Clinical Aspects in Patients with Thyrotoxic Periodic Hypokalemic Paralysis

Nam, Sang Yob; Kim, Jae Hong; Oh, Jung Hyn; Park, Jin Chul; Yoon, Hyun Dae; Won, Kyu Chang; Cho, Ihn Ho; Lee, Hyoung Woo; Sung, Cha Kyung

Abstract

BACKGROUND: Thyrotoxic periodic paralysis is an uncommon illness characterized by intermittent flaccid paralysis of skeletal muscle, usually accompanied by hypokalemia, in patient with hyperthyroidism. However. the pathophysiology of thyrotoxic periodic paralysis remains largely unexplained and controversial. This report describes the clnical and biochemical findings in 19 patients with thyrotoxic periodic paralysis who were examined at the Yeungnam University Medical Center (YUMC) during the past decade.
METHODS
The medical records of 997 YUMC patients, seen between 1986 and 1996, with dignosis of hyperthyroidism were reviewed. Nineteen patients out of 997 hyperthyrodism patients were diagnosed, and examined by history, physical examination, serum electrolyte value, and thyroid function test during paralysis. On the basis of these results, compasons were made on age. sex, precipitating factors, timing, affected limbs, prognosis, serum potassium and serum phosphate and thyroid hormone levels.
RESULTS
the prevalence of periodic paralysis in hyperthyroidism was 1.9 percent and the male to female prevalence ratio was 30:1 and in all patients, the development of perodic paralysis was correlated with hyperfuntional state of the throid gland. Eleven cases of periodic paralysis were associated with hypokalemia and their throid hormon levels were significantly more increased than those of the patients without hypokalemia. interestingly, our study shows the recurrence of paralysis after treatment.
CONCLUSION
Although the precise pathophysiology of the disease is as yet undefined and controversial, it occurs primarily in Asians with an overwhelming male preponderance and prevalence of 2 percent in hyperthyrodism. The interactive roles of thyroid hormon. Na-K pump. and genetically inherited defect in the celluar membrance potential of the skeletal muscle can be speculated. Further investigation will be neede to firmly establish the mechanism of thyrotoxic periodic paraysis.