Parálisis periódica hipopotasémica familiar, Instituto Hondureño de Seguridad Social / Family Hypokalemic Periodic Paralysis, Social Security Institute of Honduras, Internal Medicine Service

La parálisis periódica hipopotasémica , es una enfermedad congénita autosómica dominante; predomina en sexo masculino, con concentraciones sanguíneas de potasio bajas. Objetivo: identificar la parálisis hipopotasémica familiar como un reto clínico para el diagnóstico y tratamiento del paciente. Presentación del caso clínico: masculino, en la tercera década de la vida; sin antecedentes personales, se presenta a emergencia con tetraparesia que inicia en manos, de distal a proximal, con posterior dificultad para la deambulación. Antecedentes familiares de su madre y hermana que habían padecido cuadro similar; exámenes de laboratorio: química sanguínea, Creatin fosfocinasa 1 481, Transaminasa glutámica oxaloacetica 46 U/L, Transaminasa glutámica pirúvica 36 U/L, Sodio 143 mg/dl, Potasio 2.6 mg/dl, Calcio 9.3 mg/dl. Tratamiento al ingreso 40 mEq de cloruro de potasio y 250 cc de solución salina normal 0.9%. Se realizó prueba terapéutica con cloruro de potasio y ver recuperación progresiva de la fuerza muscular, pruebas tiroideas descartan otras causas. Conclusión: la parálisis hipopotasémica se ha vuelto un diagnóstico poco sospechado en el ingreso de pacientes con tetraparesia, aunque el tratamiento rápidamente instaurado puede mejorar los síntomas y permite un estudio posterior de la etiología...(AU)

Debilidad muscular con hipokalemia e hipertiroidismo en un adolescente con síndrome de Down / Muscle weakness with hypokalemia and hyperthyroidism in an adolescent with Down syndrome

La hipokalemia aguda es una causa poco frecuente de debilidad muscular. La parálisis periódica tirotóxica es una complicación infrecuente de la tirotoxicosis, en sus diferentes etiologías, en la cual se produce hipokalemia por un flujo masivo de potasio al compartimiento intracelular, que provoca parálisis muscular, que afecta, principalmente, la musculatura proximal de los miembros inferiores. Es importante reconocer esta entidad para instaurar un tratamiento adecuado que incluya el rápido suplemento de potasio y el uso de beta-bloqueantes no selectivos. El tratamiento del hipertiroidismo subyacente y el retorno al estado eutiroideo es imprescindible para la resolución de los episodios de parálisis periódica tirotóxica. Aquí se presenta a un paciente de 13 años de edad con síndrome de Down que consultó por debilidad muscular de los miembros inferiores y trastorno de la marcha, asociada a hipokalemia aguda, en el que se realizó el diagnóstico de hipertiroidismo por enfermedad de Graves.

Acute hypokalemic paralysis is a rare cause of acute weakness. Thyrotoxic periodic paralysis (TPP) is an unusual complication of hyperthyroidism. It is characterized by sudden onset of hypokalemia condition resulting from a shift of potassium into cells and paralysis that primarily affects the lower extremities. Failure to recognize TPP may lead to improper management. Treatment of TPP includes replacing potassium rapidly, using nonselective beta-blockers and correcting the underlying hyperthyroidism as soon as possible. TPP is curable once euthyroid state is achieved. We describe a 13-year-old male with Down syndrome who presented with acute onset of lower extremity weakness secondary to acute hypokalemia and was found to have new onset Graves' disease.

Parálisis periódica hipocalémica: reporte de caso y revisión del tema / Hypokalemic periodic paralysis: A case report and a topic review

Las parálisis periódicas primarias son canalopatías poco frecuentes, de las cuales hacen parte: la parálisis periódica hipocalémica, la parálisis periódica hipercalémica y el síndrome Andersen-Tawil; son caracterizadas por ataques de debilidad muscular generalizada, con recuperación de la fuerza entre los ataques. Presentamos el caso de una mujer de 21 años con el segundo episodio de parálisis y documentación de hipocalemia, sin antecedentes de importancia, sin factores clínicos o paraclínicos que expliquen el trastorno electrolítico, con recuperación posterior de la fuerza al realizar tratamiento de la hipocalemia. Posteriormente se lleva a cabo una revisión del tema.

Primary periodic paralyses are rare channelopathies which include: hypokalemic periodic paralysis, hyperkalemic periodic paralysis, and Andersen-Tawil Syndrome. These entities are characterized by attacks of generalized muscle weakness and recovery of muscle strength between attacks. A case is presented of a 21-year-old woman who presented a second episode of paralysis and documented hypokalemia, with no important antecedents, with no clinical or diagnostic test factors which explain her electrolyte disorder, with recovery of muscle strength after receiving treatment for hypokalemia. A review of the topic was conducted.

Reference value of long-time exercise test in the diagnosis of primary periodic paralysis / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The long-time exercise test (ET) is used to diagnose the primary periodic paralyses (PPs). However the reference values of ET are many and various. This study aimed to investigate the reference value of long-time ET in the diagnosis of PPs.</p><p><b>METHODS</b>We recruited 108 healthy subjects, 68 patients with PPs, and 72 patients with other diseases for the study. The procedure of ET was made on the basis of the McManis' method. Electrical responses were recorded from right abductor digiti minimi (ADM) muscle when stimulation of the ulnar nerve at the wrist. After the compound muscle action potential (CMAP) was monitored, subjects were then asked to contract the muscle as strongly as possible for 5 minutes. CMAPs were recorded for 2 seconds immediately after cessation of exercise, then every 5 minutes for 10 minutes, and finally every 10 minutes for 50 minutes. In general, the CMAP amplitudes will fall below the pre-exercise levels in an hour. The largest decrease was calculated and used as results of ET.</p><p><b>RESULTS</b>The CMAP amplitude decreases had no significant differences between groups when the healthy adults were grouped according to age, gender, height, weight and test time. Decreases in PPs patients (57.76%) were significantly more than in healthy subjects (15.21%) and other disease patients (18.10%, P < 0.001). Receiver operating characteristic (ROC) curve analysis showed that the best threshold is 35.50%.</p><p><b>CONCLUSIONS</b>In the long-time exercise test, threshold of 35.50% for the CMAP amplitude decrease was identified for abnormal. The result is not influenced by age, gender, height, weight, and test time. About 7.4% of healthy subjects were abnormal in ET.</p>

Clinical and molecular genetic analysis of a family with normokalemic periodic paralysis / 中华儿科杂志

<p><b>OBJECTIVE</b>Periodic paralysis (PP) is one type of skeletal muscle channelopathies characterized by episodic attacks of weakness. It is usually classified into hyperkalemic periodic paralysis (HyperPP), hypokalemic periodic paralysis (HypoPP) and normokalemic periodic paralysis (NormoPP) based on the blood potassium levels. HypoPP is the most common type of these three and NormoPP is the rarest one. The aim of this study was to explore the clinical and genetic features of a Chinese family with normokalemic periodic paralysis (NormoKPP).</p><p><b>METHOD</b>Clinical features of all patients in the family with NormoKPP were analyzed. Genomic DNA was extracted from peripheral blood leukocytes and amplified with PCR. We screened all 24 exons of SCN4A gene and then sequence analysis was performed in those who showed heteroduplex as compared with unaffected controls.</p><p><b>RESULT</b>(1) Fifteen members of the family were clinically diagnosed NormoKPP, and their common features are: onset within infacy, episodic attacks of weakness, the blood potassium levels were within normal ranges, high sodium diet or large dosage of normal saline could attenuate the symptom. One muscle biopsy was performed and examination of light and electronic microscopy showed occasionally degenerating myofibers. (2) Gene of 12 patients were screened and confirmed mutations of SCN4A genes--c. 2111 T > C/p. Thr704Met.</p><p><b>CONCLUSION</b>The study further defined the clinical features of patients with NormoKPP, and molecular genetic analysis found SCN4A gene c. 2111 T > C/p. Thr704Met point mutation contributed to the disease. In line with the autosomal dominant inheritance laws, this family can be diagnosed with periodic paralysis, and be provided with genetic counseling. And the study may also help the clinical diagnosis, guide treatment and genetic counseling of this rare disease in China.</p>

A Practical Approach to Genetic Hypokalemia

Mutations in genes encoding ion channels, transporters, exchangers, and pumps in human tissues have been increasingly reported to cause hypokalemia. Assessment of history and blood pressure as well as the K+ excretion rate and blood acid-base status can help differentiate between acquired and inherited causes of hypokalemia. Familial periodic paralysis, Andersen's syndrome, congenital chloride-losing diarrhea, and cystic fibrosis are genetic causes of hypokalemia with low urine K+ excretion. With respect to a high rate of K+ excretion associated with faster Na+ disorders (mineralocorticoid excess states), glucoricoid-remediable aldosteronism and congenital adrenal hyperplasia due to either 11beta-hydroxylase and 17alpha-hydroxylase deficiencies in the adrenal gland, and Liddle's syndrome and apparent mineralocorticoid excess in the kidney form the genetic causes. Among slow Cl- disorders (normal blood pressure, low extracellular fluid volume), Bartter's and Gitelman's syndrome are most common with hypochloremic metabolic alkalosis. Renal tubular acidosis caused by mutations in the basolateral Na+/HCO3 - cotransporter (NBC1) in the proximal tubules, apical H+-ATPase pump, and basolateral Cl-/HCO3 - exchanger (anion exchanger 1, AE1) in the distal tubules and carbonic anhydroase II in both are genetic causes with hyperchloremic metabolic acidosis. Further work on genetic causes of hypokalemia will not only provide a much better understanding of the underlying mechanisms, but also set the stage for development of novel therapies in the future.

[Cardiac manifestation of normokatemic periodic paralysis in 21 years old male in Kermanshah]

Normokalemic periodic paralysis is an autosomal dominant disorder involving the abnormal function of skeletal muscle's voltage-gated alpha-subunits. It is characterized by paralysis attack of varying severity with concomitant normal serum potassium concentration. Although normokalemic periodic is well established in the literature, but its cardiac manifestations are very rare. We present 21 years old age male, which referred to Imam Ali hospital with severe palpitation, atypical angina and flaccid quadric paralysis. Electrocardiographic manifestation was first-degree AV block. Bijeminated ventricular extrasystole and severe ST-T change in pericardial leads. Initial potassium level was 4 meq/l, CPK and aldolase level was normal. Echocardiography and exercise test were normal. After four days administration of acetazolamide, his weakness was disappeared and ECG became normal. He discharged from hospital with normal neurological examination and effective treatment outcome

Clinical Diversity of SCN4A-Mutation-Associated Skeletal Muscle Sodium Channelopathy

BACKGROUND AND PURPOSE: Mutations of the skeletal muscle sodium channel gene SCN4A, which is located on chromosome 17q23-25, are associated with various neuromuscular disorders that are labeled collectively as skeletal muscle sodium channelopathy. These disorders include hyperkalemic periodic paralysis (HYPP), hypokalemic periodic paralysis, paramyotonia congenita (PMC), potassium-aggravated myotonia, and congenital myasthenic syndrome. This study analyzed the clinical and mutational spectra of skeletal muscle sodium channelopathy in Korean subjects. METHODS: Six unrelated Korean patients with periodic paralysis or nondystrophic myotonia associated with SCN4A mutations were included in the study. For the mutational analysis of SCN4A, we performed a full sequence analysis of the gene using the patients' DNA. We also analyzed the patients' clinical history, physical findings, laboratory tests, and responses to treatment. RESULTS: We identified four different mutations (one of which was novel) in all of the patients examined. The novel heterozygous missense mutation, p.R225W, was found in one patient with mild nonpainful myotonia. Our patients exhibited various clinical phenotypes: pure myotonia in four, and PMC in one, and HYPP in one. The four patients with pure myotonia were initially diagnosed as having myotonia congenita (MC), but a previous analysis revealed no CLCN1 mutation. CONCLUSIONS: Clinical differentiating between sodium-channel myotonia (SCM) and MC is not easy, and it is suggested that a mutational analysis of both SCN4A and CLCN1 is essential for the differential diagnosis of SCM and MC.

The construction and preliminary investigation of the cell model of a novel mutation R675Q in the SCN4A gene identified in a Chinese family with normokalemic periodic paralysis / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To construct and investigate the cell model of a novel mutation R675Q in the skeletal muscle Na channel type 4 alpha subunit gene (SCN4A) identified from a Chinese family with normokalemic periodic paralysis.</p><p><b>METHODS</b>cDNA encoding the adult isoform of SCN4A was used as a template for in vitro site-directed mutagenesis by PCR method. The mutated plasmid was transiently transfected into HEK-293 cells by calcium phosphate precipitation. Twenty four and 48 hours after transfection, the expression level of SCN4A was detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. Whole cell voltage-clamp recording was used to study the current of sodium channels.</p><p><b>RESULTS</b>The site-mutagenesis of the plasmid was confirmed by sequencing. The expression of SCN4A gene was significantly elevated 24 h and 48 h after transfection. The relative current of R675Q is smaller than that of wide type before reaching peak current under the same test voltage, but larger than that of wild type current after reaching peak current. They both had the largest peak current under 0 mV test pulse.</p><p><b>CONCLUSION</b>A cell model of normokalemic periodic paralysis was successfully constructed. The R675Q mutation of the SCN4A gene enhances the activation and inactivation of the sodium channel, and the S4 transmembrane segment may have intimate relationship with the attack of weakness in normoKPP patients.</p>

Exercise test on the patients with normokalaemic periodic paralysis from a Chinese family with a mutation in the SCN4A gene / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Normokalaemic periodic paralysis (normoKPP) is characterized by transient and recurrent myoasthenia, and some patients also show muscle stiffness induced by cold exposure (paramyotonia congenita, PMC). It is caused by a mutation in the muscle voltage gated sodium channel alpha subunit (SCN4A) gene. Due to the diversity of the clinical manifestations of patients, it is difficult for clinicians to differentiate some of patients with atypical normoKPP from those who suffer from other periodic paralysis and nondystrophic myotonia. So far, for normoKPP there are almost no ways to assist definite diagnosis besides genetic screening. This research was designed to evaluate an exercise test (ET) in confirming the diagnosis of normoKPP and in assessing the therapeutic effectiveness of some drugs on this disease.</p><p><b>METHODS</b>ET, described by McMains, was performed on six subjects from a Chinese family, including four patients with overlapping disease of normoKPP and PMC caused by a mutation of SCN4A Met1592Val that is identified by genetic analysis and two normal control members. The change of compound muscle action potential (CMAP) was recorded. Besides the family, two patients were also tested during treatments with acetazolamide.</p><p><b>RESULTS</b>All patients showed a slight increase in CMAP immediately after exercise, followed by an abnormal gradual decline, which reached its nadir 25-30 minutes after exercise. CMAP amplitude dropped by more than 40% in patients but less than 23% in controls. In the patients who received treatment with acetazolamide, the change of CMAP amplitude was less than 28% and, at any fixed times, less than pretreatment values.</p><p><b>CONCLUSIONS</b>The ET may be used as a predictive, easy and reliable method of diagnosing normoKPP under conditions without genetic screening help, and is an objective way to evaluate the therapeutic effectiveness. According to different response patterns, the ET may also be helpful in reducing the scope of genetic screening.</p>

Fatal thyrotoxic periodic paralysis with normokalemia.

We present a 10-year-old girl who presented to our emergency services with difficulty in breathing of 2-days duration and progressive weakness of a month's duration. In a previous admission elsewhere, she had not been detected to have hyperthyroidism or electrolyte abnormalities. On admission, the child was in hypercapnic respiratory failure with tachycardia and hepatomegaly. A small goiter as well as signs of thyrotoxicosis were present. Laboratory investigations showed anemia, mildly elevated liver enzymes and serum potassium of 4.8mEq/L. Despite intubation and ventilation and other supportive management including propranolol, the patient could not be saved. Post-mortem biopsy of the thyroid showed diffuse hyperplasia of the follicles and muscles showed evidence of thyroid myopathy.

A case report of familial periodic paralysis.

A 20-year-old male was brought to the hospital with the complaints of severe weakness and inability to move the limbs of 12 hours duration. For the last 2 years he had the same episodes with spontaneous recovery. Family history strongly suggested involvement of other members of the family. Physical examination did not suggest any neurological deficit. All investigations were normal except serum potassium level being 2.2 meq/l during attack and 3.4 meq/l after the attack. He was treated with oral acetazolamide and potassium chloride. The case was diagnosed to be familial periodic paralysis belonged to the group 'episodic myasthenia'.

Caracterización electrocadiográfica en estudiantes de ciencias para la salud de Manizales, según antecedentes familiares de infarto de miocardio / Electrocardiographic characterization in students of sciences of the health of Manizales, according to familiar antecedents of myocardium infarct

Introducción: El Infarto agudo de Miocardio (IAM), constituye una de las principales causas de muerte y discapacidad en el medio, es por esto que su diagnóstico es de vital importancia. La utilización del electrocardiograma contiene un invaluable pronóstico de información relacionada con: tamaño del corazón, desviación del segmento S-T, duración de QRS y localización del infarto. Esta información sumada a la predicción clínica, debe ser valorada para facilitar la mejor opción de tratamiento -Conclusiones: En este estudio no se encontró correlación entre características electrocardiográficas que hicieran pensar en un IAM personal con antecedentes familiares de patología cardíaca posiblemente debido al período tan corto con el que se contó para realizar la investigación, sin posibilidad de realizar un seguimiento a estos pacientes...

Aetiological, clinical and metabolic profile of hypokalaemic periodic paralysis in adults: a single-centre experience.

BACKGROUND: Hypokalaemic periodic paralysis constitutes a heterogeneous group of disorders that present with acute muscular weakness. In this analysis, we discuss the aetiological factors that appear to be more common in the Indian population. METHODS: From 1995 to 2001, 31 patients presented with periodic paralysis (mean age 34.5 years, range 11-68 years). Of the 31 patients, 19 were men. The clinical and laboratory data of these patients were analysed. Patients were investigated for possible secondary causes of hypokalaemla. RESULTS: There were 13 patients (42%) with renal tubular acidosis, 13 with primary hyperaldosteronism (42%), 2 each with thyrotoxic periodic paralysis and sporadic periodic paralysis, and I with Gitelman syndrome. Of the 13 patients with renal tubular acidosis, 10 had proximal and 3 distal renal tubular acidosis. Three of these patients with renal tubular acidosis had Sjogren syndrome. The patients diagnosed to have renal tubular acidosis had significantly lower serum bicarbonate (18.7 [14.6] v. 29.6 [5.0] mEq/L; p < 0.05) and higher levels of chloride (107.5 [6.0] v. 99.5 [3.4] mEq/L; p < 0.05) compared with those who had primary hyperaldosteronism, although the potassium values were similar (2.4 [0.65] v. 2.26 [0.48] mEq/L; p = 0.43). All patients with primary hyperaldosteronism had hypertension at presentation and were proven to have adrenal adenomas. CONCLUSION: A significant number of patients in this study had secondary and potentially reversible causes of hypokalaemic periodic paralysis. The common causes were renal tubular acidosis and primary hyperaldosteronism. A detailed work-up for secondary causes should be undertaken in Indian patients with hypokalaemic periodic paralysis.

Genetics of Channelopathy: Familial Periodic Paralysis

Familial periodic paralysis (FPP) is inherited as a dominant trait, and the intermittent failure to maintain the skeletal muscle resting potential is due to mutations in the genes coding for the voltage-gated ion channels. Because several variants of FPP have been delineated on the bases of clinical features, the expectation was that these variants might be due to involvement of different classes of ion channels. The reality of the situation has proven to be more complicated. Mutation-induced defects in the same channel may give rise to diverse phenotypes (phenotypic heterogeneity) and, conversely, mutation in different channel genes may produce a common phenotype (genetic heterogeneity). Regardless of which type of ion channel is defective, the final common pathway is the depolarization-induced loss of muscle excitability; gain-of-function defect in voltage-gated Na channel may cause myotonia, periodic paralysis or both, clinical features of hyperkalemic periodic paralysis and paramyotonia congenita, and loss-of-function defects in voltage-gated Na and Ca channel and K channel may be responsible for periodic paralysis, cardiac arrhythmia or both in hypokalemic periodic paralysis or Andersen's syndrome, respectively. This review focuses on the clinical features, molecular genetic defects, and pathophysiologic mechanisms that underlie FPP.

The mutation V781I in SCN4A gene exists in Chinese patients with normokalemic periodic paralysis / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>In this report are reviewed two unrelated patients with typical normokalemic periodic paralysis (normoKPP) features and the results of screening the SCN4A gene for the disease-related mutation.</p><p><b>METHODS</b>Two sporadic cases with normoKPP were screened for previously known mutations in SCN4A gene (T704M, A1156T, M1360V, I1495F, M1592V) that lead to hyperKPP; denaturing high performance liquid chromatography (DHPLC) was used. Then the rest exons of SCN4A gene were screened by DHPLC, and sequence analysis was performed on those with DHPLC chromatogram variation when compared with unaffected control.</p><p><b>RESULTS</b>Two cases and one patient's father were detected with V781I, which was proved to be a singular missense mutation in SCN4A gene.</p><p><b>CONCLUSION</b>The mutation V781I exists in Chinese patients with normoKPP and may be responsible for normoKPP.</p>

Paralisia periódica / Periodic paralyses: clinical and molecular basis of secundary form a thyrotoxic

Objetivos: Determinar o índice de dano (ID) através do Systemic Lupus Iinternational Collaborating Clinics/ACR Damage Index for Systemic Lupus Erythematosus (SLICC/ACR-DI), em pacientes com lúpus eritematoso sistêmico (LES), atendidos em hospital universitário e avaliar a possível associação do nível socioeconômico (NSE), idade de início da doença, manifestações clínicas, alterações laboratoriais e dano. Pacientes e Métodos: Cento e setenta pacientes com LES foram entrevistados para obtenção de dados demográficos e socioeconômicos (idade, cor, sexo, escolaridade, estado civil, tipo de moradia, renda familiar e per capita e classificação econômica). A revisão de prontuários foi realizada, para avaliação dos aspectos clínicos e laboratoriais da doença [idade do início ( 16 anos;  21 anos) e idade ao diagnóstico da doença, tempo de doença (TD); critérios de classificação ACR, presença de autoanticorpos e hipocomplementemia)]. Os escores do SLICC foram obtidos através da entrevista com o paciente, avaliação clínica e revisão de prontuários. Análise estatística: A análise univarida foi feita com os testes de Mann-Whitney, Fisher, qui-quadrado e Kruskal-Wallis. 0 coeficiente de Spearman foi utilizado para avaliar possível correlação de SLICC com: tempo de doença, tempo de início de doença, idade ao diagnóstico, idade atual, número de critérios ACR ao diagnóstico e ao longo da doença (número total), número de pulsos com ciclofosfamida (CFM) e MPS (metilprednisolona), classificação econômica, escolaridade e salário mínimo por pessoa. No modelo inicial de regressão logística foram incluídas as seguintes variáveis: tempo de doença, número de critérios do ACR ao diagnóstico e número total de critérios, hipocomplementemia, anticorpos anti-DNAn, anticorpos aCl, pulsoterapia com MPS e/ou pulsoterapia com CFM. Valores com p<0,05 foram considerados estatisticamente significantes. Resultados: Cento e dez pacientes (64,5 por cento) apresentaram algum dano ao longo da doença, A média de SLICC foi de 1,26 ±1,38 e a média do TD foi de 90,9 meses. 0 dano cutâneo (17,6 por cento) foi o mais freqüente, seguido do músculoesquelético (15,3 por cento), neuropsiquiátrico (14,7 por cento), vascular periférico (11,2 por cento) e renal (9,4 por cento)...

Thyrotoxic periodic paralysis: an overview

Thyrotoxic periodic paralysis [TPP] is a fairly common manifestation of hyperthyroidism in Asian populations, with an incidence of about 1.9% in thyrotoxic patients, but it is rarely diagnosed among Caucasians and blacks in the Western world. The diagnosis often can be made on the basis of the clinical manifestations alone. Sometimes, periodic paralysis precedes hyperthyroidism or occurs in silent hyperthyroidism. As a result, physicians may easily overlook it even when life-threatening hypokalemia is present. The pathophysiology of this disorder is still not well understood. Correction of the thyrotoxic state is the definitive treatment. Potassium supplementation, propranolol, and spironolactone may be helpful both in the acute state and in preventing attacks

Paralisia periódica tireotóxica (PPT) / Thyrotoxic periodic paralysis

A paralisia periódica tireotóxica (PPT) é caracterizada por episódio recorrentes de fraqueza muscular, de intensidade variável, associada com hiperfunçäo tireodiana, atingindo, de forma muito preferencial, jovensasiáticos do sexo masculino. É associada, via de regra, com baixos níveis séricos de potássio e, frequentemente, desencadeada por exercícios físicos e ingestäo de carboidratos. Nós descrevemos um caso da doença em um jovem brasileiro, do sexo masculino e sem ascendência asiática, que se apresentou com um episódio de paralisia muscular e sem diagnóstico prévio de hipertireodismo. Foram encontrados níveis aumentados de T3, T4 e T4 livre e o TSH estava diminuido devido a um bócio tóxico difuso. A PPT deve ser considerada no diagnóstico diferencial de todos os episódios agudos de paralisia muscular em pacientes jovens mesmo em nosso país. A determinaçäo de potássio sérico e hormônios tiroideanos auxiliam o diagnóstico. O diagnóstico preciso é importante para o tratamento antitiroideano que evita episódio subsequentes de paralisia muscular