Reversible Bradycardia and Transient Loss of Consciousness With Undiagnosed Hypothyroidism: A Case Report

Hypothyroidism, or an underactive thyroid, is a common endocrine disorder characterized by insufficient production of thyroid hormones by the thyroid gland. It typically presents with non-specific symptoms and sometimes leads to serious cardiac and neurological symptoms. Due to the subtle onset, clinical recognition can be delayed. We present a case of a 62-year-old lady diagnosed with hypothyroidism presenting with bradyarrhythmia precipitating a syncopal attack. Extensive investigations were carried out to rule out a primary neurological or cardiac disorder, leading to diagnostic delays. A diagnosis of hypothyroidism is primarily established through blood tests showing an elevated thyroid-stimulating hormone (TSH) and low free thyroxine (T4) levels. Management involves long-term thyroid hormone replacement therapy, most commonly with levothyroxine, which effectively restores euthyroid status and alleviates symptoms in the majority of patients. Treating hypothyroidism in this patient led to complete symptom resolution, highlighting the importance of broadening our diagnostic approach in cases presenting with unexplained cardiovascular and neurological symptoms and emphasizes the importance of early detection and appropriate management to prevent complications.