Thyrotoxic Periodic Paralysis is uncommon in
childhood, with approximately 80% of cases presenting after the age of 20
years. Symptoms include myalgia, fatigue, muscle weakness, and symptoms of
hyperthyroidism, although these are often subtle. There may be a history of
weakness related to exercise and carbohydrate or alcohol intake. Proximal
muscles are more affected than distal muscles, and lower limbs more than
upper limbs. Examination commonly reveals a goiter and flaccid paralysis in
the affected muscles. Respiratory and bulbar muscles are rarely involved.
Cardiac dysrhythmias (atrial fibrillation/ flutter, supraventricular
tachycardia ventricular extrasystoles) are common. Electrocardiographic
changes reflect the hypokalemia (U waves, small T wave, ST depression, long
QT interval). Definitive treatment is correction of the hyperthyroidism.
Beta2-antagonism with propranolol may prevent paralysis in the face of
hypokalemia. Potassium supplementation may be used in the setting of acute
paralysis; however, it should be noted that body potassium stores are normal
and that hyperkalemia may occur as paralysis resolves.