An 8-month-old infant recently weaned from exclusive breastfeeding presents with chronic watery diarrhea, symmetrical vesiculobullous and eczematous lesions around the mouth, anus, and on the acral surfaces, along with diffuse alopecia. Which single investigation will best confirm the underlying defect?
- A Serum zinc level ✓
- B Skin biopsy showing necrolytic migratory erythema
- C Serum alkaline phosphatase
- D Urine organic acid profile
Correct answer: A. Serum zinc level
Explanation
The classic triad of periorificial and acral dermatitis, chronic diarrhea, and alopecia in an infant around weaning defines acrodermatitis enteropathica, caused by defective intestinal zinc absorption (ZIP4 transporter mutation). A low serum zinc confirms the diagnosis, and dramatic clinical response to oral zinc supplementation is both diagnostic and curative. Alkaline phosphatase falls in zinc deficiency but is nonspecific.
Reference: Ghai Essential Pediatrics, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.