Iron Deficiency

Iron deficiency means your body’s iron stores have run low. Iron makes haemoglobin, which carries oxygen in the blood, so low stores can leave you tired and short of breath. It is common in Canada, and often a clue rather than a diagnosis.

What iron deficiency is, and what it is not

It is not the same as anemia. Anemia means your haemoglobin has fallen; iron deficiency means the stores behind it are low. You can have low stores with a normal haemoglobin, called non-anemic iron deficiency, and a 2025 CMAJ review says both cause substantial morbidity.

It is also not simply about diet. In adults it is often the first sign of bleeding, usually from the digestive tract or heavy periods. And more iron is not automatically better: the national survey that found deficiency in 7% of Canadians found elevated iron stores in 17.2%, mostly adult men.

Signs and symptoms

• Tiredness that rest does not fix, and less stamina than usual
• Shortness of breath or a pounding heart on exertion, or dizziness on standing
• Trouble concentrating, low mood, or a foggy feeling
• Restless, uncomfortable legs, especially at night
• Craving or chewing non-food things such as ice, called pica

Symptoms build slowly and can be vague. Pale skin and headaches usually appear once anemia develops.

What raises the risk

Some things cannot be changed:

• Menstruation, which causes iron loss monthly, with heavier bleeding raising risk further
• Pregnancy. In an Ontario study cited by CMAJ, 53% of pregnant outpatients had iron deficiency
• Conditions that reduce absorption, including coeliac disease and previous bariatric surgery

Others can often be worked on, usually with support from a health care team:

• Bleeding from the digestive tract, which the BC guideline names as a primary cause in adults: peptic ulcers, inflammatory bowel disease or colorectal cancer
• Regular whole blood donation. Canadian Blood Services began selective ferritin testing in 2023 because donating costs iron
• Dietary iron intake and absorption, which a clinician or dietitian can review

How iron deficiency is diagnosed in Canada

Iron deficiency is found with blood tests: a complete blood count and serum ferritin, which the BC guideline calls the test of choice. Finding low iron is the start of the assessment, not the end. The BC guideline sets out when a source of bleeding is looked for: in adult men and postmenopausal women with unexplained iron deficiency, in premenopausal women without heavy periods, and whenever there is new bleeding from the gut. That can mean referral for endoscopy or colonoscopy.

Treatment and day-to-day management

Clinical research for Iron Deficiency is enrolling. See the current studies ↓

Care has two halves: restoring iron, and dealing with what caused the loss. A health care team may discuss:

• Investigating and treating the cause, which in adults may mean looking at the digestive tract or at heavy periods
• Oral iron, which Canadian guidance describes as first-line, usually an iron salt such as ferrous sulfate
• Intravenous iron, used when oral iron is not tolerated or has not worked, or when absorption is impaired
• Reducing menstrual blood loss, using options such as tranexamic acid, oral contraception or a progesterone-releasing intrauterine device

Iron is a medicine, not a default. What fits your situation is a decision for you and your own clinician.

When to talk to a doctor

• Chest pain, severe shortness of breath, fainting or a racing heart needs emergency assessment. Call 911 or go to an emergency department.
• Black or tarry stools, blood in the stool, vomiting blood, or blood in the urine needs urgent assessment, because these point to bleeding that must be found.
• Iron deficiency newly found in an adult man, or a woman past menopause, is when the BC guideline says a gut source of bleeding is investigated.

Why clinical research matters for iron deficiency

The national figure is unsettled: the Canadian Health Measures Survey estimate moved from 7% to 10.5% or 12.6% depending on how inflammation was handled, and the authors said the methods need further research. Recognition is patchy: an Ontario screening study found non-anemic iron deficiency in 38% of nonpregnant females screened. Open questions include who should be screened, whether treating low stores before anemia develops improves fatigue, and how oral and intravenous iron compare.

Clinical studies are how those questions get answered. Taking part is voluntary, informed consent comes first, and you can stop at any time without affecting your regular care. No one can say whether a study will help you personally.

Learn more from Canadian sources

• BC Guidelines: iron deficiency
• Statistics Canada: iron sufficiency
• Canadian Blood Services: ferritin testing
• HealthLink BC: iron deficiency anemia