Iron Deficiency in Women: Why It's So Common and What to Do About It

You're exhausted all the time. Not the kind of tired that sleep fixes — the kind that lives in your bones. You've been told your blood work is "normal," but you still feel like you're running on empty. Your hair is thinning. You're short of breath climbing stairs. You crave ice or dirt (yes, really). You bruise easily and your nails are brittle.

Your doctor checked your hemoglobin and said you're not anemic. Case closed. Except it shouldn't be, because iron deficiency can wreck your quality of life long before it shows up as anemia on a standard complete blood count.

Iron Deficiency vs. Iron Deficiency Anemia

This distinction matters enormously and is missed constantly.

Iron deficiency means your body's iron stores are depleted. Your ferritin — the protein that stores iron — is low. You may already be symptomatic. But your hemoglobin might still be in the "normal" range because your body is pulling iron from stores to maintain red blood cell production. You're running on reserves, and the tank is nearly empty, but the car is still technically moving.

Iron deficiency anemia means your stores are so depleted that your body can no longer produce enough hemoglobin. Your red blood cells become small (microcytic) and pale (hypochromic). This is the late stage — you've been iron deficient for a while before reaching this point.

The problem: most standard blood panels only check hemoglobin and hematocrit. If those are normal, many providers declare you "not anemic" and move on. They don't check ferritin, and you don't get treated, even though iron deficiency without anemia causes real symptoms.

Why Women Are Disproportionately Affected

Iron deficiency is the most common nutritional deficiency in the world, and premenopausal women are at the highest risk because of a simple math problem: they lose iron through menstruation and often don't replace enough through diet.

The numbers: The average menstrual cycle loses about 30-40 mL of blood, containing approximately 15-20 mg of iron. Women with heavy menstrual bleeding (menorrhagia) — defined as losing more than 80 mL per cycle — can lose significantly more. Meanwhile, the typical American diet provides about 10-15 mg of dietary iron per day, and only 10-15% of that is actually absorbed.

Other risk factors that compound the problem:

• Pregnancy — Iron requirements roughly double during pregnancy
• Vegetarian or vegan diets — Non-heme iron (from plants) is absorbed at 2-20% compared to 15-35% for heme iron (from animal sources)
• Endometriosis or fibroids — Both can cause heavy menstrual bleeding
• Frequent blood donation — Each donation removes approximately 200-250 mg of iron
• Celiac disease or inflammatory bowel disease — Impaired iron absorption
• Bariatric surgery — Reduced absorptive surface area
• Intense exercise — Especially distance running (foot-strike hemolysis, GI blood loss, inflammation-related hepcidin elevation)
• Chronic NSAID use — Can cause occult GI bleeding

Symptoms You Might Not Connect to Iron

The classic symptom is fatigue, but iron deficiency causes a constellation of symptoms that many women attribute to stress, aging, or "just being tired":

• Fatigue and weakness — Disproportionate to activity level
• Brain fog and difficulty concentrating — Iron is essential for neurotransmitter synthesis
• Hair loss — Particularly diffuse thinning; ferritin below 30-40 is associated with hair shedding
• Restless legs syndrome — Strong association with low ferritin, even without anemia
• Shortness of breath — During exertion, sometimes even at rest
• Heart palpitations — The heart compensates for reduced oxygen-carrying capacity
• Pale skin and mucous membranes — Check inside the lower eyelid
• Cold intolerance — Iron affects thermoregulation
• Brittle nails or spoon-shaped nails (koilonychia)
• Pica — Craving non-food substances like ice (pagophagia), clay, starch, or dirt. This is surprisingly common and often unrecognized.
• Glossitis — Smooth, sore tongue
• Angular cheilitis — Cracking at the corners of the mouth
• Frequent infections — Iron plays a role in immune function
• Depression and anxiety — Iron is involved in dopamine and serotonin synthesis

What Your Labs Should Include

If you suspect iron deficiency, request these specific tests:

• Ferritin — The single most useful test for iron stores. Below 30 ng/mL is deficient (despite many lab ranges listing "normal" as low as 10-15). Below 50 is suboptimal for symptomatic patients. Ferritin is also an acute phase reactant, meaning it can be falsely elevated during infection, inflammation, or liver disease.
• Serum iron — The amount of iron circulating in your blood. Less useful alone because it fluctuates throughout the day.
• TIBC (Total Iron-Binding Capacity) — Measures how much transferrin (the iron transport protein) is available. High TIBC suggests iron deficiency (your body is making more transport protein because it needs more iron).
• Transferrin saturation — Calculated from serum iron and TIBC. Below 20% suggests iron deficiency.
• CBC with differential — To check hemoglobin, MCV (mean corpuscular volume — low in iron deficiency anemia), and reticulocyte count.
• CRP or ESR — If ferritin is normal but symptoms are suggestive, an inflammatory marker helps determine if ferritin is falsely elevated.

At CORAL, Dr. Kim includes a comprehensive iron panel in evaluations for fatigue, hair loss, and related symptoms — not just a hemoglobin check.

Treatment: How to Actually Replete Iron

Oral Iron Supplementation

First-line treatment for most patients. The key details matter:

• Ferrous sulfate 325 mg (65 mg elemental iron) — the most common and most studied formulation
• Every other day dosing — Recent research shows that taking iron every other day rather than daily actually improves absorption. Daily dosing increases hepcidin (a hormone that blocks iron absorption), so the second dose in a day is poorly absorbed. Every-other-day dosing keeps hepcidin low.
• Take on an empty stomach with vitamin C (a glass of orange juice works) to enhance absorption
• Avoid taking with calcium supplements, dairy, coffee, tea, antacids, or proton pump inhibitors — all of these reduce absorption
• Duration — Typically 3-6 months to replete stores. Don't stop when you feel better — continue until ferritin is above 50-100 ng/mL.

GI side effects are the main reason people stop taking iron. Strategies to reduce them:

• Try every-other-day dosing
• Take with food (reduces absorption but improves tolerance)
• Switch formulations — ferrous bisglycinate (iron glycinate) is gentler on the stomach with comparable absorption
• Liquid iron formulations may be better tolerated
• Start at a lower dose and increase gradually

IV Iron Infusion

For patients who can't tolerate oral iron, don't absorb it well, or need rapid repletion:

• Ferric carboxymaltose (Injectafer) — Can deliver 750-1,000 mg in a single infusion
• Iron sucrose (Venofer) — Typically given as a series of smaller infusions
• Ferumoxytol (Feraheme) — Another single-dose option

IV iron is appropriate when:

• Oral iron is not tolerated despite trying multiple formulations
• Malabsorption conditions prevent adequate oral uptake (celiac, IBD, bariatric surgery)
• Ongoing blood loss exceeds what oral iron can replace
• Hemoglobin is critically low and rapid correction is needed
• Ferritin remains low despite months of oral supplementation

Address the Underlying Cause

Iron supplementation without addressing why you're deficient is like bailing water without fixing the leak:

• Heavy periods — Evaluate for fibroids, endometriosis, coagulopathy. Consider hormonal management to reduce menstrual blood loss.
• GI blood loss — Occult blood testing, consider endoscopy/colonoscopy if no obvious gynecological cause
• Celiac disease — Screen with tissue transglutaminase antibody (tTG-IgA) if malabsorption suspected
• Diet — Assess dietary iron intake, especially in vegetarians/vegans

Monitoring Treatment

After starting iron replacement:

• Recheck ferritin at 8-12 weeks — You should see improvement
• Symptom improvement — Some symptoms (fatigue, brain fog) may improve within weeks; others (hair regrowth) take months
• Reticulocyte count — A rise within 1-2 weeks indicates the bone marrow is responding
• Goal ferritin — Above 50-100 ng/mL for most patients, especially those with hair loss or restless legs

Don't Accept "Normal" When You Feel Terrible

The reference ranges on lab reports are population-based statistics, not clinical guidelines. A ferritin of 12 ng/mL is technically within the "normal range" at many labs, but it is not normal for optimal function. If you're symptomatic with a low-normal ferritin, you deserve treatment — not dismissal.

[Schedule a visit at coral.clinic/start](https://coral.clinic/start). Dr. Kim takes iron deficiency seriously, orders the right tests, and creates a treatment plan that actually repletes your stores — not just checks a box on your lab report.