Acrodermatitis enteropathica (AE) is the most common form of inherited zinc deficiency in humans.
Zinc is an essential trace element, crucial for immune defence, wound healing, growth, reproduction, and over 100 enzymatic processes.
ℹ️ About
- Zinc is a cofactor for >100 enzymes, including those for DNA/RNA synthesis and tissue repair.
- Total body zinc in an adult ≈ 2–3 g (mainly in muscle, bone, skin, liver).
- Zinc is absorbed in the jejunum; deficiency rapidly affects high-turnover tissues (skin, GI, immune cells).
⚙️ Aetiology
- Inherited: Acrodermatitis enteropathica (AR, SLC39A4 mutation → defective intestinal zinc transporter ZIP4).
- Nutritional: Poor intake, vegan/vegetarian diet without supplementation.
- Malabsorption: Bowel resection, IBD, coeliac disease, chronic diarrhoea.
- Increased losses: Diuretics, nephrotic syndrome, chronic liver disease, alcoholism.
- Increased demand: Pregnancy, lactation, rapid growth.
- Comorbidities: Diabetes mellitus, sickle cell disease, chronic kidney disease.
🧑⚕️ Clinical Features
- Skin: red, crusted periorificial dermatitis (mouth, nose, eyes, anus, genitalia); acral lesions (hands/feet).
- Hair: alopecia (diffuse or patchy).
- Growth/reproduction: short stature, delayed puberty, hypogonadism, fetal malformations, low birth weight.
- GI: diarrhoea, poor appetite, failure to thrive in children.
- Neuro/behavioural: irritability, depression, cognitive impairment.
- Other: hepatosplenomegaly, impaired wound healing, geophagia/pica.
🔬 Investigations
- Zinc levels: often low, but unreliable (affected by albumin, inflammation).
- Plasma albumin: low in malnutrition → affects zinc binding.
- Bloods (FBC, U&E, LFTs): to evaluate systemic disease and comorbidities.
- Diagnosis is clinical + confirmed by response to zinc supplementation.
💊 Management
- Therapeutic trial of zinc is diagnostic: dramatic resolution within days.
- Zinc supplementation: 15–120 mg/day orally (zinc sulphate or gluconate). Dose adjusted to age/weight.
- Lifelong treatment required in genetic AE.
- Monitor growth, puberty, fertility, wound healing, and recurrent infections.
- Diet: encourage zinc-rich foods (meat, shellfish, nuts, legumes).
📌 OSCE / Exam Tips
- Classic triad in AE: periorificial dermatitis + alopecia + diarrhoea.
- Inherited AE: presents after weaning (breast milk is protective due to high zinc bioavailability).
- Always consider zinc deficiency in: failure to thrive + dermatitis + alopecia.
- Response to zinc supplementation = both diagnostic and therapeutic.
📚 References