Complete Heart Block during Potassium Therapy in Thyrotoxic Periodic Paralysis

A systematic review of the clinical characteristics and course of atrioventricular blocks in hyperthyroidism

BACKGROUND

Atrioventricular block (AVB) is rare in hyperthyroidism (HTH). Little is known about the true prevalence, clinical course, optimal management, and outcomes of different types of AVBs in patients with HTH. To address these uncertainties, we aimed to conduct a systematic review by combining the available literature to provide more meaningful data regarding AVBs in HTH.

METHODS

We systematically searched PubMed, Scopus, Embase, and Google Scholar for articles reporting patients who developed AVB in the context of HTH. Data were analysed in STATA 16. The main outcomes included types of AVB, frequency of pacemaker insertion, and resolution of AVB. The systematic review is registered with the International Prospective Register of Systematic Reviews (PROSPERO) with the identification number CRD42022335598.

RESULTS

A total of 56 studies (39 case reports, 12 case series, 3 conference abstracts, 1 retrospective study, and 1 prospective observational study) with 87 patients were included in the analysis, with a mean age of 39.1 ± 17.6 years. Females constituted 65.7% (n = 48) of the cohort. Complete heart block (CHB) was the most commonly reported AVB (N = 45, 51.7%), followed by first-degree AVB (16.1%) and second-degree AVB (14.9%). Overall, 21 patients underwent pacing. A permanent pacemaker was inserted in one patient with second-degree AVB and six patients with CHB. Mortality was reported in one patient with CHB. The clinical course and management of HTH and AVBs did not differ in patients with CHB or lower-degree blocks. Apart from lower rates of goitre and more use of carbimazole in those who underwent pacing, no differences were found when compared to the patients managed without pacing.

CONCLUSION

Current data suggest that CHB is the most common type of AVB in patients with HTH. Most patients can be managed with anti-thyroid management alone. Additionally, whether pacemaker insertion alters the clinical outcomes needs further exploration.

A Thyrotoxic Periodic Paralysis Case Study: From Weakness to Wellness

Hypokalaemic periodic paralysis (HPP) is a rare disorder characterized by episodic attacks of muscle weakness and hypokalaemia. Numerous factors contributing to HPP have been identified, encompassing both hereditary and familial origins as well as acquired factors. In this context, we highlight thyrotoxicosis causing HPP. We present a case of a 40-year-old Asian individual who presented with episodes of sudden onset bilateral proximal limb weakness and palpitations. Laboratory investigations revealed severe hypokalaemia (serum potassium: 1.8 mmol/L). Immediate potassium replacement therapy alleviated symptoms. Further evaluation revealed a new diagnosis of hyperthyroidism, with subsequent treatment initiated (carbimazole and propranolol) preventing recurrence of symptoms. This case highlights the importance of recognizing HPP as a potential manifestation of thyroid dysfunction, particularly in individuals of Asian ethnicity.

Case report: Hyperthyroid hypokalemic periodic paralysis

Introduction and importance

HHPP is a rare type of hypokalemic PP that can occur when there is hyperthyroidism.Thyrotoxic periodic paralysis is due to increased influx of potassium into skeletal muscle cells which leads to profound hypokalemia and paralysis. Insulin and Epinephrine are also responsible for stimulating the Na–K-ATPase pumps which are over expressed during hyperthyroid state. Laboratory hypokalemia in the background of hyperthyroidism with sudden symmetric paralysis point toward the diagnosis.

Case

We present a case of 25 year old male with limb weakness for 3hours following heavy dinner.He felt weakness after waking up in the morning where he could not move his both lower limbs. He also had difficulty moving upper limbs.

Clinical findings and investigations

Examination revealed proximal muscle weakness with power of 2/5, decreased muscle tone, diminished deep tendon reflexes in all four limbs and equivocal plantar reflex bilaterally. Investigation sent were Total Leukocyte count, Hemoglobin, Renal function test, Liver Function test,Thyroid function test, Vitamin B12, Serology, ACTH, Serum calcium, Serum phosphate, Serum magnesium, Urine R/ME and Stool R/ME.

Intervention and outcome

Patient is treated with 10mEq/L/hr infusion of potassium chloride, methimazole and beta-blockers. He is stable and is in regular followup in medicine OPD.

Relevance and impact

Early diagnosis of HHPP is very essential to prevent fatal complications (cardiac and respiratory).

It can be treated by timely potassium supplementation, methimazole and beta-blockers.

Clinicians must be concerned about Hyperkalemia while supplementing Potassium in bed side.

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HHPP is a rare life-threatening complication of hyperthyroidism which is characterized by episodes of acute muscle weakness due to hypokalemia.

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Periodic paralysis (PP) is a muscle disease, characterized by episodes of painless muscle weakness. These episodes can be triggered by strenuous exercise, fasting, or consuming high-carbohydrate foods.

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Treatment cand be done by potassium supplementation until normalized serum potassium level. Patient must be kept in cardiac monitoring and serum potassium monitoring.

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Hyperthyroidism can be treated with methimazole. Patient must be kept under regular follow up in endocrinology department.

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Relapses can be prevented by treatment with radioactive iodine or surgery. Beta-blocking drugs have also been proven to reduce the frequency and severity of episodes.

"I'm so weak I feel paralyzed. Can you help me?" A case on thyrotoxic periodic paralysis

Thyrotoxic periodic paralysis (PP) is a rare condition characterized by muscle weakness in the form of hyperthyroidism and hypokalemia. We present the case of a 38-year-old Hispanic male with PP that had been occurring over the course of 4 years. After several emergency department visits, the cause of his symptoms was still unknown. Initial laboratory testing revealed critical hypokalemia with associated electrocardiogram (ECG) changes. Further laboratory evaluation revealed hyperthyroidism, and the diagnosis of thyrotoxic PP was made. The patient received potassium supplementation with complete resolution of his symptoms and resolution of pathologic ECG changes. Our patient was started on propranolol and methimazole to treat his hyperthyroidism. Not well documented in previous reports, we stress the importance of using serial ECGs as an adjunct to patient improvement.

Graves' Disease Presenting with Complete Atrioventricular Block

Hyperthyroidism commonly causes tachyarrhythmias such as sinus tachycardia and atrial fibrillation. Impaired atrioventricular conduction is a very rare complication of hyperthyroidism. We report a case of a patient with hyperthyroidism due to Graves' disease presenting with syncope and complete atrioventricular block. Because lack of awareness of atypical presentation in patients with hyperthyroidism may delay diagnosis and treatment, the recognition that hyperthyroidism can be one of the reversible causes of complete atrioventricular block is important.

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.

Normokalemic Thyrotoxic Periodic Paralysis with Acute Resolution in the Emergency Department

Thyrotoxic periodic paralysis is a rare cause of acute paralysis in the emergency department (ED). The disorder is generally thought to be due to acute hypokalemia leading to paralysis. Treatment is generally targeted at correcting the thyrotoxic state with careful potassium repletion. We present a rare case of normokalemic, thyrotoxic periodic paralysis with acute resolution while in the ED.

A Case of Nonfatal Ventricular Arrhythmia Due to Thyrotoxic Periodic Paralysis in a Saudi Patient as an Initial Presentation of Graves' Disease

Thyrotoxic periodic paralysis (TPP) is a potentially lethal complication of hyperthyroidism characterized by recurrent muscle weakness and hypokalemia. It has been commonly reported in non-Asian populations. Four cases were reported in Saudis so far, and one had a life-threatening arrhythmia. We describe an additional case of a 28-year-old apparently healthy Saudi male patient, who presented with acute paraparesis associated with hypokalemia (K: 2.0 mmol/L), complicated by ventricular tachycardia and cardiac arrest. He was successfully resuscitated and his hypokalemia was corrected. A diagnosis of Graves’ disease associated with TPP was made. He was initially treated with carbimazole and β-blockers and then given a definitive therapy with radioactive iodine, which showed a good response. This case highlights the importance of early recognition and prompt treatment of TPP as a differential diagnosis for muscle weakness. A brief review of TPP and associated arrhythmia is included.

Etiologic and therapeutic analysis in patients with hypokalemic nonperiodic paralysis

BACKGROUND

Hypokalemic nonperiodic paralysis represents a group of heterogeneous disorders with a large potassium (K(+)) deficit. Rapid diagnosis of curable causes with appropriate treatment is challenging to avoid the sequelae of hypokalemia. We prospectively analyzed the etiologies and therapeutic characteristics of hypokalemic nonperiodic paralysis.

METHODS

Over an 8-year period, patients with hypokalemic nonperiodic paralysis were enrolled by excluding those with hypokalemic periodic paralysis due to acute shift of K(+) into cells. Blood and spot urine samples were collected for the measurements of electrolytes, pH, and biochemistries. Intravenous potassium chloride (KCl) at a rate of 10-20 mmol/h was administered until muscle strength recovered.

RESULTS

We had identified 58 patients with hypokalemic nonperiodic paralysis from 208 consecutive patients with hypokalemic paralysis, and their average K(+) concentration was 1.8 ± 0.2 mmol/L. Among patients with low urinary K(+) excretion (n = 17), chronic alcoholism, remote diuretic use, and anorexia/bulimia nervosa were the most common causes. Among patients with high urinary K(+) excretion (n = 41) and metabolic acidosis, renal tubular acidosis and chronic toluene abuse were the main causes, while primary aldosteronism, Gitelman syndrome, and diuretics were the leading diagnoses with metabolic alkalosis. The average KCl dose needed to restore muscle strength was 3.8 ± 0.8 mmol/kg. Initial lower plasma K(+), volume depletion, and high urinary K(+) excretion were associated with higher recovery KCl dosage. During therapy, patients with paradoxical hypokalemia (n = 32) who required more KCl supplementation than patients without (4.1 ± 0.7 vs 3.4 ± 0.7 mmol/kg, P < 0.001) often exhibited significantly higher plasma renin activity and received a higher volume of normal saline before its appearance.

CONCLUSIONS

Understanding the common etiologies of hypokalemic nonperiodic paralysis may aid in early diagnosis. Patients with initial lower plasma K(+), renal K(+) wasting, and hypovolemia required higher recovery K(+) dosage. Paradoxical hypokalemia is prone to develop in hypovolemic patients even during K(+) supplementation with volume repletion.