Abstract Case Report A 51-year-old female with Hashimoto’s thyroiditis status post-thyroidectomy was admitted for worsening respiratory distress despite outpatient management. She had been discharged on 4 L home oxygen and a steroid taper one week earlier after a similar episode. On admission, her oxygen was increased to 6 L, and examination showed diminished bilateral breath sounds with nonlabored respirations. She was initially treated with bronchodilators and steroids, but her dyspnea worsened with intermittent desaturations to the 70s.Echocardiogram revealed preserved ejection fraction with indeterminate diastolic function. Chest imaging ruled out infection, while bacterial and viral PCRs, procalcitonin, ANA, ANCA, and MPO were unremarkable. Laboratory testing showed severe hypothyroidism (TSH 215 mU/L, free T4 0.07 ng/dL).Due to concerns for respiratory failure, pulmonary function testing revealed reduced respiratory muscle strength (vital capacity 2 L, MIP -38 cmH2O, NIF -25 cmH2O, MEP 38 cmH2O), consistent with neuromuscular weakness. Spirometry demonstrated a restrictive pattern (FVC 23% predicted, FEV1 22%, preserved ratio 0.80). BAL was negative. EMG showed demyelinating neuropathy of the upper extremities, and CSF analysis revealed pleocytosis and elevated protein, suggesting an inflammatory process. She was treated with levothyroxine 75 mcg daily, a 5-day IVIG course (200 ml/hr × 24 h), and noninvasive positive pressure ventilation (NIPPV) with symptomatic improvement. She was discharged on home NIPPV without a steroid taper. Two weeks later, pulmonary function improved markedly (FVC 23%→62%, FEV1 22%→66%, FEV1/FVC 0.80→1.05). Discussion This case demonstrates a rare association between Hashimoto thyroiditis-related hypothyroidism and CIDP presenting with respiratory failure. Demyelinating neuropathy in Hashimoto’s thyroiditis is exceedingly uncommon (1), reflecting immune dysregulation and antibody cross-reactivity with peripheral nerve antigens (2). The patient’s profound hypothyroidism likely precipitated or worsened autoimmune demyelination through molecular mimicry. The respiratory failure component, marked by low vital capacity and inspiratory force, represents an atypical, life-threatening CIDP manifestation. Prompt diagnosis and treatment are crucial. The patient’s rapid improvement with thyroid hormone replacement and IVIG highlights the need to address both endocrine and autoimmune factors. This case underscores the importance of medication adherence in autoimmune thyroid disease and the potential for severe neurological complications when hypothyroidism is uncontrolled. Both CIDP and Hashimoto thyroiditis share autoimmune mechanisms that may cause cross-reactive immune responses targeting thyroid and peripheral nerve antigens (4). This abstract is funded by: NONE
Edwards et al. (Fri,) studied this question.