Hypokalemic Paralysis Revealing Subclinical Hyperthyroidism: A Case report of Thyrotoxic Periodic Paralysis

Hypokalaemic Periodic Paralysis in a Patient with Subclinical Hyperthyroidism

Abstract

Introduction: Thyrotoxic periodic paralysis is a rare, potentially life-threatening hyperthyroid complication causing transient muscle weakness due to intracellular potassium shift and hypokalemia.

Case Presentation: A 41-year-old man presented with a sudden onset of symmetrical weakness in all limbs. Laboratory evaluation revealed significant hypokalemia (serum potassium 2.3 mmol/L) and suppressed TSH, with low normal thyroid hormone levels, consistent with thyrotoxicosis. The patient also exhibited clinical signs of hyperthyroidism, including heat intolerance, tremors, diaphoresis, and sinus tachycardia.

Management: Intravenous potassium replacement led to rapid resolution of symptoms. He was subsequently treated with propranolol and carbimazole. At four-week follow-up, the patient remained asymptomatic with normalization of both serum potassium and thyroid function.

Conclusion: This case highlights the importance of considering TPP in patients with hypokalemic paralysis, even in the absence of classic hyperthyroid features or common triggers. Early diagnosis and appropriate treatment can reverse paralysis and prevent serious complications like cardiac arrhythmias.