Thyrotoxic Periodic Paralysis: Clinical Challenges

Abstract

Thyrotoxic periodic paralysis (TPP), a disorder most commonly seen in Asian men, is characterized by abrupt onset of hypokalemia and paralysis. The condition primarily affects the lower extremities and is secondary to thyrotoxicosis. The underlying hyperthyroidism is often subtle causing difficulty in early diagnosis. Factors like high-carbohydrate meal exercise, steroid, and stress can precipitate an attack of TPP. Evidence is building up showing role of genetic mutations in Kir2.6 channel in the pathogenesis of TPP. Loss of function of Kir2.6 together with increased activity of Na+/K+ ATPase may trigger a positive feed-forward cycle of hypokalemia. Biochemical hyperthyroidism with normal urinary potassium excretion and ECG changes are characteristic of TPP. Treatment with low-dose potassium supplements and nonselective beta-blockers should be initiated upon diagnosis, and the serum potassium level should be frequently monitored to prevent rebound hyperkalemia.

Thyrotoxic periodic paralysis- A case report

“…Depending on the general condition of the patient , potassium supplementation is given either orally or intravenously. 2 One prospective study compared treatment with intravenous potassium chloride to normal saline infusion and found a shorter recovery time with use of potassium (6.3 v/s. 13.5 hours Non-selective beta blockers like propranolol can be given at the time of acute attacks and also to prevent recurrence.…”

“…Acetazolamide, which has been reported to decrease the frequency of paralytic attacks in FHPP, should never be given to patients with TPP as it may actually worsen the attack. 2 Although glucocorticoids have been used to treat hyperthyroidism, they may also produce detrimental effects, including the development of TPP. A literature review revealed at least 2 cases of TPP induced by methylprednisolone and 2 cases caused by a single dose of prednisone.…”

“…1 Treatment with low-dose potassium supplements and nonselective beta-blockers should be initiated upon diagnosis, and the serum potassium level should be frequently monitored to prevent rebound hyperkalemia. 2 The incidence of TPP in Chinese and Japanese thyrotoxic patients has been reported at 1.8% and 1.9%, respectively, whereas in North Americans at 0.1%-0.2%. In the Chinese, TPP occurs in 13% of male and 0.17% of female thyrotoxic patients, in a series published in 1967.…”

“…1 The etiology of hypokalemic paralysis can be generally classified into two groups: hypokalemic periodic paralysis due to shift of potassium into the intracellular space without a total potassium deficit, and nonhypokalemic periodic paralysis due to a large potassium deficit via gastrointestinal or renal loss. 2 Thyrotoxic periodic paralysis (TPP) is a potentially lethal manifestation of hyperthyroidism, which is characterized by hypokalemia and muscular weakness due to intracellular shift of potassium and subsequent hypokalemia. 3 Although Graves' disease represents the most common cause, TPP can appear with hyperthyroidism of any origin: hyperfunctional multi-nodular goiter, TSH-secreting pituitary adenoma, subacute thyroiditis of de Quervain, JodBasedow disease, amiodarone therapy, an overdose of thyroid hormone, thyrotoxicosis factitia, and in one report, a single toxic adenoma.…”

“…In the Chinese, TPP occurs in 13% of male and 0.17% of female thyrotoxic patients, in a series published in 1967. The male to female ratio ranges from 17: 1 to 70: 1 despite the fact that hyperthyroidism is more common in females (female-to-Journal of International Medicine and Dentistry 2017;4(1): [1][2][3][4][5] male ratio of 9: 1). 2 We report the clinical and laboratory findings in a patient with TPP without associated symptoms of thyrotoxicosis.…”