Ferritin & iron studies
Shows how much iron your body has in storage - which can run low long before a blood count shows anemia.
TypeBlood test
HowStandard blood draw. Morning is best.
How oftenBaseline, then yearly if you’re at risk or supplementing.
BeforeAvoid iron supplements for 24 hours before.
WhoPeople who menstruate, athletes, plant-based eaters, blood donors and anyone always tired.
Why a “normal blood count” can miss low iron
Your body uses stored iron first. Only when stores run out does hemoglobin fall and anemia show up. Ferritin measures the stores - so it can reveal a problem months earlier.
Full stores
“Am I OK?”
Ferritin and hemoglobin both normal. Plenty in reserve.
Healthy
Running low
“Why am I tired if my bloods are normal?”
Ferritin falls, hemoglobin still normal. Fatigue, hair shedding, poor exercise tolerance and restless legs can already appear.
Often missed
Anemia
“Now my blood count is low.”
Stores are empty. Hemoglobin drops and symptoms get worse.
Late stage
If your ferritin is low
01
Find the cause
Heavy periods, diet, gut absorption or blood loss - each needs a different fix.
02
Treat, then retest
Recheck after 2–3 months so supplements have an endpoint.
03
Don’t overdo it
Too much iron is harmful - only supplement when low.
04
Pair with vitamin C
It helps absorption; tea and coffee reduce it.
A high ferritin can also be meaningful - worth discussing with your provider.
Is it right for you?
Worth considering if…
- You’re tired, breathless on exertion or losing hair.
- You have heavy periods, give blood often or train hard.
- You eat little or no red meat.
- You have restless legs.
A better option if…
- You’re acutely unwell - ferritin rises with inflammation and can look falsely normal; retest when well or add transferrin saturation.
How it’s measured
Ferritin
Your iron stores.
Iron studies
Serum iron, transferrin and transferrin saturation - how much iron is available to use.
With a CBC
Shows whether anemia has already developed.
The full picture
What is it?
A protein that stores iron; blood levels mirror your body’s reserves.
What type of test is it?
A blood biomarker panel.
What does it measure?
Ferritin, serum iron, transferrin and transferrin saturation.
Why might someone consider it?
Low iron is one of the most common causes of tiredness and is easy to treat.
Who is it most relevant for?
People who menstruate, athletes, vegetarians, blood donors and anyone with fatigue.
How is it performed?
A routine blood draw.
How often might it be considered?
Yearly if at risk; 2–3 months after starting treatment.
What can the result help you understand?
Whether your iron stores are low, normal or too high.
What are its limitations?
Inflammation raises ferritin and can mask low stores.
What should it be viewed with?
CBC, B12, folate, thyroid, periods and diet.
Where to get it
Through your provider
The simplest route - often covered when there’s a clear reason.
Lab services
e.g. Quest Diagnostics, Labcorp.
Direct-to-consumer panels
e.g. Function Health, InsideTracker.
Names are examples only, not endorsements. Your provider can often order the same test - and help interpret it.
Connected to
Questions to ask your provider
- Is my ferritin low even if my blood count is normal?
- What’s causing my low iron?
- When should I retest?
Ziva Health
One test is a snapshot. Ziva shows the whole story.
Ziva brings your lab results, wearables and daily readings together - and Isabella tells you what’s changing and what to ask your provider next.
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Being listed doesn’t mean everyone needs this test. Educational only — not medical advice. Results should be interpreted with a qualified clinician. ← Back to Know What to Test