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CONTEXT: Thyrotoxic periodic paralysis (TPP) is a relatively common complication seen in Asian hyperthyroid patients. However, it is a rare occurrence to find a TPP case comprised of acute hypercapnic respiratory failure in patients with painless thyroiditis. PATIENT: A 29-year-old Chinese man presented with flaccid paralysis of all four limbs and he was brought to emergency room. Severe hypokalemia was found on admission. Although treatment had been initiated with potassium chloride supplementation, he went on to develop acute hypercapnic respiratory failure likely due to muscle fatigue. The patient was intubated for mechanical ventilatory support. Once his serum potassium levels were normalized, he was able to be weaned off ventilator support. Thyroid function tests showed elevated free thyroxine concentration and low thyroid-stimulating hormone concentration. He underwent a thyroid uptake scan with 131I which revealed decreased uptake rate of thyroid area. Based on the patient's clinical presentation and associated findings, we diagnosed him with TPP due to painless thyroiditis. We have reviewed TPP cases caused by painless thyroiditis and TPP cases associated with acute hypercapnic respiratory failure. CONCLUSION: It is important to note that potentially fatal complications such as acute hypercapnic respiratory failure might occur in acute attacks of TPP even in cases of TPP due to painless thyroiditis.

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OBJECTIVE To screen for mutations in a Chinese pedigree affected with hypokalemic periodic paralysis. METHODS The proband and nine family members were enrolled for the analysis of CACNA1S and SCN4A gene mutations. Genomic DNA was extracted from peripheral blood samples. The coding regions of the two genes were amplified with PCR and subjected to Sanger sequencing. Potential impact of suspected mutations was predicted with Bioinformatics software. The mutations were also verified among 100 healthy controls. RESULTS The proband and 5 family members (including 5 males and 1 female) had presented with episodes of flaccid paralysis accompanied by low serum potassium. Genetic testing has identified a c.664C>T (p.Arg222Trp) mutation in the proband, which has been reported previously. The same mutation was identified in other 5 affected members from the family. No mutation of the CACNA1S gene was detected. CONCLUSION The c.664C>T mutation of the SCN4A gene probably underlies the hypokalemic periodic paralysis in this family. All patients from the family have shown a complete penetrance of the disease.

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Thyrotoxic hypokalemic periodic paralysis (THPP) is an endocrine emergency marked by recurrent attacks of muscle weakness associated with hypokalemia and thyrotoxicosis. Asiatic male patients are most often affected. On the other hand, African descents rarely present this disease. The case described shows an afrodescendant patient with hypokalemia and tetraparesis, whose diagnosis of hyperthyroidism was considered during this crisis. The THPP, although rare, is potentially lethal. Therefore, in cases of flaccid paresis crisis this diagnosis should always be considered, especially if associated with hypokalemia. In this situation, if no previous diagnosis of hyperthyroidism, this should also be regarded.

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BACKGROUND: Thyreotoxic hypokalaemic periodic paralysis (THPP) is a rare and potentially life-threatening syndrome. It principally affects men of East-Asian origin and has rarely been described in a white person. CASE DESCRIPTION: A 34-year-old Dutch man, suffering from Graves' disease, presented with weakness in his lower limbs. Laboratory investigation showed severe hypokalaemia (1.8 mmol/l) and increased creatinine kinase levels. An electrocardiogram showed atrial fibrillation with a prolonged QTc-interval. The patient was admitted, cardiac rhythm was monitored, and he received potassium supplements. Laboratory investigation of thyroid function showed thyrotoxicosis. The patient was treated with propranolol and thiamazol. At follow-up, thyroid function, potassium levels and muscle strength had normalized. CONCLUSION: Hypokalaemia due to thyrotoxicosis should be considered in cases of unexplained paralysis. The treatment of THPP consists of treating for hyperthyroidism plus propranolol. Since the hypokalaemia is self-limiting, potassium supplementation is only necessary in cases of rhythm disturbances or cardiac-conduction disturbances. Despite adequate treatment, there is a risk of recurrence. Regular monitoring is indicated until euthyroidism is achieved.

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A paralisia periódica hipocalêmica tireotóxica (PPHT) é uma urgência endocrinológica caracterizada por ataques recorrentes de fraqueza muscular, associados à hipocalemia e à tireotoxicose. Essa patologia ocorre mais frequentemente em pacientes do sexo masculino, de origem asiática, sendo rara sua apresentação em pessoas de ascendência africana. O caso descrito mostra um paciente afrodescendente que apresentou tetraparesia associada à hipocalemia. Durante esse episódio foi realizado o diagnóstico de hipertireoidismo. A PPHT, embora rara, é potencialmente letal. Portanto, em casos de crises de paresias flácidas, essa hipótese diagnóstica deve ser sempre considerada, principalmente se associada à hipocalemia. Nessa situação, se não houver diagnóstico prévio de hipertireoidismo, este também deve ser considerado.

Thyrotoxic hypokalemic periodic paralysis (THPP) is an endocrine emergency marked by recurrent attacks of muscle weakness associated with hypokalemia and thyrotoxicosis. Asiatic male patients are most often affected. On the other hand, African descents rarely present this disease. The case described shows an afrodescendant patient with hypokalemia and tetraparesis, whose diagnosis of hyperthyroidism was considered during this crisis. The THPP, although rare, is potentially lethal. Therefore, in cases of flaccid paresis crisis this diagnosis should always be considered, especially if associated with hypokalemia. In this situation, if no previous diagnosis of hyperthyroidism, this should also be regarded.

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Thyrotoxic periodic paralysis (TPP) is a rare metabolic disorder characterised by muscular weakness and paralysis in predisposed thyrotoxic patients. Although patients with TPP are almost uniformly men of Asian descent, cases have been reported in Caucasian and other ethnic populations. The rapid increase in ethnic diversity in Western and European nations has led to increase in TPP reports, where it was once considered exceedingly rare. Correcting the hypokalaemic and hyperthyroid state tends to reverse the paralysis. However, failure to recognise the condition may lead to delay in diagnosis and serious consequences including respiratory failure and death. We describe a young man who was diagnosed with hyperthyroidism who presented with acute paralysis. The clinical characteristics, pathophysiology and management of TTP are reviewed.

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We report a case of a 39 year-old Asian man in whom profound lower limb paralysis, along with severe hypokalemia and electrocardiographic changes, were the presenting features of Graves' disease (GD)-related thyrotoxicosis. Rapid recognition and management of the disorder were the key factors to avoid fatal hypokalemia-induced cardiac arrhythmias and promptly restore patient's capacity to ambulate.

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BACKGROUND: Thyrotoxic, hypokalaemic periodic paralysis (TPP) is a reversible cause of severe muscle weakness that occurs in a small minority of thyrotoxic patients. Most cases to date have been reported in Asian men. AIMS: To evaluate the ethnic distribution of patients with TPP. METHODS: Retrospective analysis of all patients presenting with thyrotoxicosis and hypokalaemia with paralysis to two New Zealand hospitals. RESULTS: Seventy-one per cent of the 21 patients with TPP were of Polynesian ethnicity (Maori and Pacific Islander), 24% Asian and 5% European. Based on population demographics, these figures suggest a 37-fold overrepresentation for Polynesians and 159-fold for Asians compared with New Zealand Europeans. CONCLUSION: Polynesian, in addition to Asian people, are two ethnic groups at particular risk of TPP, and this condition must be considered in the differential diagnosis for patients presenting to the emergency department with severe hypokalaemia and weakness.

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OBJECTIVE: Thyrotoxic periodic paralysis (TTP) has been associated with genetic variations in the gene encoding the alpha 1 subunit of the L-type calcium channel (CACNA1S). Mutations in CACNA1S are known to account for the majority of cases of familial hypokalaemic periodic paralysis (HOKPP). In this study we have examined 48 genetic polymorphisms in the CACNA1S gene and genotyped a tagging set of representative polymorphisms to determine the role of this gene in TPP. DESIGN AND PATIENTS: A genetic association study was carried out with 98 TPP patients and 162 male thyrotoxic controls. Among 47 polymorphisms evaluated for linkage disequilibrium (LD) and the spectrum of haplotypes in the Chinese population, 31 were selected as tagging single-nucleotide polymorphisms (SNPs) for genotyping the whole sample. A new genotyping protocol was used to analyse an insertion/deletion (I/D) polymorphism. RESULTS: We studied the LD among 47 polymorphisms in the CACNA1S gene, which comprised a set of high-density markers with an average of one SNP every 2 kb. Subsequently, 31 tagSNPs were genotyped for all the samples. The gene is composed of three LD blocks. With this block structure, we were confident that variations of the gene were comprehensively covered by the tagSNPs. No significant association was found between the polymorphisms and TPP. CONCLUSION: We established the LD structure of this calcium channel subunit gene (CACNA1S) for the first time. However, its genetic variations are not associated with TPP in Chinese patients.

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A 35-year-old Malaysian man presented with rapid onset of flaccid quadriparesis associated with nausea and vomiting. General blood tests revealed severe hypokalaemia (serum potassium 1.5 mmol/L) and hypophosphataemia (serum phosphate 0.29 mmol/L) as a potential cause of the flaccid paralysis. Arterial blood gases showed mixed acid base disturbance of respiratory alkalosis and metabolic acidosis with hyperlactataemia. Thyrotoxic periodic paralysis (TPP) was suspected as the underlying cause of this presentation and thyroid function tests showed severe hyperthyroid results (free T4 > 77.2 pmol/L, free T3 19.3 pmol/L, thyroid-stimulating hormone [TSH] < 0.05 mIU/L). Treatment with intravenous potassium and phosphate infusion and oral propranolol resulted in rapid resolution of his symptoms. A discussion of the clinical and pathophysiological features and treatment of TPP (a very rare encounter in UK clinical practice) is presented, and to our knowledge associated hyperlactataemia has not been previously described.

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OBJECTIVE: Mutation screening was performed on two Chinese families with HOKPP to locat the corresponding mutations and to specify the clinical features associated with the mutation. METHODS: Target-exon PCR and direct sequencing were used to screen mutation in the CACNA1S and SCN4A gene of all numbers of the two families. The clinical features of patients were summary. RESULTS: A heterozygous point mutation 2015G-->A causing R672H in the SCN4A was found in five patients and five normal relatives of the two families. Features of R672H mutation are incomplete penetrance, especially non-penetrance of phenotype in women and potassium is effective, but acetazolamide is not. CONCLUSION: The SCN4A R672H mutation exists in the Chinese family with HOKPP.

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We report the case of a caucasian patient with a presentation of a periodic paralysis associated with hypokalaemia disclosing Graves' disease. Major pathophysiologics hypothesis are discused in order to explain relationships between hyperthyroidism and paralysis through a disturbance of the excitability of the muscle fibres. A genetic predisposition explain the high incidence of this affection in asiatic population while it is uncommon in caucasian race. Potassium supplementation is not needed in order to correct hypokalaemia except in case of cardiac disturbances. Treatment by beta-blockers is advisable with the specific treatment of hyperthyroidism.

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BACKGROUND: Thyrotoxic periodic paralysis (TPP) is a complication of hyperthyroidism. MATERIALS AND METHODS: We describe two patients with TPP. RESULTS: A 26-year-old man from Vietnam had weight loss, tachycardia, palpitations and heat intolerance for five months. Episodic leg and arm weakness developed three months after debut of symptoms. The second patient, a 23-year old woman from the Philippines, had had episodic leg weakness in the evenings after dinner for three weeks. Her attacks resolved spontaneously overnight. Physical examination of both patients revealed tachycardia and symmetrical proximal weakness involving both arms and legs. ECG and electrolyte analysis indicated a severe hypokalaemia; thyroid function tests showed hyperthyroidism. Both patients were diagnosed as having Graves' thyrotoxicosis and TPP. They were initially treated with propranolol and subsequently with carbimazole. The first patient had recurrence of thyrotoxicosis and paralysis after 16 months, whereas the second patient has remained symptom-free. INTERPRETATION: TPP is most common in Asian males, very few cases are reported in females. In Western countries TPP is rare, but with increasing immigration, TPP is likely to occur more frequently.

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Thyrotoxic periodic paralysis is a thyroid-related disorder that is manifested as recurrent episodes of hypokalemia and muscle weakness lasting from hours to days. The periodic paralysis has been associated with thyrotoxicosis from various etiologies. Although the incidence of the disorder is relatively higher among Asians, it has been reported in many other ethnic groups. We review the literature and report the ninth and tenth cases of thyrotoxic periodic paralysis in black patients.

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