Ferritin and hair loss in London: the number your GP is reading wrong

Every London trichologist has this conversation weekly: patient comes in with three months of shedding, has a printed set of blood results from their GP, and everything is 'normal'. The ferritin is 22. Their GP has told them not to worry. Their hair is falling out. This guide is why the conversation matters.

What ferritin actually is

Ferritin is the storage form of iron — the body's iron reserve, held mostly in liver and bone marrow. Serum ferritin reflects those stores. Haemoglobin measures circulating iron in red cells; you can have depleted ferritin while haemoglobin remains normal, and still have iron-related hair loss. Hair loss frequently precedes anaemia by months or years.

Hair follicles are extremely metabolically active during anagen and are exquisitely sensitive to iron availability. Without enough iron, follicles shift into telogen earlier (telogen effluvium) and, in patients with underlying pattern predisposition, miniaturisation accelerates.

The number that matters

The lab reference range for ferritin was designed to detect anaemia risk, not to optimise hair growth. In London, most labs flag ferritin <15 μg/L as low. But hair studies consistently show measurable benefit up to 70 μg/L, and some research groups argue for higher (>100) in active regrowth.

• <15 μg/L: iron deficient. Universally symptomatic. Treat aggressively.
• 15–30 μg/L: subclinical deficiency. Hair usually affected. Treat.
• 30–70 μg/L: 'grey zone'. Hair loss frequently improves with supplementation to >70.
• 70–150 μg/L: hair-optimal.
• >200 μg/L: consider iron overload (haemochromatosis), inflammation or excess supplementation.

Supplementation done right

The single most common mistake is prescribing ferrous sulphate 200 mg three times daily and stopping when the patient can't tolerate the GI side effects. Two things fix this:

• Alternate-day dosing. Recent physiology work shows iron absorption is blocked by hepcidin for 24 hours after each dose — daily dosing absorbs no better (and often less) than alternate-day. Take Monday, Wednesday, Friday.
• The right formulation. Ferrous sulphate 200 mg or ferrous fumarate 210 mg are cheapest and effective but often GI-difficult. Iron bisglycinate 25–50 mg elemental is much better tolerated and clinically effective. 'Gentle iron', Solgar, Thorne and Spatone are London-available options.
• Take with vitamin C (50–100 mg) or a small glass of orange juice — doubles absorption.
• Take on empty stomach where tolerated, or with light snack.
• Avoid within 2 hours of tea, coffee, dairy, calcium supplements, antacids — all block absorption.
• Re-test at 3 months. Expect ferritin to rise 20–40 μg/L. If unchanged: absorption problem, ongoing loss, or non-compliance.

When oral iron isn't working

If a patient is on adequate oral iron for 3 months and ferritin hasn't moved, three things are usually happening:

• Ongoing loss — heavy menstrual bleeding is the commonest cause in London women. Gynaecology review.
• Malabsorption — coeliac disease and H. pylori are the classic misses. Coeliac serology, upper GI symptoms review.
• Occult GI blood loss — polyps, colitis, rarely malignancy. Warrants GI referral, particularly in men and post-menopausal women.
• Chronic inflammation raising ferritin artificially — check CRP alongside; a 'normal' ferritin with high CRP can hide true deficiency.

IV iron and when it makes sense

For patients who cannot tolerate oral iron, do not absorb it, or need rapid correction, IV iron (ferric carboxymaltose — Ferinject; iron isomaltoside — Monofer) is safe and effective. NHS access is possible via gynaecology or gastroenterology in appropriate cases. Private London IV iron infusions run £400–£800 per session; one session usually raises ferritin by 100–300 μg/L within weeks.

IV iron is not a shortcut to bypass workup — a menorrhagic patient given Ferinject without gynaecological management will re-deplete within months. Treat the cause, then top up.