Insulin resistance in subjects with a history of thyrotoxic periodic paralysis (TPP)

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.

Thyrotoxic Periodic Paralysis in a Samoan Male With Metabolic Acidosis: A Case Report and Review of the Literature

Thyrotoxic periodic paralysis (TPP) is a rare disorder characterized by muscle paralysis, thyrotoxicosis, and hypokalemia. It commonly manifests as paralysis of both proximal and distal upper and lower limbs, and if left untreated, may progress to respiratory failure or cardiac arrhythmias. It is most common in Asian males and is frequently precipitated by strenuous exercise, high carbohydrate diet, stress, corticosteroid therapy, or alcohol. Early diagnosis of TPP is crucial as the condition may be reversible with oral or IV potassium replacement therapy, and management of the underlying hyperthyroidism. We describe a Samoan man in his 30s who presented with acute onset lower extremity paralysis. Laboratory investigations revealed low serum potassium of 2.2 mEq/L (reference range 3.5-5.0 mEq/L) and thyrotoxicosis with a low (thyroid stimulating hormone (TSH) of <0.07 uIU/mL (reference range 0.27-4.20 uIU/mL) and an elevated free T4 of 5.4 ng/dL (reference range 0.9-2.1 ng/dL). He was treated with both oral and IV potassium chloride as well as propranolol and regained full strength in his extremities. While rare, TPP is a reversible complication of thyrotoxicosis and a high index of suspicion in clinical practice is essential to prevent adverse outcomes.

Hyperandrogenism and Hypokalemic Thyrotoxic Periodic Paralysis in a North American Adolescent Girl

We present a unique case of hypokalemic thyrotoxic periodic paralysis (TPP) in an adolescent girl in North America. TPP is a rare but dangerous complication seen in thyrotoxic patients characterized by hypokalemia and acute proximal symmetric lower-extremity weakness. It is an especially rare phenomenon in pediatrics, with roughly 20 case reports described in adolescents worldwide; the majority are male. Our patient is a 14-year-old Asian girl with biochemical hyperandrogenism and known Graves disease who presented with an acute episode of lower-extremity weakness after eating a carbohydrate-rich meal. Laboratory workup revealed hypokalemia, hypomagnesemia, an undetectable thyrotropin, and hyperthyroxinemia. Electrolyte derangements responded well to supplementation, and the muscle weakness resolved with electrolyte normalization. Following improvement in thyroid function, the patient underwent thyroidectomy for definitive management of Graves disease. As TPP is potentially exacerbated by higher androgen and insulin levels, we suspect that with increasing rates of obesity and polycystic ovary syndrome, the incidence of TPP among adolescents may increase. It is therefore critically important that there is awareness and recognition of this serious diagnosis among all health care providers.

Acute Flaccid Tetraparesis after COVID-19 Infection: Think of the Thyroid

A previously well 32-year-old Chinese male presented with acute bilateral upper and lower limb paralysis upon waking, ten days after the onset of COVID-19 infection. Examination revealed areflexia over all four limbs, associated with reduced muscle strength, but no sensory or cranial nerve deficit. Initial concern was Guillain-Barre syndrome given the acute flaccid paralysis following COVID-19 infection. However, investigations revealed severe hypokalaemia (1.7 mmol/L) and primary hyperthyroidism. He was treated for thyrotoxic periodic paralysis (TPP) with β-blockers, antithyroid medications, and intravenous potassium chloride (KCl). Despite frequent monitoring of potassium, rebound hyperkalaemia occurred with prompt resolution of 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.

Impact of first-line treatment choice on long-term outcomes of hyperthyroid Graves' disease patients with thyrotoxic periodic paralysis

Background

Thyrotoxic periodic paralysis (TPP) is a unique manifestation of Graves’ disease. While it is uncommon in Asian, it is extremely rare in Caucasian patients (0.1–0.2%). Previous studies suggested that TPP indicate more severity of Graves’ disease and definitive treatments should be used to prevent relapses.

Aim

To describe clinical features and impact of first-line treatment on long-term outcomes of TPP patients.

Method

A retrospective cohort study over 35 years (1985–2019) of TPP from Graves’ disease patients was conducted. All cases were analyzed and their clinical courses were compared between those who received anti-thyroid drugs (ATD) versus radioactive iodine (RAI) as a primary treatment. None of them underwent surgery.

Results

A total of 2964 hyperthyroid Graves’ disease patients were treated and followed-up at least 3 months over the study period. TPP was identified in 63 cases (2.1%) of all patients. There were 60 males and only 3 females with age at presentation of 35.0 ± 8.2 years. TPP was the first presentation of hyperthyroid Graves’ disease in 82.5% of them. During the acute attack of TPP, all patients presented with bilateral lower limb flaccid weaknesses with median serum potassium of 2.1 mmol/L. No fatal TPP cases were found. RAI was selected as primary treatment in 27 patients (42.9%). Nearly all RAI-treated patients rendered hypothyroidism with the median RAI dose at 15 mCi. No patients who were in remission after RAI treatment developed recurrent attack of TPP. In the remaining 36 ATD-treated patients with mean follow-up time at 9.1 years, relapse was found in 10 patients (27.8%) after the drug discontinuation and 6 patients suffered recurrent TPP. Only 8 ATD-treated TPP patients (22.2%) went into remission.

Conclusions

TPP is a rare complication of hyperthyroid Graves’ disease. Definitive treatment with RAI or thyroidectomy should be employed to prevent relapse and further attacks of TPP.

Thyrotoxic periodic paralysis presenting in an African-American teenage male: case report

Background

Thyrotoxic periodic paralysis is a rare complication of hyperthyroidism and is associated with hypokalemia and muscle paralysis. This condition is most commonly seen in Asian men.

Case presentation

We report on a 14-year-old African American male with Graves’ disease and intermittent asthma who presented with bilateral leg weakness. The patient demonstrated signs of thyrotoxicosis and laboratory evaluation revealed hypokalemia and hyperthyroidism. Following the administration of potassium supplementation clinical status improved and the patient was discharged home on a high dose of methimazole and propranolol. At a 6-month follow up visit, he was found to be clinically euthyroid and demonstrated no signs of hyperthyroidism or muscle weakness.

Conclusion

Children presenting with weakness and hypokalemia should be investigated for thyroid dysfunction. Correction of hypokalemia improves acute presentation, but the patient will remain at risk for paralysis until euthyroid state is achieved.

Thyrotoxic Periodic Paralysis: An Incidental Diagnosis!

Thyrotoxic periodic paralysis is a rare presentation of thyrotoxicosis where the patient develops a transient motor deficit secondary to acute hypokalemia. The thyroid hormone augments gene transcription and post-transcriptional modification of Na-K ATPase, a cell membrane protein that regulates the electrical potential of the cell. Na-K ATPase increases active transport of potassium (K+) ions into the intracellular compartment causing hypokalemia without total body potassium deficit. Severe hypokalemia affects depolarization of the muscle cell membrane, clinically evidenced as paralysis. Other factors that may trigger hypokalemia and paralysis in the setting of hyperthyroidism include diet intake high in carbohydrates and salt, alcohol ingestion, trauma, infections, certain medication, and strenuous exercise. This rare but possible clinical presentation of thyrotoxicosis is significantly more predominant in males of Asian descent. We are reporting a case of a 44-year-old Asian-American male who presented to the emergency department with complaints of acute onset of bilateral lower extremity weakness. He had severe hypokalemia and was diagnosed with primary hyperthyroidism due to Graves' disease.

An atypical presentation of high potassium renal secretion rate in a patient with thyrotoxic periodic paralysis: a case report

Background

Hypokalemia is one of the most common clinical electrolyte imbalance problems, and thyrotoxic periodic paralysis (TPP) is a leading cause of presentation to the emergency department. Low renal potassium secretion rates, a normal acid–base balance in the blood, and hyperthyroidism are the hallmarks of suspected TPP.

Case presentation

Here we report the case of a 36-year-old man who presented to the emergency department with a sudden onset of acute muscle weakness at 5 h prior to admission. Biochemistry tests revealed hypokalemia with hyperthyroidism and renal potassium wasting. TPP was initially not favored due to the presence of renal potassium wasting. However, his serum potassium level rebounded rapidly within several hours after potassium supplementation, indicating that the intracellular shifting of potassium ions was the main etiology for his hypokalemia. The early stage of TPP development may have contributed to this paradox.

Conclusion

Therefore, it is premature to rule out TPP based on the presentation of high renal potassium secretion rates alone. This finding may result in an incorrect impression being made in the early stage of TTP and may consequently lead to an inappropriate potassium supplementation policy.

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

A case of thyrotoxic periodic paralysis with respiratory failure in an African American woman

Thyrotoxic periodic paralysis is an acute endocrine emergency characterized by hyperthyroidism, profound muscle weakness and/or paralysis, and hypokalemia that is not due to potassium deficiency. Typically described in young males of Asian descent, it is becoming increasingly recognized outside of this demographic group and is believed to be an underrecognized cause of symptomatic hypokalemia. Thyrotoxic periodic paralysis usually manifests as acute onset of symmetrical distal extremity weakness and is treated with careful potassium replacement and nonselective β-blockers. In this case, a 43-year-old African American woman with thyrotoxic periodic paralysis had recurrent lower extremity myopathy and acute respiratory failure precipitated by noncompliance with treatment for Graves disease.

The insulin-sensitivity sulphonylurea receptor variant is associated with thyrotoxic paralysis

Thyrotoxicosis is the most common cause of the acquired flaccid muscle paralysis in adults called thyrotoxic periodic paralysis (TPP) and is characterised by transient hypokalaemia and hypophosphataemia under high thyroid hormone levels that is frequently precipitated by carbohydrate load. The sulphonylurea receptor 1 (SUR1 (ABCC8)) is an essential regulatory subunit of the β-cell ATP-sensitive K(+) channel that controls insulin secretion after feeding. Additionally, the SUR1 Ala1369Ser variant appears to be associated with insulin sensitivity. We examined the ABCC8 gene at the single nucleotide level using PCR-restriction fragment length polymorphism (RFLP) analysis to determine its allelic variant frequency and calculated the frequency of the Ala1369Ser C-allele variant in a cohort of 36 Brazilian TPP patients in comparison with 32 controls presenting with thyrotoxicosis without paralysis (TWP). We verified that the frequency of the alanine 1369 C-allele was significantly higher in TPP patients than in TWP patients (61.1 vs 34.4%, odds ratio (OR)=3.42, P=0.039) and was significantly more common than the minor allele frequency observed in the general population from the 1000 Genomes database (61.1 vs 29.0%, OR=4.87, P<0.005). Additionally, the C-allele frequency was similar between TWP patients and the general population (34.4 vs 29%, OR=1.42, P=0.325). We have demonstrated that SUR1 alanine 1369 variant is associated with allelic susceptibility to TPP. We suggest that the hyperinsulinaemia that is observed in TPP may be linked to the ATP-sensitive K(+)/SUR1 alanine variant and, therefore, contribute to the major feedforward precipitating factors in the pathophysiology of TPP.

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.

Thyrotoxic periodic paralysis: clinical challenges

Thyrotoxic periodic paralysis (TPP), a disorder most commonly seen in Asian men, is characterized by abrupt onset of hypokalemia and paralysis. The condition primarily affects the lower extremities and is secondary to thyrotoxicosis. The underlying hyperthyroidism is often subtle causing difficulty in early diagnosis. Factors like high-carbohydrate meal exercise, steroid, and stress can precipitate an attack of TPP. Evidence is building up showing role of genetic mutations in Kir2.6 channel in the pathogenesis of TPP. Loss of function of Kir2.6 together with increased activity of Na(+)/K(+) ATPase may trigger a positive feed-forward cycle of hypokalemia. Biochemical hyperthyroidism with normal urinary potassium excretion and ECG changes are characteristic of TPP. Treatment with low-dose potassium supplements and nonselective beta-blockers should be initiated upon diagnosis, and the serum potassium level should be frequently monitored to prevent rebound hyperkalemia.

Thyroid disease and the nervous system

Thyroid disorders are common in the general population and in hospitalized patients. Thyroid disease may present first with neurological complications or else may occur concurrently in patients suffering other neurological disorders, particularly those with an autoimmune etiology. For this reason neurologists will commonly encounter patients with thyroid disease. This chapter provides an overview of the neurological complications and associations of disorders of the thyroid gland. Particular emphasis is placed on conditions such as thyrotoxic periodic paralysis and myxedema coma in which the underlying thyroid disorder may be occult leading to a first, often emergency, presentation to a neurologist. Information about clinical features, diagnosis, pathogenesis, therapy, and prognosis is provided. Emphasis is placed on those aspects most likely to be relevant to the practicing neurologist and the interested reader is directed to references to good, recent review articles for further information.

Iodine-induced thyrotoxic hypokalemic paralysis after ingestion of Salicornia herbace

A 56-year-old Korean man visited to emergency room due to paroxysmal flaccid paralysis in his lower extremities. There was no family or personal history of periodic paralysis. His initial potassium levels were 1.8 mmol/L. The patient had been taking Salicornia herbacea for the treatment of diabetes and hypertension. Results of a thyroid function test were as follows: T3 = 130.40 ng/dL, TSH = 0.06 mIU/L, and free T4 = 1.73 ng/dL. A thyroid scan exhibited a decreased uptake (0.6%). His symptoms clearly improved and serum potassium levels increased to 4.4 mmol/L by intravenous infusion of only 40 mmol of potassium chloride. Eight months after the discontinuation of only Salicornia herbacea, the patient's thyroid function tests were normalized. Large amounts of iodine can induce hypokalemic thyrotoxic paralysis and it may be necessary to inquire about the ingestion of iatrogenic iodine compounds, such as Salicornia herbacea.

Thyrotoxic periodic paralysis: clinical and molecular aspects

Thyrotoxic periodic paralysis (TPP) is a rare complication of hyperthyroidism that most often affects young East Asian males but increasingly also in other ethnic groups. The typical presentation is acute attacks varying from mild weakness to total paralysis starting at night or in the early morning a few hours after a heavy meal, alcohol abuse or strenuous exercise with complete recovery within 72 h. Signs and symptoms of hyperthyroidism may not be obvious. The hallmark is hypokalemia from increased cellular sodium/potassium-ATPase pump activity with transport of potassium from the extracellular to the intracellular space in combination with reduced potassium output. Recently, KCNJ18 gene mutations which alter the function of an inwardly rectifying potassium channel named Kir2.6 have been detected in 0-33 % of cases. Hence, the pathophysiology in TPP includes a genetic predisposition, thyrotoxicosis and environmental influences and the relative impact from each of these factors may vary. The initial treatment, which is potassium supplementation, should be given with caution due to a high risk of hyperkalemia. Propranolol is an alternative first-line therapeutic option based on the assumption that hyperadrenergic activity is involved in the pathogenesis. If thyroid function tests are unobtainable in the acute situation the diagnosis is supported by the findings of hypokalemia, low spot urine potassium excretion, hypophosphatemia with hypophosphaturia, high spot urine calcium/phosphate ratio, and electrocardiographic abnormalities as tachycardia, atrial fibrillation, high QRS voltage, and atrioventricular block. Definitive treatment is cure of the hyperthyroidism. The underlying mechanisms of TPP remain, however, incompletely understood awaiting further studies.

Pop-provoked paralysis: silent Graves' disease presenting as thyrotoxic periodic paralysis

A 48-year-old Filipino man presented after several episodes of worsening limb paralysis that occurred after drinking cola beverages. In the emergency department he was found to be hypokalaemic, and although he exhibited no symptoms of thyrotoxicosis he was biochemically hyperthyroid. Thyroid stimulating hormone receptor antibody serology was positive indicating Graves' disease as the underlying cause of his hyperthyroidism. Intravenous potassium supplementation resulted in complete resolution of symptoms, and a diagnosis of thyrotoxic periodic paralysis was made. He was started on a regimen of propylthiouracil and propranolol and subsequently given radioiodine as the definitive treatment for Graves' disease. There were no recurrent attacks of paralysis once a stable euthyroid state was achieved, and the patient was able to resume cola consumption without issue.

Levothyroxine and prednisone causing generalized weakness in a middle-aged man

Thyrotoxic induced hypokalemic periodic paralysis is a rare disorder that had been described in middle-aged men, predominantly Asians and Hispanics. This case presented with generalized weakness and hypokalemia after changing prescription for levothyroxine and starting prednisone to treat upper respiratory infection in a previously asymptomatic middle-aged Hispanic male. In this paper, we will go over the clinical presentation, mechanisms, and treatment of thyrotoxic induced hypokalemic periodic paralysis. Our objectives are to identify the classic constellation of findings in thyrotoxic periodic paralysis and to recognize the importance of considering thyrotoxic periodic paralysis among patients with hypokalemia.

Fatality after cardiac arrest in thyrotoxic periodic paralysis due to profound hypokalemia resulting from intravenous glucose administration and inadequate potassium replacement

BACKGROUND

Thyrotoxic periodic paralysis (TPP) is a variant of periodic paralysis (PP) that occurs in patients with underlying mutations in genes for cation channels, if they develop thyrotoxicosis. It is disabling, and fatalities sometimes occur. Here, we present a patient with TPP who developed hypokalemic paralysis that was probably aggravated by the administration of a carbohydrate, probably contributing to, if not causing, a fatal outcome.

SUMMARY

A 30-year-old Chinese patient received (131)I treatment for Graves' disease (GD) in our hospital. Three days later in the middle of the night, he developed aggravating paralytic symptoms after a heavy evening meal. The next morning, he was seen in a small clinic and was treated with 1250 mL 5% glucose containing 25 mL 10% potassium chloride (KCl). By early afternoon, he had not improved and was transferred to a city hospital, arriving with grade I muscle strength and severed facial and bulbar paralysis that was shortly followed by cardiac arrest with failure of resuscitation. Shortly before he died, his serum K(+) was 1.15 mEq/L (normal=3.5-5).

CONCLUSIONS

We postulate that severe hypokalemia developed in our patient in part in response to the high intravenous glucose load that he received. We advocate caution against using intravenous glucose solutions for potassium administration in patients with TPP and recommend a review of guidelines suggesting this form of treatment. In rural settings with limited resources, we favor oral potassium, not to exceed 100 mEq per day, and transfer to a modern medical facility in settings where muscle weakness is developing in patients with TPP.

Novel etiopathophysiological aspects of thyrotoxic periodic paralysis

Thyrotoxicosis can lead to thyrotoxic periodic paralysis (TPP), an endocrine channelopathy, and is the most common cause of acquired periodic paralysis. Typically, paralytic attacks cease when hyperthyroidism is abolished, and recur if hyperthyroidism returns. TPP is often underdiagnosed, as it has diverse periodicity, duration and intensity. The age at which patients develop TPP closely follows the age at which thyrotoxicosis occurs. All ethnicities can be affected, but TPP is most prevalent in people of Asian and, secondly, Latin American descent. TPP is characterized by hypokalemia, suppressed TSH levels and increased levels of thyroid hormones. Nonselective β adrenergic blockers, such as propranolol, are an efficient adjuvant to antithyroid drugs to prevent paralysis; however, an early and definitive treatment should always be pursued. Evidence indicates that TPP results from the combination of genetic susceptibility, thyrotoxicosis and environmental factors (such as a high-carbohydrate diet). We believe that excess T(3) modifies the insulin sensitivity of skeletal muscle and pancreatic β cells and thus alters potassium homeostasis, but only leads to a depolarization-induced acute loss of muscle excitability in patients with inherited ion channel mutations. An integrated etiopathophysiological model is proposed based on molecular findings and knowledge gained from long-term follow-up of patients with TPP.

Thyrotoxic Periodic Paralysis: Case Reports and an Up-to-Date Review of the Literature

Objectives. To describe 2 cases of thyrotoxic periodic paralysis. Methods. We report of 2 cases of thyrotoxic periodic paralysis in 2 individuals from 2 different backgrounds with emphasis on their presentation and treatment. We also conducted a literature search to put together an update review of thyrotoxic periodic paralysis. Results. A 47-year-old Chinese and 28-year-old Caucasian male presented with profound yet reversible weakness associated with hypokalemia on admission bloods and thyrotoxicosis. Both were given definitive therapy to prevent recurrence of attacks with any future relapse of thyrotoxicosis. Conclusion. Thyrotoxic periodic paralysis (TPP) is a rare but potentially serious complication of thyrotoxicosis resulting in temporary but severe muscle weakness. Recent discovery of a novel mutation in the KCNJ18 gene which codes for an inwardly rectifying potassium channel and is controlled by thyroid hormones may provide greater insight into the pathogenesis of TPP.

Hypokalemic thyrotoxic periodic paralysis with thyrotoxic psychosis and hypercapnic respiratory failure

Thyrotoxic periodic paralysis is a rare and potentially lethal neuromuscular disease that manifests as recurrent episodic muscle weakness associated with hypokalemia and thyrotoxicosis. Paralysis can rarely involve respiratory muscles leading to acute respiratory failure. The disease primarily affects people of Asian descent, but it is being increasingly reported in other ethnic groups. We review the literature and report a case of hypokalemic thyrotoxic periodic paralysis manifesting as thyroid storm with episodic acute respiratory failure requiring recurrent intubation and eventually requiring thyroidectomy for resolution of symptoms.

Analytic review: thyrotoxic periodic paralysis: a review

Thyrotoxic periodic paralysis (TPP) is an unusual complication of hyperthyroidism that frequently presents in a dramatic fashion, necessitating treatment in an emergency department or admission to an intensive care unit. Thyrotoxic periodic paralysis is characterized by transient, recurrent episodes of flaccid muscle paralysis affecting proximal more severely than distal muscles. Thyrotoxic periodic paralysis is most commonly a complication of Graves' disease in Asian males, although in recent decades, an increasing number of patients from all racial and ethnic backgrounds have been reported. Thyrotoxic periodic paralysis has a higher predilection for men than women despite the fact that thyroid disease is more frequently diagnosed in women. The presence of both hypokalemia and elevated levels of triiodothyronine (T3) and thyroxine (T4) are important diagnostic features during the acute episode. Treatment of TPP involves 2 steps, immediate action to reverse the paralysis followed by measures to prevent future attacks by restoration of a euthyroid state. Although the mainstay of treating an acute attack of TPP is correction of hypokalemia to avoid fatal cardiac arrhythmias and reverse muscle weakness, it must be appreciated by treating physicians that patients with TPP do not have a total body deficiency of potassium. Close attention must be given to potassium replacement as overly aggressive treatment can result in hyperkalemia. Correction of hypokalemia and the underlying thyrotoxic state usually results in amelioration of the acute attack. This review summarizes the epidemiology, clinical manifestations, pathogenesis, diagnosis, and treatment of TPP.

[Thyrotoxic periodic paralysis as a form of presentation of primary autoimmune hyperthyroidism: utility of non-selective beta blockers]

A 40-year-old Caucasian man presented to the emergency room of our hospital with bilateral lower extremity weakness with onset 1 hour previously and concurrent hypokalemia. After dramatic clinical progression for the first 5 hours, the episode resolved once serum potassium levels were normalized. Laboratory data revealed primary hyperthyroidism, indicating a diagnosis of thyrotoxic periodic paralysis (TPP). Treatment consisted of potassium, propranolol and methimazole administration. Although the mainstay of therapy is potassium replacement, the role of propranolol in improving the acute clinical manifestations of TPP has yet to be adequately clarified.