Endocrine Abstracts

Background: Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is characterized by hyponatremia and hypoosmolality due to excessive ADH release. It is an uncommon initial presentation of adrenal insufficiency, particularly after abrupt cessation of potent topical corticosteroids. This case report describes a patient with severe atopic dermatitis (AD) who developed SIADH as a first sign of adrenal insufficiency after stopping clobetasol propionate, subsequently managed with dupilumab.

Case Presentation: A 40-year-old female with a longstanding history of severe atopic dermatitis unresponsive to conventional treatments presented with new-onset confusion, nausea, and generalized weakness. The patient had been applying clobetasol propionate 0.05% cream extensively for over three years and had recently discontinued it abruptly upon starting dupilumab therapy. On physical examination, the patient appeared disoriented and lethargic. Vital signs showed hypotension (BP 88/54 mmHg) and bradycardia (HR 60 bpm). Laboratory tests revealed severe hyponatremia (serum sodium: 118 mmol/l), low serum osmolality (250 mOsm/kg), and inappropriately high urine osmolality (550 mOsm/kg), consistent with SIADH. Further endocrine evaluation showed a significantly low serum cortisol level (240 mol/l) and subsequent Short Synacthen Test showed a blunted response with stimulated cortisol of 310 nmol/l and low ACTH (5.8 ng/l) confirming secondary adrenal insufficiency. Immediate management included 1.8% hypertonic saline for hyponatremia and fluid restriction. Clobetasol was reintroduced at a lower dose and tapered gradually, along with oral hydrocortisone. Dupilumab was continued, resulting in significant AD symptom improvement.

Discussion: This case underscores the need to recognise SIADH as a potential presentation of adrenal insufficiency following abrupt discontinuation of potent topical corticosteroids. Healthcare providers should be aware of the risks associated with HPA axis suppression in patients undergoing long-term potent topical corticosteroid therapy and ensure gradual tapering of these medications. Dupilumab is effective for severe AD but requires careful management of prior corticosteroid use.