Endocrine Abstracts

Introduction: Atopic dermatitis can cause significant exudative fluid loss from a large body surface area in an infant leading to severe hyponatraemia.

Case report: A 5-month-old boy was referred to the paediatric team from dermatology with severe cradle cap, eczema and fever. He also had faltering growth (weight: 4.95 kg, well below 0.4th centile) and moderate developmental delay. On examination, he had severe infected eczema over a large area of the scalp. Initial blood tests showed sodium: 120 mmol/l, potassium: 5.7 mmol/l and albumin: 21 g/l. Urinary sodium was <10 mmol/l ruling out renal sodium loss. He had markedly raised plasma aldosterone and renin levels at 36 100 pmol/l (reference range: 100–450) and 18 pmol/l (reference range: 1.1–2.7) respectively. However, serum ACTH, cortisol and thyroid function tests were normal. His total IgE was markedly elevated at 9800 u/ml and specific IgE to cow’s milk was highly positive (class 5). Other immunoglobulins were normal and coeliac screen was negative. His cradle cap improved gradually with oral antibiotics, topical steroid therapy, emollients and cow’s milk avoidance. Hyponatraemia was initially corrected with sodium chloride supplementation. His plasma sodium improved to normal range within 2 weeks and sodium supplements could be stopped within 4 weeks of initial presentation. Blood tests repeated 2 months later showed decreasing levels of serum aldosterone levels. At his clinic visit 4 months later, he showed normal biochemistry, good improvement in growth parameters and developmental milestones.

Conclusion: Severe infantile atopic dermatitis can result in significant electrolyte abnormalities such as hyponatraemia and hyperkalaemia leading to pseudohypoaldosteronism. This could affect developmental progress and growth parameters. Rigorous treatment with topical steroid therapy and emollient creams to prevent exudative fluid loss along with temporary sodium supplementation may be required to correct electrolyte imbalance. It is important to consider severe infantile eczema as one of differential diagnoses of pseudohypoaldosteronism.