypass patients, inflammatory bowel disease, use of antacids, and celiac disease.
• Increased loss: The body loses red blood cells during menstruation, when giving blood, and with any disease that causes internal bleeding. Active people also lose iron through the gastrointestinal (GI) system, urine, and sweat.

It’s all about Ferritin

Throughout my life all doctors ever checked was a complete blood count which included hemoglobin and hematocrit to check for anemia. For me, these have always been in the normal range.

When I got diagnosed with anemia, they followed it up with a complete iron panel that checks ferritin. Less than 30 is considered iron deficiency and mine was 10.

I dug deep into my medical file where I keep old blood work from my twenties and thirties. There was no ferritin to be found! I had no idea of what my baseline ferritin was before having kids when I had relentless energy.

Women should keep track of their ferritin levels because, due to biology, they are at risk for low iron. There’s a huge range of normal depending on the lab ferritin can range from 10-307mcg/L. According to the National Institutes of Health Office of Dietary Supplements:

Serum ferritin concentration, a measure of the body’s iron stores, is currently the most efficient and cost-effective test for diagnosing iron deficiency. Because serum ferritin decreases during the first stage of iron depletion, it can identify low iron status before the onset of Iron deficiency anemia (IDA). A serum ferritin concentration lower than 30 mcg/L suggests iron deficiency, and a value lower than 10 mcg/L suggests IDA. However, serum ferritin is subject to influence by inflammation (due, for example, to infectious disease), which elevates serum ferritin concentrations.

In short, anemia is the last and more severe stage of iron deficiency. Unable to get enough oxygen, the body increases heart and breathing rate and women may experience palpitations. The body slows down resulting in fatigue, weakness, and shortness of breath. A lack of oxygen to the brain results in brain fog, headaches and/or dizziness. Feet and hands get cold, hair may fall out, and spooning of the nails can occur. See the complete symptom chart list below.

Although it is assumed these symptoms only occur at the final stage of anemia, research suggests signs may appear much earlier in the process. If women can get clues before this happens, they can avoid the decreased quality of life and health risks that go along with it.

In one study, two groups of women with ferritin levels of less than 50mcg/L were given iron supplements or a placebo. The women given the iron reported a 48% decrease in fatigue, significantly more than the placebo group.

Women have more iron loss

It all starts in adolescence with the first period. A girl’s risk for iron deficiency increases because she now loses iron. In one study, 80% of girls had ferritin levels under 40. Adding to the toll for any female is heavy periods where as many as 90% of women have low ferritin.

In another study with 236 women with heavy menstrual bleeding 63 (27%) were anemic and 140 (60%) were severely iron deficient (ferritin <15 ng/ml). Out of the anemic women, only 8% were taking iron supplements. They were treated with either hysterectomy or an IUD which stopped or decreased bleeding significantly.

A year later they all felt better in terms of energy, social functioning, and physical functioning, and iron improved. The anemic women also had decreases in anxiety and depression. But it took 5 years for ferritin to get back to normal.

Yet some women are protected from this risk if they are on birth control that keeps their flow light or stops their periods entirely.

Pregnancy increases demand

Another factor that increases the risk of low ferritin is pregnancy. Iron needs increase significantly during pregnancy to help meet the increased demands of the fetus and this accelerates the last trimester when the baby begins to store iron.

Anemia is very common during pregnancy ranging from 17% to 31% in Europe and North America, 44–53% in South East Asia, and 53–61% in Africa.

To examine the effects pregnancy has on a woman’s iron stores, researchers divided women into those who took iron supplements and those who didn’t. The ones that did not take iron (except for prenatal vitamin), had decreases in serum ferritin levels and by 28 weeks’ gestation and this was associated with erythrocyte microcytosis (smaller red blood cells) the last trimester. About 6 months after the pregnancy, ferritin levels were significantly lower than at the beginning of pregnancy.

Yet the women taking iron had no such changes and that includes a decrease in ferritin after pregnancy.

Not only does pregnancy decrease iron stores, but it also takes time to recover.

Women with back-to-back pregnancies may be at higher risk of low ferritin. And some may not recover from the decrease in ferritin especially if they start regular periods soon after pregnancy.

Other factors to consider

There are other risk factors for low iron such as being a vegan or vegetarian, frequently giving blood, and intense exercise.

Vegetarians are at increased risk because the iron in plant foods isn’t absorbed as well as animal sources. In a meta-analysis examining 13 studies, vegetarian women with low ferritin (<12mcg/l) ranged from 12% to 79%.

Another risk factor for low ferritin is regular intense exercise like running. Women involved in intense training may also have increased iron losses in sweat, urine, the GI tract. Also due to increased workload, their muscles and lungs require more oxygen.

According to an ACSM position stand:

Regardless of the etiology, a compromised iron status can negatively impact health, physical and mental performance, and warrants prompt medical intervention and monitoring. Iron requirements for all female athletes may be increased by up to 70% of the estimated average requirement. Athletes who are at greatest risk, such as distance runners, vegetarian athletes, or regular blood donors should be screened regularly and aim for an iron intake greater than their RDA (ie, >18 mg for women and >8 mg for men).

Iron supplementation in women of reproductive age has been found to aid exercise performance and lower heart rate.

Midlife is the perfect storm for iron deficiency

Using myself as an example, midlife was the perfect storm for depleted iron stores. Even though my intake of iron was adequate, having two pregnancies back-to-back followed by years of ample menstruation mixed with intense exercise meant the iron in my diet wasn’t enough to keep up with the demand and losses.

The loss of iron often accelerates at midlife. When women enter perimenopause they are likely to experience heavier and erratic cycles. According to one study of 1300 women aged 42-52, 25 percent said they had 1-3 occurrences in a 6-month period of 10 plus days of bleeding and 78 percent said they had three or more days of heavy flow during cycles. Many women had spotting and/or heavy bleeding in between irregular periods.

“This was me! My iron was so low, that my hair started to fall out,” said Irene, a midlife woman. “During a routine dentist appt (yes, the dentist) she advised to me ask for biotin, iron, and vitamin D and B12 test. I pushed for those and my dentist was right. My iron count was in the single digits.”

When women like Irene have symptoms of low iron, they may think it’s just symptoms of perimenopause and don’t seek help. Even worse, is that doctors usually only check for anemia and not ferritin levels. Or even worse than that, women get their ferritin checked and are told it’s normal even though it’s too low to function optimally.

When a normal ferritin still means low iron

As I was searching for answers I came across a very interesting paper by an internist at Eira Hospital in Helsinki Finland, Esa Soppi. He makes a convincing case for the problem of iron deficiency without anemia. He writes:

During my 30-year carrier as an internist with a special interest in thyroid diseases and hematology, I have met hundreds of patients, mainly menstruating females, who seek advice because of prolonged (1–25 years) fatigue, brain fog, muscle and joint pains, weight gain, headache, dyspnoea, palpitations, sometimes associated with sleep disturbances, arrhythmia, lump in the throat or difficulty in swallowing, and restless legs.

He goes on to explain how many of these women had different diagnoses like fibromyalgia, hypothyroidism, depression, and migraine because the symptoms are very similar, and they were told their ferritin was in the “normal” range.

Most surprising is that based on his experience, he believes that ferritin concentrations as high as 100mcg/L can still indicate low iron status. Dr. Soppi says as long as women have symptoms of iron deficiency, it’s worthwhile to supplement with iron. He puts it this way:

If symptoms are in accordance with iron deficiency, the patient should be considered iron deficient at least up to a serum ferritin concentration of 100 mcg/L, or even much higher, if the patient has an inflammatory condition, kidney disease or fatty liver. Iron deficiency irrespective of manifestation should always be treated. Patients with true iron deficiency anemia on the basis of negative bone marrow iron staining may have a serum ferritin concentration close to 50 mcg/L. Patients with restless leg syndrome should be considered iron-deficient when their ferritin concentration is <75 mcg/L.

Adding to the problem is iron deficiency can negatively impact the thyroid since it’s required for thyroid hormone production and the conversion of T4 to T3. That also means that thyroid problems can cause low iron making knowing your ferritin if you have thyroid problems especially important.

“I have found that low ferritin levels have been the missing link in some patients with hypothyroidism who just can’t seem to get their thyroid levels in balance,” writes Dr. Hedberg, D.C. a functional medicine doctor who specializes in thyroid issues. “If you have a thyroid problem, definitely have your ferritin levels checked to make sure your ferritin is not too high or too low.”

It’s important to note that ferritin levels can increase when there’s an infection or inflammation, which happens about 10% of the time. Additionally, some people absorb too much iron because they have hemochromatosis or other health condition. This is why it’s important to have an entire iron panel done and consult with a doctor. Especially looking at transferrin saturation. Anything less than 20% is linked to iron deficiency and when it’s great than 45%, iron overload.

How much to take?

Faced with a ferritin of 10 and anemia, I couldn’t believe my doctor recommended a multivitamin with iron (now ex-doctor). Research shows iron in a multi is not as effective in bringing up iron as iron alone.

As for goals for my ferritin level, without a baseline level, I went with the advice from Dr. Soppi and watched my symptoms.

Although it’s still common for doctors to prescribe high levels of 100-200mg of elemental iron throughout the day, high doses often result in GI disturbances like constipation and nausea. And research shows less iron (60-80mg elemental) taken every other day may be tolerated better.

That’s because when the body gets flooded with iron it releases more of the hormone hepcidin, which suppresses iron absorption. In one study women were getting iron every day or every other day for 14 days. The total absorption in the everyday iron group was 131mg versus 175mg in the alternate-day group. Serum hepcidin was higher in the everyday group.

I took 65mg every day and eventually switched to every other day. My levels went up fast and I have found that ferritin of at least 50mcg/L keeps my symptoms away. Other research points to that 50 cut-off too. To maintain that, I take iron once a week and a couple of times during my cycles.

In one study, weekly iron for 16 weeks of 60mg elemental iron (check labels) was enough to raise ferritin from 27.97 to 45.45 in adolescent girls.

When possible, take iron one to two hours before or after a meal and avoid taking it with milk, caffeine, calcium, or antacids. Taking it with 250mg vitamin C will help it absorb better. See this article for information on iron infusions. 

Remember that iron supplements usually come as ferrous sulfate. You want to check the amount of elemental iron. For example, 325mg ferrous sulfate contains 65mg elemental iron. Keep iron pills away from children.

What about diet?

The RDA for iron for women under 50 is 18mg and that drops to 8mg after 50. When it comes to iron deficiency with or without anemia, this amount is not enough to raise levels. I eat well-rounded meals with iron sources of both plant and animal origin and plenty of vitamin C.

A 2015 study in The Journal of Nutrition found that absorption rates of iron may not be as high as we think. Researchers found a 15% absorption rate, lower than the 18% typically cited. Absorption from plant foods is about 5-7% and animal foods 25%. The researchers write:

Despite global efforts to improve iron nutrition in at-risk populations, iron deficiency anemia remains a challenge. In the United States, the prevalence of iron deficiency is high even at the present in certain populations, even when the diet is high in heme iron and most foods are fortified with iron. One possible explanation for this persistent deficiency is that the bioavailability of iron in the diet of Americans has been overestimated.

If you want to increase iron, adding animal foods makes sense but women at midlife may find this isn’t an ideal health goal. Additionally, healthy plant-based foods contain iron inhibitors such as polyphenols, oxalates, and phytates. Foods and supplements rich in calcium and eggs are inhibitors as well.

Yet supplementing can easily help fill the gaps and it’s easier to take iron without food and additional vitamin C. I’ve learned the hard way that a little extra iron goes a long way.

Know your ferritin

This whole experience just made me upset as so many girls and women suffer needlessly. Shouldn’t we all be educated about the importance of ferritin at some point in our lives?

It’s true that as women stop menstruating their risk of iron deficiency decreases. Yet according to the aforementioned study, it can take ferritin five years to return to normal without taking iron. Also, one of the big four could still cause low ferritin although it’s less likely.

I hope there’s a day where we will know our ferritin just like we know our cholesterol. Then, just maybe, we can get control of the world’s leading nutrition deficiency.

Do you know your ferritin?

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