Iron Deficiency & Anemia in Women: The Most Overlooked Health Issue

A 38-year-old teacher came to me exhausted. Not the "I had a long day" kind of tired — the "I can't get through the afternoon without putting my head on my desk" kind. She'd been told by two different doctors that her labs were "normal." Her hemoglobin was 12.8 (technically normal). Her MCV was 84 (normal). But her ferritin? It was 8 ng/mL. She was profoundly iron-depleted, and nobody had checked the one test that would have caught it.

I'll be honest — iron deficiency in women is one of the most common yet most under-diagnosed conditions I see. The conventional threshold for ferritin ("normal" starts at 10–12 ng/mL in most lab ranges) is based on the level that prevents frank anemia, not the level needed for optimal function. In functional medicine, we know that symptoms of iron deficiency begin long before you become anemic (1).

Iron Deficiency vs. Iron Deficiency Anemia: A Critical Distinction

Most doctors screen for anemia with a CBC (complete blood count). If hemoglobin is above 12 g/dL, they call it normal and move on. But iron deficiency progresses through three stages:

1. Iron depletion: Ferritin drops (stores emptying), but hemoglobin and RBC indices are still normal. Symptoms already present.

2. Iron-deficient erythropoiesis: Iron supply to bone marrow is insufficient. Subtle lab changes begin (rising TIBC, dropping transferrin saturation).

3. Iron deficiency anemia: Hemoglobin drops below normal. This is the *end stage*, not the beginning.

Why Women Are Disproportionately Affected

• Menstruation: Women with regular periods lose 1–2 mg of iron daily during menstruation. Heavy periods (menorrhagia) can double or triple this.
• Pregnancy: Requires 500–800 mg of additional iron for expanded blood volume, placental development, and fetal needs.
• Postpartum: Blood loss during delivery + breastfeeding demands deplete stores rapidly.
• Dietary patterns: Women are more likely to follow plant-based or low-meat diets. Non-heme iron (plant sources) has 2–20% absorption vs. 15–35% for heme iron (animal sources).
• Gut health: H. pylori infection, celiac disease, SIBO, and low stomach acid (common with PPI use) all impair iron absorption.

The Symptoms Most Doctors Miss

Iron is involved in over 300 enzymatic reactions, not just oxygen transport. Deficiency affects:

Energy & Cognition:

• Profound fatigue disproportionate to activity level
• Brain fog and difficulty concentrating
• Poor memory and slow processing speed
• Inability to exercise at prior capacity

Mood & Nervous System:

• Anxiety (iron is required for dopamine and serotonin synthesis)
• Restless leg syndrome (one of the most specific symptoms — present in >25% of iron-deficient women)
• Irritability and mood instability
• Insomnia

Hair, Skin & Nails:

• Hair loss and thinning (ferritin <40 impairs hair follicle function)
• Brittle nails and koilonychia (spoon nails)
• Pale skin and mucous membranes
• Cold intolerance

Immune Function:

• Frequent infections
• Slow wound healing
• Recurrent mouth ulcers

Thyroid Function:

• Iron is required for thyroid peroxidase (the enzyme that makes thyroid hormones). Iron deficiency causes secondary hypothyroidism that won't respond to thyroid medication alone.

The Right Lab Workup

Don't settle for just a CBC. Here's the complete iron panel:

Root-Cause Investigation

When iron is low, I don't just supplement — I investigate *why*:

• Heavy menstrual bleeding: Evaluate for fibroids, PCOS, endometriosis, or clotting disorders
• Poor absorption: Test for celiac disease, H. pylori, low stomach acid, SIBO
• Increased demand: Pregnancy, postpartum, intense athletic training
• Chronic blood loss: GI sources (occult bleeding from polyps, ulcers, IBD)
• Dietary insufficiency: Vegetarian/vegan diets without adequate planning

Treatment: Beyond Just Taking Iron Pills

Oral Supplementation

• Iron bisglycinate (chelated): Best tolerated form, 25–50 mg elemental iron daily. Significantly less GI side effects than ferrous sulfate.
• Take on empty stomach (or with vitamin C) for maximum absorption
• Avoid taking with calcium, coffee, tea, or dairy (all inhibit absorption)
• Every-other-day dosing: Recent research shows that alternate-day iron dosing may actually improve absorption due to hepcidin cycling (2). The body absorbs a higher percentage of iron when given every 48 hours vs. daily.
• Duration: Most women need 3–6 months of supplementation to replenish stores

Dietary Optimization

Heme iron sources (best absorbed):

• Red meat, liver, organ meats
• Dark poultry meat
• Oysters, clams, mussels

Enhancers (pair with iron-rich foods):

• Vitamin C (bell peppers, citrus, strawberries)
• Cooking in cast iron (can increase iron content of acidic foods by 2–3x)

Inhibitors (separate from iron meals by 2+ hours):

• Coffee and tea (tannins)
• Calcium supplements
• Phytates (whole grains, legumes — cooking/soaking reduces these)

When IV Iron Is Needed

Oral iron is insufficient when:

• Ferritin is <15 with symptomatic anemia
• There's documented malabsorption (celiac, IBD, post-bariatric surgery)
• Oral supplementation fails after 3 months of proper dosing
• There's an immediate need (late pregnancy, pre-surgical)

IV iron infusion (ferric carboxymaltose or iron sucrose) can replenish stores in 1–2 sessions, bypassing absorption issues entirely.