Your child's bloodwork came back "normal." That's reassuring. But a standard blood count doesn't always tell the whole iron story.

A 2026 study found that low iron stores were more than twice as common in children with ADHD as in children without it. Every child in the study had a normal blood count. If your child struggles with focus, energy or mood, here's what this research means for your family, and what it doesn't.

What is ferritin?

Infographic comparing two piggy banks: a full spending account labelled hemoglobin and an empty savings account labelled ferritin (iron stores), showing that iron stores can run low before a blood count looks off

Think of iron like money. Ferritin is your child's iron savings account. Hemoglobin, the number on a standard complete blood count (CBC), is more like the spending account.

The body protects the spending account first. So iron savings can run low for months before hemoglobin drops. By the time a CBC looks off, stores have often been low for a while.

Iron matters for more than energy. The brain uses it to make dopamine, a chemical messenger involved in attention and motivation. It's also needed for healthy sleep, growth and learning.

What the new study found

Researchers compared 100 children aged 6 to 12: 50 with ADHD and 50 without, matched by age and sex. The results were published in BMC Pediatrics in 2026.

  • Low iron stores (ferritin under 30 ng/mL) were found in 34% of children with ADHD, compared with 14% of children without ADHD.

  • Average ferritin was 38 ng/mL in the ADHD group and 51 ng/mL in the comparison group.

  • Serum iron was also lower in children with ADHD.

  • Hemoglobin and red blood cell measures were normal in both groups.

That last point is the big one. A routine CBC would have missed every one of these low iron stores.

Only ferritin showed the gap.

Why a routine blood test can miss low iron

Iron deficiency happens in stages.

First, stores (ferritin) drop. Later, if nothing changes, hemoglobin falls and anemia develops. A CBC only catches the later stage.

Two more things can make results look reassuring when they aren't:

  • Lab ranges vary. The lowest "normal" ferritin on some lab reports is quite low. This study used a cut-off of 30 ng/mL, which is higher than some lab ranges.

  • Illness can raise ferritin. Ferritin rises with infection or inflammation. A test taken during or just after a cold can look better than your child's true iron stores.

This is why interpreting ferritin takes context, not just a glance at whether it's flagged.

What this study doesn't tell us

It's just as important to be clear about the limits.

  • It was small. 100 children from a single hospital.

  • It can't show cause. It doesn't prove low iron causes ADHD, or that ADHD leads to low iron.

  • No treatment was tested. We don't know from this study whether raising iron changes attention.

  • Research is mixed. Some earlier studies found lower ferritin in children with ADHD. Others found no difference.

So low iron isn't "the answer" to ADHD. But it's a piece of the picture that's easy to check and easy to miss.

Signs your child's iron may be running low

  • Tiredness or low stamina

  • Irritability or big emotions

  • Trouble focusing

  • Restless sleep or restless legs at night

  • Pale skin or frequent infections

Many of these overlap with attention concerns. That overlap is exactly why it's worth checking.

Common reasons kids run low on iron

  • Picky eating, especially with few meats, beans or fortified foods. (Is your child a picky eater?)

  • A lot of cow's milk. Milk is low in iron and can fill little tummies. A common guideline for toddlers is no more than about 2 cups (500 mL) a day. (Is your child drinking too much milk?)

  • Growth spurts, when needs jump quickly

  • Plant-based eating that isn't carefully planned

  • Periods in teen girls

Iron-rich foods for kids (and how to absorb more)

Iron from animal foods is absorbed most easily. Iron from plant foods needs a little help.

Iron-rich foods to include:

  • Beef, chicken and turkey

  • Eggs

  • Lentils, chickpeas and beans

  • Pumpkin seeds and seed butters

  • Iron-fortified cereals and oatmeal

  • Spinach and other leafy greens

Absorption tips:

  • Pair plant iron with vitamin C, such as berries, oranges, kiwi, peppers or tomatoes.

  • Serve milk between meals rather than with iron-rich meals.

  • For teens, keep tea away from meals, since it can reduce absorption.

Why you shouldn't start iron supplements without testing

It can be tempting to grab an iron supplement "just in case." Please don't.

  • Too much iron is harmful. The body has no easy way to get rid of extra iron.

  • Iron is a serious poisoning risk for young children. Keep any iron-containing supplement locked and out of reach.

  • Testing guides the plan. It tells you whether iron is needed, what amount makes sense, and when to retest.

What to do next

If your child has attention concerns, ask your health care provider whether a ferritin test makes sense alongside the CBC.

It also helps to bring:

  • A short list of the signs you've noticed

  • A few days of what your child typically eats and drinks

  • Any supplements they already take

How I support families in Barrie and across Ontario

I'm Dr. Yasmin Snippe, a children's health focused naturopathic doctor and registered nurse, practising at Rooted Naturopathic Clinic in Barrie. I also offer virtual visits across Ontario.

In my Children's ADHD Support Program, the first phase, Investigate, starts with a detailed nutrition assessment. We look at what your child eats, what labs make sense, and how to fill any gaps. (What to expect from an ADHD nutrition assessment) The program is designed to work alongside your child's medical team, not replace it.

Not sure where to start? Book a free 15-minute Meet & Greet and we'll talk through your child's needs together.

Frequently asked questions

Does low iron cause ADHD?

No study has shown that. Research, including a 2026 study, shows low iron stores are more common in some children with ADHD, but it can't show cause. Low iron is one piece of the picture worth checking.

Can my child have low iron if their blood count is normal?

Yes. Iron stores (ferritin) drop before hemoglobin does. A standard CBC can look normal while stores are already low, which is why ferritin is a separate test.

What ferritin level is too low for a child?

Lab ranges vary, and some list very low numbers as normal. The 2026 study used under 30 ng/mL to define low stores. Your child's provider can interpret the result alongside symptoms, diet and recent illness.

Should I give my child an iron supplement for ADHD?

Not without testing first. Too much iron can be harmful, and iron is a serious poisoning risk for young children. Testing shows whether iron is needed and what amount is safe.

What are the best iron-rich foods for kids?

Beef, chicken, eggs, lentils, beans, pumpkin seeds and iron-fortified cereals. Pair plant sources with vitamin C foods like berries or peppers, and serve milk between meals.

Do you see children with ADHD in Barrie?

Yes. Dr. Yasmin Snippe ND, RN offers in-person visits in Barrie and virtual visits across Ontario through her Children's ADHD Support Program, designed to work alongside your child's medical team.

Source: Serum ferritin and hematological indices in children with attention-deficit/hyperactivity disorder: a matched case-control study. BMC Pediatrics, 2026. PubMed 42928206

This article is for education only and isn't a substitute for individual medical advice. Speak with your child's health care provider before making changes.