A 10-year analysis of thyrotoxic periodic paralysis in 135 patients: focus on symptomatology and precipitants.
BACKGROUND
A comprehensive analysis has not been performed on patients with thyrotoxic periodic paralysis (TPP) characterized by acute hypokalemia and paralysis in the setting of thyrotoxicosis.


OBJECTIVE
The aim of this study was to analyze the detailed symptomatology of thyrotoxicosis and precipitating factors for the attack in a large cohort of TPP patients.


METHODS
A prospective observational study enrolled patients with TPP consecutively over 10 years at an academic medical center. Clinical features, including signs/symptoms of thyrotoxicosis and precipitating factors, were analyzed. The Wayne's index was used to assess the severity of thyrotoxicosis at presentation. Patients who agreed to receive an oral glucose-loading test after recovery were evaluated.


RESULTS
Among the 135 TPP patients (male:female, 130:5), 70% of paralytic attacks occurred in the morning, especially during the seasons of summer and fall. Two-thirds of patients did not have a known family or personal history of hyperthyroidism. Only 17% of TPP patients manifested overt signs/symptoms of thyrotoxicosis (Wayne's index >19). A clear precipitating factor, such as high carbohydrate load, acute upper respiratory tract infection, strenuous exercise, high-salt diet, or the use of steroids or bronchodilators, was identified in only 34% of TPP patients. A glucose load to stimulate insulin secretion induced acute hypokalemia (K(+)2.47±0.6 mmol/l) with reparalysis in only 18% (10/55) of TPP patients.


CONCLUSIONS
Most TPP patients have only subtle clinical signs/symptoms of thyrotoxicosis and only a small fraction has clear precipitating factors. In addition to the effects of hyperinsulinemia, other insulin-independent mechanisms may participate in the pathogenesis of TPP.
Division of Nephrology, Department of Medicine.
Chin-Chun
CC
Chang
Chih-Jen
CJ
Cheng
Chih-Chien
CC
Sung
Tzong-Shi
TS
Chiueh
Chien-Hsing
CH
Lee
Tom
T
Chau
Shih-Hua
SH
Lin
D000293:Adolescent; D000328:Adult; D005260:Female; D005947:Glucose; D006801:Humans; D006946:Hyperinsulinism / Q000209:etiology; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D010243:Paralysis / Q000139:chemically induced / Q000209:etiology* / Q000503:physiopathology; D011446:Prospective Studies; D012737:Sex Factors; D013960:Thyroid Function Tests; D013963:Thyroid Hormones / Q000097:blood; D013971:Thyrotoxicosis / Q000150:complications* / Q000503:physiopathology; D055815:Young Adult
D007328:Insulin; D013963:Thyroid Hormones; D005947:Glucose