In Thyrotoxicosis there is

(B) Hypokalemic Periodic Paralysis> Acute generalized weakness due to thyrotoxic periodic paralysis# Thyrotoxic periodic paralysis (TPP) is a disorder characterized by thyrotoxicosis, hypokalemia and predominantly proximal lower limb paralysis. Despite the female predominance of hyperthyroidism, TPP occurs most frequently in males in a ratio of 20:1, and 90% of patients are of Asian descent> Prodromal symptoms may consist of muscle stiffness or cramping. Sensation, as well as bulbar and respiratory muscle strength, remains intact.> Reflexes may be decreased or absent.> Attacks may be precipitated by a high carbohydrate meal (secondary to insulin secretion) or physical exertion.> In one series, 84% of attacks occurred between 1 and 6 am. Episodes are acute in onset and last 1-96 hours. As in this patient, symptoms and signs of hyperthyroidism may be subtle at initial presentation.> Electrocardiographic findings such as ST-segment depression with T-wave flattening and the presence of U waves are typical of hypokalemia. Findings supportive of a diagnosis of TPP are sinus tachycardia, elevated QRS voltage and first-degree AV block.> Pump sensitivity to adrenergic stimulation may be higher in patients with TPP than in those with hyperthyroidism alone, resulting in intracellular potassium shift and subsequent hypokalemia.