SAT-207 - Primary Adrenal Insufficiency Presenting as A Restrictive Eating Disorder in an Adolescent

Addison disease is a potentially devastating condition, most commonly presenting in adults between 30 and 50 years of age, and is rare in the pediatric population. This rarity, combined with nonspecific symptoms and an insidious onset, frequently contributes to delayed diagnosis. We report a case in which a pre-existing diagnosis of restrictive eating disorder (RED) masked an underlying diagnosis of Addison disease.

A 16-year-old female with a prior diagnosis of RED presented to our emergency department complaining of dizziness that had worsened in the last weeks. She reported years of intermittent dizziness and recurrent hyponatremia on screening laboratory evaluations, consistently attributed to her underlying RED, diagnosed at the age of 14. She had also experienced considerable weight loss, from 90kg to 49.25 kg, with a BMI of 19.65 kg/m² (-0.37 SD). On arrival, she was noted to have orthostatic tachycardia, and a sodium of 129 mmol/L. Cardiology workup showed a normal echocardiogram, ultimately shifting the diagnosis toward postural orthostatic tachycardia syndrome. She started salt and fluid repletion, with only mild improvement of symptoms and persistent hyponatremia and hypochloremia. Her clinical course subsequently worsened with the development of severe hyperkalemia (up to 7.3 mmol/L), worsening hyponatremia, and hypotension. These findings prompted evaluation for adrenal insufficiency, confirmed by low morning cortisol levels and an abnormal ACTH stimulation test. Following confirmation of adrenal insufficiency, a more detailed history revealed progressive darkening of her skin over several years, particularly on palmar creases and friction areas. She started hydrocortisone and fludrocortisone, stabilizing potassium levels to 5.0 mmol/L and correcting hyponatremia in a matter of hours. There was also an improvement in dizziness and the general wellbeing of the patient. In the following days, weight became up trending, and she was discharged home.

Patients with Addison may remain undiagnosed for years, particularly when disease coexists with restrictive eating disorders (RED), as in our case. Overlapping features such as weight loss, malnutrition, fatigue, dizziness, and hypotension may be attributed solely to RED, delaying recognition of adrenal insufficiency. These diagnostic challenges highlight the importance of maintaining a broad differential diagnosis for hyponatremia and orthostatic symptoms in adolescents, even in the presence of a prior RED diagnosis. Addison disease is treatable, and early recognition and treatment are essential to prevent morbidity and mortality and to improve quality of life. Notably, even if hyperkalemia is absent, isolated hyponatremia should raise suspicion for this condition. Finally, clinicians should be aware of cognitive biases, particularly anchoring bias, which can delay recognition of concurrent conditions.

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