Case of thyrotoxic periodic paralysis in a caucasian male and review of literature

Thyrotoxic periodic paralysis in a Caucasian man without identifiable genetic predisposition: a case report

BACKGROUND

Thyrotoxic periodic paralysis (TPP) is a rare condition characterized by muscle paralysis, thyrotoxicosis, and hypokalemia. It presents with paralysis of both proximal and distal musculature in upper and lower limbs and may affect respiratory musculature and the cardiac conduction system. Early diagnosis is essential, as the condition is potentially reversible by oral or intravenous potassium treatment, leading to rapid resolution without lasting weakness. Overlooking the diagnosis may result in respiratory failure and cardiac arrhythmias including QT prolongation, Torsades de points, and ventricular arrhythmias.

CASE PRESENTATION

A 19-year-old Caucasian man was admitted acutely with paralysis in upper and lower limbs and tachycardia. Over several months, he had experienced anxiousness, sweating more than usual, had daily palpitations, shortness of breath on exertion, and loose stools, and had lost 21 kg over the last year. Initial blood gas showed very low potassium of 1.4 mM, and blood tests showed decreased Thyroid-stimulating hormone (TSH) < 0.01 × 10^- 3 IU/L, elevated free thyroxine (fT4) of 63.5 pM (reference interval (RI): 12.0-22.0 pM), and elevated total triiodothyronine (T3) of 8.2 nM (RI: 1.0-2.6 nM). He was diagnosed with TPP and treated with liquid oral potassium chloride (30 mmol every 30 minutes) and propylthiouracil (initial dose of 400 mg followed by 200 mg three times daily). TSH-receptor antibodies (TRAB) and thyroid-peroxidase antibodies (TPO-ab) were highly elevated. Thyroid ultrasound showed a normal-sized gland and color Doppler sonography showed increased vascularity throughout the gland, compatible with Graves' disease. He was discharged on day 4 with a normal potassium level and followed in the outpatient clinic where he received standard care for Graves' disease. Genetic testing using whole-genome sequencing found no genetic variants in genes previously associated with TPP.

CONCLUSION

TPP is very rare in Caucasians but more often affects young men in East Asian populations. The case presents a Caucasian man with TPP where genetic testing of CACNA1S, KCNJ18, SCN4A, KCNJ2, KCNE3, and ABCC8 shows no pathogenic variants in genes previously associated with TPP.

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.

Thyrotoxic Periodic Paralysis with Sensory Deficits in Young African American Male: A Case Report and Literature Review

Thyrotoxic periodic paralysis is a sporadic entity characterized by hypokalemia and paralysis in the setting of hyperthyroidism. TPP is most commonly described in young Asian males. Studies have shown an association with mutations affecting inward rectifying potassium channels. The pathophysiology involves Na⁺-K⁺- ATPase channel causing an increased intracellular shift of potassium ions in the hyperthyroid state and in the presence of another precipitating condition. Most cases of thyrotoxic periodic paralysis are defined in young Asian males of 20–40 years of age, here we present an interesting case of thyrotoxic periodic paralysis in 32-year-old African American male, who presented with sudden onset weakness in the bilateral lower extremity and left upper extremity. Interestingly, the patient also has sensory deficits, a feature not known to be associated with thyrotoxic periodic paralysis.

Periodic Paralysis and Encephalopathy as Initial Manifestations of Graves' Disease: Case Report and Review of the Literature

BACKGROUND

Thyrotoxic periodic paralysis (TPP) is an uncommon complication of Graves' disease, characterized by the triad of acute hypokalemia without total body potassium deficit, episodic muscle paralysis, and thyrotoxicosis. Graves' encephalopathy is an extremely rare form of encephalopathy associated with autoimmune thyroid disease (EAATD), characterized by neuropsychiatric symptoms, increased antithyroid antibodies and cerebrospinal fluid protein concentration, nonspecific electroencephalogram abnormalities, and cortico-responsiveness. Coexistence of both these complications in the same patient has not been reported before.

CASE REPORT

We herein present a 48-year-old white male patient with TPP and encephalopathy as initial presentations of Graves' disease. Flaccid tetraparesis was reversed a few hours after potassium level correction and the patient did not suffer any relapse with the successful pharmaceutical management of the thyroid function. One month later, the patient presented with dizziness and behavioral symptoms, such as inappropriate laughter and anger. Brain magnetic resonance imaging revealed meningeal enhancement and cerebrospinal fluid analysis showed a mild protein increase, with a blood-brain barrier disruption. With the suspicion of EAATD, the patient was treated with high doses of corticosteroids and improved dramatically.

CONCLUSIONS

To our knowledge this is the first reported coexistence of potentially treatable TPP and EAATD as initial neurological manifestations of Graves' disease, thereby underscoring the necessity of suspicion of possible underlying Graves' disease in patients with acute paralysis and encephalopathy of unclear origin.