PAS the Salt: A Case of Autoimmune Polyglandular Syndrome Type II

Abstract

CASE DESCRIPTION: Here we present the case of a 71 year old female with a decades-long history of Hashimoto thyroiditis and vitiligo who developed Addison Disease (AD). Routine labs showed serum sodium of 124, and the patient reported fatigue and lightheadedness on follow-up with her primary care physician. Despite discontinuation of hydrochlorothiazide, subsequent labs showed Na of 112 and she was sent to the emergency department and found to have hypoosmolar hyponatremia consistent with syndrome of inappropriate antidiuretic hormone secretion. Fluid restriction, saline infusion, and later sodium-chloride tablets failed to improve sodium levels two days after admission. Further investigation revealed low morning cortisol that did not respond to adrenocorticotropic hormone (ACTH) stimulation, demonstrating adrenal insufficiency. Later workup revealed elevated serum ACTH and positive 21-hydroxylase antibodies consistent with autoimmune adrenalitis. CONCLUSION: AD, albeit rare, is important to consider in severely hyponatremic patients with established monoglandular endocrinopathy. CLINICAL SIGNIFICANCE: The patient has autoimmune polyglandular syndrome type II (PAS-II), defined by the presence of AD and either autoimmune thyroid diseases (AITDs) and/or type one diabetes mellitus; patients may also exhibit other autoimmune conditions such as pernicious anemia, premature ovarian failure, alopecia, vitiligo, celiac disease, or multiple sclerosis. PAS-II is a rare diagnosis with a prevalence of 1-2 per 100,000 and a male-to-female ratio of 1:3. It is usually not recommended to routinely screen for other autoimmune diseases in patients with existing AITDs. Autoimmune endocrinopathies pose potential harms to patients, such as life-threatening adrenal crisis, metabolic derangements, infertility, and worsened quality of life; these harms ought to be considered in deciding if and how often to screen for concomitant autoimmune disorders in patients with monoglandular autoimmune endocrinopathies.