- Ferritin is your iron savings account. It can run low for months before hemoglobin drops.
- The most common signs are fatigue, hair shedding, restless legs, brain fog and craving ice.
- A simple blood test confirms it, and levels usually recover within a few months of treatment.
You can feel drained, foggy and short of breath on the stairs while your blood count still looks normal. Low ferritin is one of the most common reasons, especially for women and endurance athletes.
Insyght tests ferritin, iron, TIBC and your full blood count in one draw, reviewed by a physician. $199 a year.
What low ferritin means
Ferritin is the protein that stores iron. When you use more iron than you take in, your body draws down these stores first. Only after they're nearly empty does hemoglobin fall and anemia appear.
Symptoms of low ferritin
Early signs (often before anemia)
- Tiredness that sleep doesn't fix
- Hair thinning or extra shedding
- Restless legs, especially at night
- Brain fog and trouble focusing
- Lower exercise tolerance or slower recovery
- Craving ice, a very specific sign
Later signs (as anemia develops)
- Shortness of breath on exertion
- Pale skin, gums or inner eyelids
- Fast or pounding heartbeat
- Dizziness when standing
- Cold hands and feet
- Brittle or spoon-shaped nails
Ferritin levels at a glance
| Ferritin (ng/mL) | What it usually means |
|---|---|
| Below 15 | Iron stores depleted; iron deficiency confirmed |
| 15 to 30 | Low stores; iron deficiency likely |
| 30 to 50 | Borderline; symptoms possible, especially in women |
| Within lab range | Adequate stores, unless inflammation is raising ferritin |
Ferritin rises with inflammation, so a "normal" value can hide low iron. That's why Insyght reads it alongside hs-CRP.
What causes low ferritin
- Blood loss: heavy periods, frequent blood donation, or hidden bleeding in the gut
- Low intake: plant-based diets or low red meat intake
- Poor absorption: celiac disease, low stomach acid, acid-reducing medications or bariatric surgery
- Higher demand: pregnancy, growth spurts and endurance training
Unexplained low ferritin in men or after menopause should always be checked by a physician, since it can signal gut bleeding.
Iron-rich foods
| Food | Serving | Iron (mg) | Type |
|---|---|---|---|
| Fortified breakfast cereal | 1 serving | Up to 18 | Non-heme |
| Oysters | 3 oz | 8 | Heme |
| White beans | 1 cup | 8 | Non-heme |
| Lentils, cooked | ½ cup | 3 | Non-heme |
| Spinach, boiled | ½ cup | 3 | Non-heme |
| Tofu, firm | ½ cup | 3 | Non-heme |
| Beef | 3 oz | 2 | Heme |
Heme iron from animal foods absorbs best. Pair plant iron with vitamin C, and keep coffee and tea away from iron-rich meals.
When to see your physician
See a physician if you have symptoms and a ferritin below 30 ng/mL, or if your level keeps falling. They'll look for the cause and decide whether you need oral or IV iron. Don't start high-dose iron without testing; too much iron can harm your liver and heart.
Frequently asked questions
Can you have low ferritin with normal hemoglobin?
How long does it take to raise ferritin?
Does low ferritin cause hair loss?
Insyght measures ferritin, iron, TIBC, hs-CRP and 100+ more data points, so you know whether iron is really the problem. $199 a year, HSA/FSA often eligible.
Keep reading
How we read 100+ biomarkers against optimal, not just the population average.
The panelWhat we testEvery biomarker in the Insyght Core Panel, across 10 body systems.
60 secondsThe Baseline CheckEight questions to see which of your systems deserves a closer look.
