Episodes of paralysis in Chinese men with thyrotoxic periodic paralysis are associated with elevated serum testosterone

A single-center retrospective study on the clinical features of thyrotoxic periodic paralysis

PURPOSE

Thyrotoxic periodic paralysis (TPP) is characterized by muscle paralysis and significant intracellular potassium movement resulting in hypokalemia. Since TPP is a rare condition, only a few studies have explicated the clinical characteristics of patients with this disease. This study aimed to elucidate the clinical characteristics of patients with TPP by comparing them with those with thyrotoxicosis without paralysis (non-TPP) and sporadic periodic paralysis (SPP).

METHODS

This was a single-center retrospective cohort study. Clinical data of patients with hyperthyroidism (n = 62) or periodic paralysis (n = 92) who were emergently admitted to our hospital was extracted from the electronic medical records and analyzed.

RESULTS

All patients in the TPP group (15 males and 2 females) had Graves' disease, with 14 being newly diagnosed. The average serum potassium level on admission was 2.3±0.75 mEq/L. No significant correlation was observed among serum potassium level, amount of potassium required for normalization, and thyroid hormone levels. The TPP group showed significantly younger age, higher male ratio and body mass index (BMI), and lower serum potassium and phosphorus levels than the non-TPP group, which comprised 36 patients with Graves' disease. No significant differences were observed between the TPP and SPP (n = 11) groups in terms of age, sex, BMI, serum electrolyte levels, potassium requirement for normalization, and recovery time.

MAIN CONCLUSIONS

Considering that most patients with TPP have undiagnosed Graves' disease, distinguishing TPP from SPP based on clinical information and course alone is difficult in emergency settings. Therefore, for early detection and launch of specific treatment of Graves' disease, screening for thyroid hormone and anti-thyroid stimulating hormone receptor antibody levels is necessary when treating patients with periodic paralysis.

An Unusual Presentation of Thyrotoxicosis: Leg Weakness and Hypokalemia in a 21-Year-Old Male

Patients with hyperthyroidism or thyrotoxicosis present with an unspecific constellation of signs or symptoms such as palpitations, tremors, weight loss, or diarrhea. In some severe cases, hyperthyroidism can predispose patients to metabolic abnormalities and arrhythmias. Thyrotoxic periodic paralysis (TTP) is a rare, life-threatening complication or variant of hyperthyroidism associated with hypokalemia and muscle weakness that affects young Asian or Hispanic males between 20–40 years. TTP is reversible, and the management consists of beta-blockers, antithyroid therapy, and conservative potassium correction to prevent severe cardiovascular events such as ventricular arrhythmias with the improvement of transient muscle paralysis. We present a case of a 21-year-old Hispanic male complaining with symptoms of thyrotoxicosis, marked hypokalemia, and severe generalized muscle weakness. Physicians must be aware of this uncommon complication of thyrotoxicosis called thyrotoxic periodic paralysis (TTP) to avoid potassium overcorrection and all the endocrine associations with this pathology.

A Rare Case of Thyrotoxic Periodic Paralysis After Epidural Steroid Injection: A Case Report and Literature Review

Patient: Male, 36

Final Diagnosis: Epidural steroid induced thyrotoxic periodic paralysis

Symptoms: Paralysis

Medication: —

Clinical Procedure: Epidural steroid injection

Specialty: Endorinology and Metabolic

Does thyrotoxic periodic paralysis have a genetic predisposition? A case report

Thyrotoxic periodic paralysis is a rare complication of hyperthyroidism where increased influx of potassium into skeletal muscle cells leads to profound hypokalaemia and paralysis. Most cases arise sporadically in Asians; however, it is being increasingly reported in Caucasians. It is regarded as a channelopathy where a genetic and/or acquired defect in the sodium-potassium (Na/K-ATPase) pump renders it more sensitive to excess thyroid hormone in susceptible individuals. Because the clinical presentation is similar to familial hypokalaemic periodic paralysis, genes implicated in this autosomal-dominant condition became candidates for thyrotoxic periodic paralysis, particularly if they were known to have thyroid hormone-responsive elements. These include the voltage-gated calcium (CACNA1S) and sodium (SCN4A) channel genes, KCNJ18 which encodes the inwardly rectifying potassium channel Kir2.6, and subunits of the Na/K-ATPase genes. Although no single pathogenetic mutation has been identified in thyrotoxic periodic paralysis, several single-nucleotide polymorphisms in these genes have been associated with it. We describe a 27-year-old Caucasian Irish male who presented with acute onset limb paralysis and severe hypokalaemia. He was diagnosed as having thyrotoxic periodic paralysis secondary to Graves' disease based on clinical presentation, biochemical findings and rapid response to intravenous potassium. Genetic analysis identified heterozygous variants in three candidate genes: KCNJ18 (c.576G>C), SCN4A (c.2341G>A) and CACNA1S (c.1817G>A). Since these variants are not disease causing and occur at high prevalences of 50%, 2-3% and 1%, respectively, in the normal population, they do not explain the clinical phenotype in our patient suggesting that acquired environmental triggers or as-yet unidentified gene mutations remain as leading pathogenetic co-factors in thyrotoxic periodic paralysis.

Long Exercise Test in the Interattack Period of Periodic Paralysis: A Useful and Sensitive Diagnostic Tool

PURPOSE

The reference values of long exercise test are inconsistent in previous studies. Our research aims to determine the reference values and improve diagnostic efficiency of long exercise test in periodic paralysis.

METHODS

In this study, 100 healthy controls, 35 non-periodic paralysis patients, and 47 patients with periodic paralysis were recruited. The procedures of long exercise test were conducted following McMannis(1986) method.

RESULTS

The decrease rate in compound muscle action potential amplitudes was correlated with gender, and it was not influenced by age, height, weight, and exercise. After analyzing receiver operating characteristic curves, the compound muscle action potential amplitude decrease rate was stratified by sex. The mean area under the curve, sensitivity, and specificity were higher in male and female than all pooled subjects. The reference values of compound muscle action potential amplitude decrease rate were 46.8% in male and 26.9% in female, respectively.

CONCLUSIONS

The long exercise test is a useful and sensitive diagnostic tool for primary periodic paralysis and thyrotoxic periodic paralysis. However, the reference values should be set by sex, which has better diagnostic performance, sensitivity, and specificity.

Thyrotoxic periodic paralysis: a case study and review of the literature

Acute hypokalemic paralysis is a rare cause of acute weakness. Morbidity and mortality associated with unrecognized disease can occur and include respiratory failure and possibly death. Common causes of hypokalemic paralysis include thyrotoxic periodic paralysis (TPP) which is a disorder most frequently seen in Asian males. TPP is characterized by sudden onset of hypokalemia and paralysis that primarily affects the lower extremities. Treatment of TPP includes replacing potassium rapidly, using nonselective beta-blockade and correcting the underlying hyperthyroidism as soon as possible. TPP is curable once euthyroid state is achieved. It is vital for physicians to be able to differentiate TPP from familial hypokalemic periodic paralysis, a more common cause of periodic paralysis in Caucasians and western countries. We describe a 19-year-old Caucasian man who presented with acute onset lower extremity paralysis secondary to acute hypokalemia and was found to have new onset Graves’ disease.

Abbreviations: TPP: Thyrotoxic periodic paralysis

Thyrotoxic hypokalaemic periodic paralysis: a rare presentation of Graves' disease in a Hispanic patient

A 26-year-old Hispanic man with no significant medical history presented to our emergency room with gradual onset weakness of his lower extremities. He was haemodynamically stable and examination revealed loss of motor function in his lower limbs up to the level of hips. Laboratory data revealed hypokalaemia. The patient was started on potassium supplementation and he recovered his muscle strength. Differential diagnosis included familial hypokalaemic periodic paralysis and thyrotoxic periodic paralysis (TPP). Further investigations revealed a low thyroid-stimulating hormone and high free thyroxine levels. Radio iodine 123 scan revealed an enhanced homogeneous uptake in the thyroid suggesting Graves' disease. Thyroid stimulating antibodies were also found to be elevated. The patient was started on methimazole and propranolol and he never had another attack of TPP even at 1 year follow-up.

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.

PURPOSE

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.

PATIENTS AND 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.