Iron Deficiency

The answer first

Iron deficiency is the commonest cause of anaemia in the world, the most over-investigated-yet-under-diagnosed number on the FBC, and — in an adult man or postmenopausal woman — a malignancy signal first and a haematinic deficiency second ^{[1] [2]}. Three rules carry you through almost every DWE question and every clinic letter:

1. Diagnose with ferritin and TSAT together, and never trust ferritin alone in inflammation. Ferritin below about 30 µg/L confirms iron deficiency; but ferritin is an acute phase reactant, so in any inflamed patient a "normal" ferritin means nothing — read it beside CRP and transferrin saturation, where TSAT below 20% unmasks deficiency the ferritin is hiding ^{[1] [5]}.
2. Find the cause, and let the demographics choose the scope. Menstrual loss explains iron deficiency in a premenopausal woman until you prove otherwise; in men and postmenopausal women, occult GI blood loss is assumed and bidirectional endoscopy is the standard of care — iron tablets without gastroscopy and colonoscopy is the classic examination and medicolegal failure ^{[5] [6]}.
3. Replace iron physiologically, and match the route to the gut. Oral iron first for most — once daily or alternate days, because each dose spikes hepcidin and blocks the next one. Intravenous iron when the gut cannot absorb it or the loss outruns it: active IBD, bariatric surgery, CKD, heart failure, intolerance or non-response ^{[11] [12] [14]}.

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References23ShowHide

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