Thyrotoxic periodic paralysis is an uncommon endocrine emergency marked by sudden muscle weakness linked to hypokalemia in the context of thyrotoxicosis. Cases have increasingly been reported worldwide, even though they are more common in Asian populations. Early detection is crucial because of the risk of life-threatening complications such as arrhythmias and respiratory failure. We present the case of a 42-year-old man with no significant medical history who exhibited sudden palpitations, diaphoresis, and anxiety, subsequently developing rapidly progressive lower extremity weakness, culminating in flaccid quadriparesis and acute respiratory failure requiring endotracheal intubation. Neurological examination indicated generalized weakness (0/5 strength) and areflexia, with no sensory deficit or cranial nerve involvement. Laboratory tests showed severe hypokalemia (1.3 mEq/L) and biochemical thyrotoxicosis, with low thyroid-stimulating hormone (TSH) levels (0.01 μIU/mL) and high free thyroxine (T4) levels (3.07 ng/dL). Neuroimaging and cerebrospinal fluid analysis yielded normal results. After carefully replacing potassium, the patient showed rapid clinical improvement with complete neurological recovery. Respiratory failure requiring mechanical ventilation is an uncommon presentation of thyrotoxic periodic paralysis and highlights the importance of early recognition. Thyrotoxic periodic paralysis must be contemplated in patients exhibiting acute flaccid paralysis and significant hypokalemia. Prompt diagnosis and treatment are crucial to prevent potentially fatal complications, such as respiratory failure or cardiac arrhythmias, which can arise from untreated thyrotoxic periodic paralysis.
Balderrama et al. (2026) studied this question.