Restless Legs: A Red Flag for Iron Deficiency?

You can’t seem to get comfortable. Whether it’s on the couch, watching TV, riding in a car, or reclining in bed, your legs want to move.

In fact, your legs may even move without your bidding. The muscles twitch, demanding a massage, a quick walk, a warm bath, or stretches—anything to get them to relax. If you’ve had this experience, you might be describing restless legs syndrome (RLS).

What is restless legs syndrome?

Restless legs syndrome (RLS) can occur at any time of day, but it’s been classified as a sleep disorder because of its tendency to activate at bedtime, making it nearly impossible for some people to fall asleep. It’s fairly common; it’s estimated to affect up to 10 percent of the US population.¹

When people go to the doctor with this complaint, they may be disappointed to learn there isn’t a single test that can identify it. However, a doctor can diagnose it based on an evaluation, which may include a blood draw to measure the levels of iron in your blood.

It turns out that iron deficiency may be present in up to a quarter of all people with RLS.²

Iron deficiency and RLS: What Dr. Ekbom found

Seventy years ago, one of the two doctors who first described RLS (otherwise known as Willis-Ekbom disease) discovered the link between low iron and uncomfortable movements in the legs.

Why iron?

Especially as it relates to our bodies at bedtime, blood iron plays an important role in our circadian system. Its levels may naturally “dip” at bedtime due to these intrinsic rhythms of the body clock.

However, iron also controls levels of dopamine, a substance in the brain which regulates the fluidity of our physical body movements. If dopamine also takes a “dip” with iron at bedtime, RLS may result. Other research also suggests that when the brain doesn’t store and transport blood iron properly, RLS can also result.²

Women may have added reason to be concerned. Research shows that about a third of premenopausal women experience aggravated RLS during their menstrual cycles.³

What about that blood test?

When your blood is drawn to check for iron, the doctor is not looking only for iron levels, but for something called ferritin. Iron molecules bind to ferritin, a protein in the blood which helps to maintain the brain’s storage and distribution of iron.

Scientists have found that, while iron levels may fluctuate up and down all day (due, in part, to circadian variations), ferritin levels are far more accurate, stable, and reliable for identifying RLS.

Low ferritin in your blood draw can confirm iron deficiency as the cause of your RLS.² In this case, you’ll probably go on an oral iron supplement to help you maintain healthy ferritin levels. But beware: You’re best advised to do this under the careful observation of a physician. Self-treatment over presumed (but unconfirmed) iron deficiency can be dangerous; you can overdo iron supplementation especially if you don’t have iron-poor blood.

The only way to really know you have adequate iron levels or that you’re getting the right amount of supplementation? Through follow-up blood tests.

Is iron deficiency the same as anemia?

Not exactly. Anemia describes a shortage of red blood cells (RBCs) in your bloodstream. This is an important shortage to correct, as it’s these RBCs which deliver the protein known as hemoglobin.

When we inhale, the oxygen molecules we breathe in attach to hemoglobin for delivery to all cells in the body. Without adequate hemoglobin—due to low RBCs—we can’t adequately oxygenate our cells.⁴

Iron deficiency anemia, however, describes a common kind of anemia in which blood iron is inadequate. Most commonly it’s caused by blood loss from an injury, internal hemorrhaging, or heavy menstrual cycles. It can also be the result of the blood’s inability to adequately absorb iron molecules.⁴

When iron levels aren’t the problem

If you undergo blood iron/ferritin tests to check for a direct cause linked to your restless leg complaints, you may learn that your levels check out just fine. In that case, there may be other root causes of your RLS, such as:¹

• Dopamine imbalances
• Genetics
• Other health conditions (i.e., kidney disease or nerve pain)
• Medication side effects (including, but not limited to, antidepressants, antihistamines, and antinausea drugs)
• Pregnancy
• Heavy usage of alcohol, caffeine, or nicotine
• Sleep deprivation

Consulting with a doctor is your best avenue for treating RLS.

Simple relief for restless legs

If you’re still waiting to see a doctor and need relief at bedtime, consider:⁵

• Light stretching or massage
• Hot or cold compresses applied to the legs
• Topical magnesium sprays
• Weighted blankets
• Avoiding known triggers before bedtime (i.e. sugar, dairy, tobacco, caffeine and alcohol)

These can give you a temporary and much-desired break from RLS.