Health Education

Manifestations of Hypokalemic Paralysis

Thyrotoxic periodic paralysis (TPP) occurs occasionally in patients with hyperthyroidism, with the manifestations being mainly hypokalemia and sudden muscle weakness. According to the literature records and case review, it was more likely to occur in Asians, with the incidence of hyperthyroidism in Asian patients about 2%, while that in North America was about 0.1% ~ 0.2%, and most aged 20 ~ 40 years old.

Generally speaking, hyperthyroidism is more likely to occur in women, but curiously, TPP is more likely to occur in men, and the incidence ratio of male to female varies from 17:1 to 70:1 according to studies.

Symptoms

Symptoms of TPP include systemic or localized muscle weakness. Muscle weakness is more severe in the proximal muscles (e.g., upper arms, thighs) than in the distal muscles and usually affects the lower extremities more than the upper extremities. The onset time of muscle weakness may vary from several hours to several days. During the attack, a number of deep tendon reflex decreases or disappears, and the onset may be repeated over several days.

TPP usually occurs only when the thyroid function is abnormal. If the patient's thyroid function can be stably controlled within a normal range, it is not easy to develop the disease. It should also be noted that if the patient has been suffering from hyperthyroidism, the disease can easily be induced by high-sugar diet, alcohol consumption and intense exercise.

In the analysis of hyperthyroidism among patients with TPP, Graves' disease still ranks first.

Etiology

Hypokalemia in hyperthyroidism-associated periodic myasthenia is due to temporary potassium migration into the cell. Elevated thyroxine increases the activity of the sodium-potassium pump (Na+/K+ -ATPase) and raises the chance of potassium transferring to muscle cells and bulbar cells. Hypokalemia may be caused by the transfer of potassium into cells, so in fact, potassium is not lost by the kidney through urine in large quantities, and the actual total content of potassium ions in the body is not deficient. TTKG is less than 3 at the onset and the urine K+/Creatinine ratio is less than 2 meq/mmol.

The main pathogenic causes of TPP are hyperthyroidism and hypokalemia. Therefore, formal antithyroid drugs (e.g. methimazole or propylthiouracil) and propranolol should be given for the treatment to restore the thyroid function to normal. Of course, surgery or radioactive iodine-131 can be used for treatment, and appropriate potassium supplementation can improve the symptoms of limb paralysis and reduce the occurrence of arrhythmia.