Ferritin: Why This Iron Marker Matters Beyond Anaemia

Ferritin is your body's iron storage protein. Think of it as your iron savings account—while haemoglobin represents the iron currently in use, ferritin shows how much you have in reserve.

When ferritin drops, your body has less iron to draw upon for critical functions, even if your haemoglobin remains "normal."

Here's where it gets frustrating. Most labs list ferritin as "normal" anywhere from 15-200 ng/mL for women and 30-400 ng/mL for men. That's an enormous range.

A woman with a ferritin of 18 ng/mL is technically "normal" but is likely experiencing significant symptoms:

• Persistent fatigue that sleep doesn't fix
• Exercise intolerance
• Shortness of breath on exertion
• Brain fog and poor concentration
• Restless legs
• Hair loss

Functional ranges supported by research suggest:

• Optimal: 70-100 ng/mL
• Acceptable: 50-70 ng/mL
• Low (symptomatic): Below 50 ng/mL
• Deficient: Below 30 ng/mL

Many practitioners won't address ferritin until it drops below 15—by which point you may have been suffering for months or years.

Iron is essential for:

• Oxygen transport — Haemoglobin carries oxygen to tissues
• Mitochondrial function — Iron is a cofactor in energy production
• Collagen synthesis — Critical for tissue repair
• Immune function — White blood cells need iron
• Neurotransmitter production — Dopamine synthesis requires iron

If you're recovering from injury, training hard, or dealing with chronic fatigue, suboptimal ferritin will slow you down.

• Inadequate dietary intake — Particularly in vegetarians/vegans
• Poor absorption — Gut issues, low stomach acid, coeliac disease
• Chronic blood loss — Heavy menstrual periods, GI bleeding
• High demand states — Pregnancy, intense training, growth periods
• Inflammation — Can sequester iron away from circulation

Ferritin is also an acute phase reactant—it rises during inflammation. This means someone with chronic inflammation might show "normal" ferritin while actually being iron deficient.

This is why we look at ferritin alongside other markers like CRP and a full blood count to get the complete picture.

If ferritin is low, the approach depends on the cause:

• Dietary optimisation — Haem iron sources, vitamin C pairing
• Addressing absorption issues — Gut health, stomach acid support
• Targeted supplementation — The right form matters (some are poorly tolerated)
• Treating underlying causes — Identifying and addressing blood loss

At Metabolic Physio, ferritin is a core marker in our Metabolic Audit. We interpret it functionally—not just checking if you're anaemic, but whether you have the reserves to actually thrive.