Thyrotoxic periodic paralysis with ventricular tachycardia

Management of hypokalemia in patients with thyrotoxicosis periodic paralysis in Soetomo general hospital: A case report

Introduction

The prevalence of Graves' disease varies widely between 21 and 80% of all cases of hyperthyroidism. Research conducted in 2018 at the Dr. Soetomo Regional General Hospital Surabaya found Graves' disease in as many as 66.7% of all cases of hyperthyroidism. Thyrotoxicosis Periodic Paralysis (TPP) is a disorder characterized by reversible muscle weakness and paralysis, accompanied by hypokalemia, which usually accompanies hyperthyroidism, mostly caused by Graves' disease. Management of severe hypokalemia in TPP is challenging.

Case illustration

male, 29 years patient complained that both lower legs felt weak in the last 6 hours before coming to the hospital emergency department. The patient was diagnosed with hyperthyroidism in 2018. A fine tremor was found, and the patient was admitted to the hospital for 4 days and routinely controlled at the endocrine polyclinic.

Clinical discussion

The underlying disease or causative etiology of thyrotoxicosis must be determined before treatment is conducted. The main concern when performing potassium replacement therapy is the occurrence of rebound hyperkalemia because this hypokalemia condition is caused not by total potassium depletion.

Conclusion

The principles of management for thyrotoxicosis periodic paralysis are proper diagnosis, exclusion of other causes of paralysis, and other causes of hypokalemia, slow and gradual correction of hypokalemia, and close and careful clinical monitoring, ECG, and laboratory.

Molecular stratification of arrhythmogenic mechanisms in the Andersen Tawil Syndrome

Andersen Tawil Syndrome (ATS) is a rare inheritable disease associated with loss-of-function mutations in KCNJ2, the gene coding the strong inward rectifier potassium channel Kir2.1, which forms an essential membrane protein controlling cardiac excitability. ATS is usually marked by a triad of periodic paralysis, life-threatening cardiac arrhythmias and dysmorphic features, but its expression is variable and not all patients with a phenotype linked to ATS have a known genetic alteration. The mechanisms underlying this arrhythmogenic syndrome are poorly understood. Knowing such mechanisms would be essential to distinguish ATS from other channelopathies with overlapping phenotypes and to develop individualized therapies. For example, the recently suggested role of Kir2.1 as a countercurrent to sarcoplasmic calcium reuptake might explain the arrhythmogenic mechanisms of ATS and its overlap with catecholaminergic polymorphic ventricular tachycardia (CPVT). Here we summarize current knowledge on the mechanisms of arrhythmias leading to sudden cardiac death in ATS. We first provide an overview of the syndrome and its pathophysiology, from the patient´s bedside to the protein, and discuss the role of essential regulators and interactors that could play a role in cases of ATS. The review highlights novel ideas related to some post-translational channel interactions with partner proteins that might help define the molecular bases of the arrhythmia phenotype. We then propose a new all-embracing classification of the currently known ATS loss-of-function mutations according to their position in the Kir2.1 channel structure and their functional implications. We also discuss specific ATS pathogenic variants, their clinical manifestations and treatment stratification. The goal is to provide a deeper mechanistic understanding of the syndrome toward the development of novel targets and personalized treatment strategies.

Ventricular Fibrillation: A Rare Initial Presentation of Thyrotoxic Periodic Paralysis

Thyrotoxic periodic paralysis is a life-threatening complication of hyperthyroidism characterized by transient episodes of muscle paralysis and hypokalemia, commonly seen in Asian men. We present a rare case of ventricular fibrillation as the initial presentation of thyrotoxic periodic paralysis. (Level of Difficulty: Intermediate.).

A Literature Review on Thyrotoxic Periodic Paralysis

Thyrotoxic periodic paralysis (TPP) is a rare disease of the muscles that presents with painless weakness of the muscles. The patients usually have hypokalemia and hyperthyroidism with elevations in the level of triiodothyronine (T3) and thyroxine (T4). The muscle weakness is usually transient, and the patients in many cases suffer from recurrent episodes of muscle paralysis. This flaccid muscle paralysis predominantly affects the proximal and lower extremities group of muscles more than the distal and upper extremity muscles. This condition is one of the drastic complications of Graves's disease and, unfortunately, may require admission and treatment in the critical care units. It is often not recognized during the initial attack in the American population as the prevalence is very low among the Caucasian population and people from North America. However, while the prevalence is extremely low in the Caucasian population, it is known to be 10 times more common among the Asian population when compared with the Caucasian population. Furthermore, while the diseases of the thyroid gland are more common in females, this rare disease predominantly affects male sex. It is treated by reversing the hypokalemia, which can in itself prove to be fatal if not corrected quickly, and this is followed by treatment to restore the euthyroid state. A literature review on this reversible cause of muscle weakness is very important to better understand this disease.

Thyrotoxic Periodic Paralysis-A Misleading Challenge in the Emergency Department

Despite its' life-threatening potential due to cardiac severe dysrhythmia in the context of severe hypokalemia, thyrotoxic periodic paralysis (TPP) often goes unrecognized. Although classically confined to young Asian men, it can occur irrespective of age, sex, and race. We report a short series of three cases of TPP as first presentation of Graves' disease in a young Caucasian male and in two Caucasian elderly and middle-aged women, respectively. The first patient developed malignant ventricular arrhythmias due to severe hypokalemia and was defibrillated, with recovery after prompt potassium correction and administration of antithyroid agents and propranolol. The other two cases developed persistent hypokalemia despite adequate potassium chloride (KCl) repletion, with slow recovery of motor deficit and serum potassium normalization up to day 5. In the first case, long-term euthyroid state was achieved via total thyroidectomy due to the presence of a suspicious nodule that proved to be malignant. In the other two cases, medical treatment was the choice of therapy for thyrotoxicosis. None experienced recurrent TPP. Thyroid hormone evaluation is mandatory in the presence of hypokalemic paralysis, even in the absence of clinical signs of thyrotoxicosis. If TPP is confirmed, initial therapy should comprise antithyroid drugs and propranolol, besides hypokalemia correction.

Pro-Arrhythmic Signaling of Thyroid Hormones and Its Relevance in Subclinical Hyperthyroidism

A perennial task is to prevent the occurrence and/or recurrence of most frequent or life-threatening cardiac arrhythmias such as atrial fibrillation (AF) and ventricular fibrillation (VF). VF may be lethal in cases without an implantable cardioverter defibrillator or with failure of this device. Incidences of AF, even the asymptomatic ones, jeopardize the patient's life due to its complication, notably the high risk of embolic stroke. Therefore, there has been a growing interest in subclinical AF screening and searching for novel electrophysiological and molecular markers. Considering the worldwide increase in cases of thyroid dysfunction and diseases, including thyroid carcinoma, we aimed to explore the implication of thyroid hormones in pro-arrhythmic signaling in the pathophysiological setting. The present review provides updated information about the impact of altered thyroid status on both the occurrence and recurrence of cardiac arrhythmias, predominantly AF. Moreover, it emphasizes the importance of both thyroid status monitoring and AF screening in the general population, as well as in patients with thyroid dysfunction and malignancies. Real-world data on early AF identification in relation to thyroid function are scarce. Even though symptomatic AF is rare in patients with thyroid malignancies, who are under thyroid suppressive therapy, clinicians should be aware of potential interaction with asymptomatic AF. It may prevent adverse consequences and improve the quality of life. This issue may be challenging for an updated registry of AF in clinical practice. Thyroid hormones should be considered a biomarker for cardiac arrhythmias screening and their tailored management because of their multifaceted cellular actions.