Critical Cases: Acute generalized weakness



HPI: 35 yo hispanic M with history of gout and HTN, presents with acute onset generalized weakness, particularly pronounced in b/l upper and lower extremities. 

  • Symptoms started abruptly last night after a strenuous and stressful work day
  • No change in mental status
  • No recent illness, insect bites or rashes
  • Denies tremor, weight change, anxiety


Physical Exam:

  • Vitals WNL
  • Weakness most pronounced in proximal muscles, with legs slightly weaker than arms Grip strength preserved
  • Normal reflexes



  • Thyrotoxic periodic paralysis
  • Hypokalemic periodic paralysis
  • Myasthenic crisis
  • Guillain-Barre syndrome
  • Transverse myelitis
  • Tick paralysis


Initial Orders:

  • CBC, BMP, Thyroid panel (TSH, Free T3, Free T4), CK, Mag, Phos
  • EKG


Results and clinical course:

  • K: 1.7
  • Mag: 1.5
  • TSH < 0.01
  • Free T4: 5.9
  • T3, Free: 23.5
  • EKG: NSR with sinus arrhythmia and prolonged QTc



  • Replete with PO and IV potassium and IV magnesium
  • Symptoms began to improve rapidly with potassium replacement
  • Admit to telemetry monitored bed for at least 24h and check serial BMPs to monitor for rebound hyperkalemia
  • Patient started on methimazole for hyperthyroid


Teaching points:

  • Thyrotoxic periodic paralysis is a form of acquired hypokalemic periodic paralysis, often precipitated by rest after strenuous exercise or high carb load
  • Treat with KCl, continuous cardiac monitoring and monitor K levels for rebound hyperkalemia
  • For acute weakness not responsive to potassium replacement, use Propranolol
  • Treat hyperthyroidism - attacks should cease with euthyroid state




Chaudhry MA, Wayangankar S. Thryotoxic Periodic Paralysis: A concise review of the literature. Curr Rheumatol Rev. 2016;12(3):190-194.

Kung AW. Clinical review: Thyrotoxic periodic paralysis: a diagnostic challenge. J Clin Endocrinol Metab. 2006 Jul;91(7):2490-5. Epub 2006 Apr 11.

Vijayaumar A, Ashwath G, Thimmappa D. Thyrotoxic periodic paralysis: clinical challenges. J Thyroid Res 2014;2014:649502