Complete heart block during potassium therapy in thyrotoxic periodic paralysis.
BACKGROUND
Although cardiac dysrhythmia is common in patients with thyrotoxic periodic paralysis (TPP), high-degree atrioventricular (AV) block complicated by cardiogenic shock, even under KCl supplementation, is rarely described.


OBJECTIVE
To present a case of TPP in a patient who developed complete AV block with severe consequences due to paradoxical hypokalemia during KCl therapy. In addition, the management of acute hypokalemia in TPP is reviewed.


METHODS
A 41-year-old Chinese man with TPP presented to the Emergency Department with a 2-day history of paralysis in the extremities. He developed complete AV block with cardiogenic shock and respiratory failure, necessitating ventilatory support when plasma K(+) level decreased from 1.7 mmol/L to 1.3 mmol/L during KCl replacement of 30 mmol in 2 h. The administration of another 60 mmol KCl over 3 h achieved a plasma K(+) level of 2.1 mmol/L, resulting in the resolution of AV block and successful weaning. However, rebound hyperkalemia (K(+) 5.6 mmol/L) upon recovery was evident and uneventfully corrected.


CONCLUSIONS
A paradoxical fall in serum K(+) concentration with potentially life-threatening complication is still underappreciated in patients with TPP on KCl supplementation. Early recognition and prompt therapy prevent untoward consequences.
Division of Endocrinology and Metabolism, Department of Internal Medicine, Saint Mary's Hospital, Luodong, Yilan, Taiwan.
Huei-Fang
HF
Wang
Shih-Ching
SC
Tsai
Ming-Sung
MS
Pan
Chih-Chung
CC
Shiao
D000328:Adult; D004562:Electrocardiography; D006327:Heart Block / Q000209:etiology*; D006801:Humans; D020514:Hypokalemic Periodic Paralysis / Q000150:complications / Q000188:drug therapy*; D008297:Male; D011189:Potassium Chloride / Q000627:therapeutic use*
D011189:Potassium Chloride