Iron Deficiency Due to Gastrointestinal Blood Loss

Iron deficiency due to gastrointestinal blood loss occurs when chronic loss exceeds iron absorption (about 1 to 2 mg daily), exhausting body iron stores.

• One millilitre of blood contains about 0.5 mg of iron; losses of 5 to 10 mL daily produce deficiency in months.
• Causes: peptic ulcer and erosive gastritis, NSAIDs, colorectal cancer and polyps, angioectasia, hookworm and other helminths (a major cause in Kenya), gastric cancer, oesophagitis, coeliac disease and inflammatory bowel disease (blood loss plus malabsorption), schistosomiasis.
• Risk groups: children in endemic areas, adolescents, pregnancy, older adults.

Fatigue, headache, dizziness, exertional dyspnoea, restless legs, hair loss, pica, impaired cognition.

• Pallor, koilonychia, glossitis, angular cheilitis, tachycardia, flow murmur.
• Symptoms of the source: dyspepsia, change in bowel habit, abdominal pain, melaena.
• Differential diagnosis: thalassaemia trait, anaemia of chronic disease, sideroblastic anaemia, lead poisoning, other iron-losing states (menorrhagia, urinary blood loss), dietary deficiency, malabsorption.
• Complications: heart failure, poor pregnancy outcomes, developmental delay in children, reduced work capacity, thrombocytosis.

Haemoglobin below 13 g/dL in men and below 12 g/dL in women, microcytosis (MCV below 80 fL), hypochromia, pencil cells on film.

• Ferritin below 30 microgram/L diagnoses iron deficiency (below 100 microgram/L with inflammation); transferrin saturation below 20 percent; raised total iron binding capacity and soluble transferrin receptor.
• Source search: faecal occult blood, stool for ova and parasites, tissue transglutaminase antibody with total IgA, upper endoscopy with duodenal biopsy and colonoscopy for adult men and postmenopausal women, and for premenopausal women with gastrointestinal symptoms or family history.
• Urine microscopy for schistosome ova where relevant.

Supportive: treat the cause, dietary iron advice, avoid tea with iron tablets.

Pharmacological

• Oral ferrous sulfate 200 mg (65 mg elemental) once daily or on alternate days, with vitamin C 250 mg to enhance absorption; continue 3 months after haemoglobin normalises. Children 3 to 6 mg/kg/day elemental iron in divided doses.
• Intravenous iron for intolerance, malabsorption, ongoing blood loss, inflammatory bowel disease or chronic kidney disease: ferric carboxymaltose 1000 mg single dose (maximum 20 mg/kg) repeated after 1 week if needed, or iron sucrose 200 mg on 5 occasions over 14 days.
• Hookworm: albendazole 400 mg single dose (children over 1 year; 200 mg for ages 12 to 23 months); schistosomiasis: praziquantel 40 mg/kg single dose.
• Transfusion only for haemoglobin below 7 g/dL or haemodynamic compromise.

Procedures: endoscopic or surgical treatment of the bleeding lesion.

Special groups: pregnancy (oral iron 60 mg elemental daily; intravenous iron in the second and third trimesters if severe), children (deworming every 6 months in endemic areas), heart failure patients (intravenous iron improves functional capacity).

Red flags: age above 50 years, weight loss, melaena, family history of colorectal cancer, failure to respond to iron.

Follow-up: haemoglobin rise of 2 g/dL within 4 weeks; ferritin at 3 months; repeat investigation if not responding after correcting adherence.