Iron Deficiency in Adult Males

Primary Causes

In adult males with mild iron deficiency, gastrointestinal blood loss is the predominant mechanism and requires urgent investigation to exclude malignancy, even in the complete absence of GI symptoms 1, 2
Approximately one-third of men presenting with iron deficiency have an underlying pathological GI abnormality, and roughly one-third of these prove to be malignancies 3
Bidirectional endoscopy (gastroscopy and colonoscopy) should be performed as first-line investigation in all adult males with newly diagnosed iron deficiency, regardless of symptom absence 1, 3

Celiac disease accounts for 3-5% of all iron deficiency cases and must be screened for in every male patient with unexplained iron deficiency 1, 2, 3, 4
Screen with tissue transglutaminase antibody, and obtain duodenal biopsies during upper endoscopy even if serology is negative but clinical suspicion remains 2, 3
Chronic NSAID use causes occult gastrointestinal blood loss even without overt bleeding symptoms or ulceration 2
Explicitly ask about all NSAID use, including over-the-counter ibuprofen, naproxen, and aspirin, as patients frequently fail to report these medications 2, 3
Poor dietary iron intake occurs particularly in men of lower socioeconomic status with limited access to iron-rich foods 2
Vegetarian diets are inherently low in heme iron (the most bioavailable form), though this can be partially compensated by consuming iron with vitamin C 5

Urinalysis or urine microscopy should be performed in all cases to exclude urinary tract bleeding 1, 2
Regular blood donation depletes iron stores over time and represents a common overlooked cause 2
Chronic kidney disease impairs erythropoietin production and iron utilization 2
Chronic inflammatory conditions can cause functional iron deficiency where ferritin appears normal despite depleted stores 4
Androgen deprivation therapy in prostate cancer survivors suppresses erythropoiesis 2

Serum ferritin <15 μg/L is highly specific for iron deficiency (specificity 0.99) 4
Ferritin <45 μg/L warrants consideration of GI investigation, especially with chronic inflammation 4
A hemoglobin rise ≥10 g/L within 2 weeks of iron therapy strongly suggests absolute iron deficiency even with equivocal iron studies 1, 3
Celiac disease screening with tissue transglutaminase antibody should be performed as part of the initial workup 2, 3
Urinalysis or urine microscopy should be performed as part of the initial workup 1, 2
Comprehensive medication history focusing on NSAIDs and anticoagulants should be performed as part of the initial workup 2, 3
Upper endoscopy with duodenal biopsies should be performed as part of the initial workup 1, 3
Colonoscopy (preferred over CT colonography) should be performed as part of the initial workup 1, 3

Assuming dietary deficiency is the sole cause even with a positive dietary history—full GI investigation is still required in adult males 2
Failing to screen for celiac disease results in missed diagnoses in 3-5% of cases 2, 3
Not asking specifically about over-the-counter NSAID use leads to missed diagnoses 2
Accepting minor endoscopic findings (such as small hiatal hernia) as the sole explanation without completing lower GI investigation 3
Stopping investigation after finding one cause without considering dual pathology 2, 3

In adult men, approximately 95% of iron required for red blood cell production is recycled from breakdown of old red blood cells, with only 5% from dietary sources 5
Men normally lose approximately 1 mg of iron daily through feces and desquamated cells 5
Men store approximately 1.0-1.4 g of body iron, significantly more than women (0.2-0.4 g), making iron deficiency in men particularly concerning for pathological blood loss 5