Iron is one of those nutrients we take for granted until we don't have enough of it. It carries oxygen in our red blood cells, fuels mitochondria in every tissue, supports immune function, and helps make the neurotransmitters that regulate mood and attention. When iron stores fall, the consequences are quietly systemic — and they accumulate long before haemoglobin ever drops into the "anemic" range.
That delay is the source of an enormous diagnostic blind spot. Most patients with iron deficiency in Canada are told their bloodwork is "fine" because their haemoglobin is normal. Their ferritin — the actual measure of iron stores — was never checked, or was checked and dismissed because the lab's reference range starts at 15 ng/mL, even though most internists agree that's far below what a healthy adult should run.
The symptoms patients describe
In a typical Internal Medicine consultation for iron deficiency, the symptoms that come up are remarkably consistent across patients — and remarkably under-recognised in primary care:
- Persistent fatigue that doesn't improve with rest, sleep, or a holiday.
- Brain fog — difficulty concentrating, word-finding problems, mental slowness — that the patient often attributes to stress or burnout.
- Hair shedding, particularly diffuse loss across the scalp rather than patchy.
- Restless legs at night, or an urge to move legs that interferes with sleep.
- Breathlessness on minimal exertion — climbing stairs, carrying groceries.
- Cold hands and feet, even in warm rooms.
- Brittle nails or unusual nail spooning.
- Headaches, particularly with exertion.
- Low mood, anxiety, or reduced motivation — particularly with no obvious life trigger.
- Pica — unusual cravings for ice, dirt, or starch (a classic iron-deficiency sign).
None of these are pathognomonic for iron deficiency on their own. But when several appear together in a patient with risk factors — heavy menstrual periods, vegetarian or vegan diet, pregnancy or post-partum, GI conditions, frequent blood donation — the index of suspicion should be high.
Why the standard work-up misses it
Iron deficiency is the most common nutritional deficiency in the world. By global estimates it affects roughly one in four people, with women of reproductive age disproportionately represented. Despite that, the workflow in many primary-care settings is the same as it was thirty years ago: order a CBC, look at the haemoglobin, and call it done.
The problem is that haemoglobin is the last thing to fall. Long before red blood cell production is compromised, the body has already drained its ferritin stores, started recycling iron more aggressively, and altered transferrin saturation. Patients in this stage — iron deficiency without anemia — can have years of symptoms while their haemoglobin sits comfortably above the cutoff.
If you only check haemoglobin, you will miss the majority of patients with iron deficiency. Ferritin and iron saturation are not optional in this work-up — they are the work-up.
What a proper iron panel looks like
At MED1, the iron work-up is structured the same way for every patient:
- Complete blood count (CBC) with red cell indices (MCV, MCH, MCHC).
- Serum ferritin — the single most useful test for iron stores.
- Serum iron and total iron binding capacity (TIBC).
- Transferrin saturation, calculated from serum iron and TIBC.
- Reticulocyte count in selected cases.
A ferritin below about 30 ng/mL in a non-inflamed patient is, in our practice, sufficient evidence to consider iron deficiency and start treatment. Many specialists treat at ferritins up to 50 ng/mL in symptomatic patients — the literature increasingly supports this threshold over the older "is it below 15?" approach.
What you can do
If the symptoms above describe your experience and your bloodwork has been limited to a CBC, ask your family physician for a full iron panel — specifically including ferritin and transferrin saturation. If you have already been told your iron is "fine" but your ferritin is below 50 with persistent symptoms, a specialist consultation can clarify whether treatment is appropriate.
If you are a physician with a patient who fits this picture, our Internal Medicine Clinic exists specifically to compress this work-up. Most referred patients are seen within the same week, with a treatment plan returned to your office shortly after.
Iron deficiency is one of the most rewarding conditions to treat in medicine: most patients feel meaningfully better within a week of restoring their iron, and many describe it as feeling like themselves again for the first time in years. The hard part has never been the treatment. It has been getting the diagnosis seen in the first place.