Endocrine Abstracts

JOINT3891

Introduction: Periodic Paralysis (PP) is a rare neuromuscular disorder characterized by painless episodes of muscle weakness. This disorder can manifest as either hereditary or acquired, with the former typically being autosomal dominant and the latter frequently associated with hyperthyroidism. Thyrotoxic Periodic Paralysis (TPP) represents a specific subtype of hypokalemic periodic paralysis, marked by sudden onset weakness in proximal muscles, most commonly affecting the lower extremities. TPP is reversible through prompt potassium replacement and normalization of thyroid hormones. However, without timely detection and management, TPP can progress to involve all limbs and respiratory muscles. This form of periodic paralysis is frequently observed in males of Asian origin between the ages of 20 and 40.

Case: A 31-year-old male with no significant medical history presented with sudden and severe lower extremity weakness. Physical examination revealed a thin anxious individual with bilateral flaccid paralysis of the lower extremities with a power of 1/5. Vital signs were remarkable for high blood pressure of 152/77 mmHg. Investigations were remarkable for potassium level of 2.1 meq/l, and creatine kinase (CK) of 1,842 U/l. MRI of Spine was unremarkable. Potassium repletion was initiated both intravenously and orally. After three hours of starting the potassium repletion, the patient regained normal strength in the lower extremities. Further investigations revealed very low thyroid-stimulating hormone (TSH) of <0.008 mIU/l with elevated T3 529 ng/dl and T4 5 ng/dl, thyroid peroxidase antibody >900 IU/ml, and thyroid-stimulating immunoglobulin (TSI) of 436 % confirming our diagnosis of TPP.

Discussion: Thyrotoxic periodic paralysis (TPP) is triggered by factors such as exercise or carbohydrate intake, leading to a shift of potassium into cells and resulting in low blood potassium levels. While our patient falls within the most commonly affected sex and age group, his African American racial background makes this case less typical, as TPP is less frequently observed in this population. This case highlights the importance of considering hypokalemic periodic paralysis (HPP) as a differential diagnosis in any patient presenting with hypokalemia and sudden-onset paralysis. Treatment involves potassium replacement, correction of thyroid hormone levels, and a strong emphasis on patient education to prevent triggering factors.