Iron Deficiency Test: Do Your Symptoms Point to Low Iron?

Based on NIH Office of Dietary Supplements guidance · Last reviewed: July 15, 2026 · How we source our content

Iron deficiency is the most common nutritional deficiency on the planet — the WHO considers it the leading cause of anemia worldwide, and it's especially widespread among menstruating women, where studies regularly find a substantial share affected without knowing it. The tricky part: by the time a routine blood count flags anemia, your iron stores have usually been empty for a while. The symptoms start much earlier.

The symptoms — including the strange ones

The classic picture is fatigue you can't explain, pale skin, and getting winded on stairs that never used to bother you — all downstream of having less hemoglobin to carry oxygen. But iron deficiency also produces some oddly specific symptoms that most people never connect to a nutrient:

• Craving and chewing ice (pagophagia) — one of the most distinctive signs; some people also crave dirt, clay or raw starch (pica)
• Restless legs at night — an urge to move your legs that disrupts sleep; low iron is a well-documented contributor
• Brittle or spoon-shaped nails (koilonychia) — nails that thin, flatten, and eventually curve upward
• More hair in the brush and drain — diffuse shedding is a common early complaint, particularly in women
• Cracks at the corners of the mouth and a sore tongue
• Cold hands and feet, headaches, and trouble concentrating

Where the iron actually goes

Unlike vitamin D or B12, iron deficiency is usually a story about loss outpacing intake. Ask yourself which of these applies:

• Menstruation — the single biggest cause in younger women; heavier periods multiply the effect. Women aged 19–50 need 18 mg of iron daily versus just 8 mg for men, and diet often doesn't close that gap.
• Pregnancy — requirements jump to 27 mg/day to supply the placenta and a growing blood volume.
• Endurance training — runners lose iron through foot-strike damage to red blood cells, sweat, and exercise-induced gut losses.
• Regular blood donation — each donation removes roughly 200–250 mg of iron; generous donors often run their ferritin down.
• Plant-based eating — non-heme iron from plants is absorbed several times less efficiently than heme iron from meat and fish.
• Gut conditions and medications — celiac disease, inflammatory bowel disease, and long-term acid reducers all cut absorption.

In men and post-menopausal women, iron deficiency is uncommon enough that doctors treat it as a finding to investigate, not just correct — unexplained blood loss (often gastrointestinal) needs to be ruled out. That's another reason the right move is testing, not quietly supplementing.

Testing: ask about ferritin, not just "anemia"

Iron deficiency develops in stages. Ferritin — your storage iron — falls first, and fatigue, hair shedding and restless legs often begin here, while hemoglobin is still normal. Only later does a standard blood count turn abnormal. So if you get tested, make sure ferritin is on the order; a "normal" anemia screen alone can miss the early stage entirely.

Our free assessment helps you figure out whether that test is worth requesting. It weighs your symptoms against the loss factors above — and checks the alternatives, because unexplained fatigue is also the headline symptom of vitamin D and B12 deficiency. Two minutes of questions tells you which test to ask for first.

Eating for iron (once you know you need it)

Heme iron — red meat, poultry, fish — is absorbed several times better than non-heme iron from lentils, beans, spinach, tofu and fortified cereals. Three practical rules move the needle most: add vitamin C to plant-iron meals (bell peppers, citrus, tomatoes can multiply absorption), keep tea and coffee at least an hour away from iron-rich meals (their tannins and polyphenols block uptake), and don't take calcium supplements with iron. More detail lives in our nutrition guide's iron section.

Frequently asked questions