Iron Deficiency in Women: Symptoms, Testing, and How to Restore Your Levels

Iron deficiency is the most common nutritional deficiency globally, and women are disproportionately affected due to menstrual blood loss. Yet it is frequently missed because standard testing measures serum ferritin or haemoglobin at thresholds set too low to capture functional deficiency, and symptoms are attributed to stress, depression, or "just being tired."

Why Iron Matters

Iron is required for haemoglobin synthesis (oxygen transport), mitochondrial energy production, thyroid hormone synthesis (thyroid function), neurotransmitter production (dopamine, serotonin), DNA synthesis, and immune function. When iron is depleted, essentially every system in the body is impaired.

Symptoms of Iron Deficiency

• Fatigue and low energy, often described as bone-deep

• Brain fog, poor concentration, and impaired memory

• Cold hands and feet

• Pale skin, pale inner eyelids

• Brittle nails, spoon-shaped nails

• Hair loss or shedding

• Restless legs syndrome

• Headaches

• Shortness of breath on exertion

• Worsening of anxiety and mood symptoms

• Impaired athletic performance

Iron Deficiency vs Anaemia

Iron deficiency exists on a spectrum. Iron deficiency anaemia (IDA) is the final stage, where haemoglobin falls below threshold and red blood cell production is affected. But symptoms of impaired function occur earlier, at the iron depletion and iron deficiency without anaemia stages, when ferritin is low and transferrin saturation is falling but haemoglobin is still "normal."

Functional iron deficiency begins when ferritin falls below 30 mcg/L in most people, despite a laboratory "normal" range extending down to 12 to 15 mcg/L in many labs.

Testing Iron Status Properly

Serum ferritin alone is inadequate. Comprehensive iron studies include:

• Serum ferritin (storage iron, target 70 to 100 mcg/L for women with symptoms)

• Serum iron

• Transferrin saturation (percentage)

• Total iron binding capacity (TIBC)

• Full blood count (haemoglobin, MCV, MCH)

• Reticulocyte count (iron-deficient erythropoiesis marker)

Ferritin is also an acute phase reactant: it rises with inflammation, masking true iron depletion. CRP (inflammatory marker) should be checked alongside ferritin. See the full article on functional testing.

Causes of Iron Deficiency in Women

• Menstrual blood loss (the primary cause in premenopausal women)

• Heavy periods associated with oestrogen dominance, fibroids, or endometriosis

• Poor dietary intake (low red meat, vegetarian/vegan diets without careful iron planning)

• Impaired absorption: low stomach acid, intestinal permeability, SIBO, coeliac disease

• Chronic inflammation (hepcidin blocks iron absorption)

Repleting Iron Effectively

Dietary Iron

Haem iron from red meat, poultry, and fish is the most bioavailable form (15 to 35 percent absorption). Non-haem iron from legumes, fortified foods, and leafy greens has 2 to 20 percent absorption, depending on vitamin C co-ingestion and inhibitors present.

Vitamin C with Iron-Rich Meals

Vitamin C converts ferric to ferrous iron and can increase non-haem iron absorption by 2 to 3-fold. A small glass of orange juice, a portion of capsicum, or a kiwifruit alongside iron-rich foods is a practical strategy.

Avoid Inhibitors at Iron Meals

Tea, coffee, calcium, and phytates (whole grains, legumes) reduce iron absorption. Timing these away from iron-rich meals or iron supplements optimises absorption.

Supplemental Iron

When dietary iron is insufficient to correct deficiency, supplementation is required. Iron bisglycinate (ferrous bisglycinate) is the most tolerable and well-absorbed form, with significantly less gastrointestinal side effects than ferrous sulphate. Dosing and duration should be guided by clinical assessment.

Exhausted despite sleeping enough and told your bloods are normal?

Book a Clinical Case Assessment with Kirstie to investigate whether low-grade iron deficiency is part of your picture.

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