Does thyrotoxic periodic paralysis have a genetic predisposition? A case report

Case report: thyrotoxic periodic paralysis, an unusual cause of hypokalemia

Introduction: Thyrotoxic periodic paralysis (TPP) is a type of hypokalemic periodic paralysis that is caused by an underlying thyrotoxicosis. It is a rare cause of hypokalemia due to intracellular potassium shift, causing acute muscle weakness.Case presentation: We present a case of a 19-year-old male of Thai descent with acute proximal symmetric lower limb weakness. The combination of these symptoms with profound hypokalemia, rapid recovery after normalization of serum potassium, and evidence of hyperthyroidism led to the diagnosis of thyrotoxic periodic paralysis, in this case due to an underlying Graves' disease.Conclusion: Clinicians should consider the diagnosis of TPP when a patient presents with the triad of acute paresis, profound hypokalemia and hyperthyroidism.

Thyrotoxic Periodic Paralysis With Hypokalemia: A Case Study

Thyrotoxic periodic paralysis (TPP) is a rare life-threatening condition most commonly seen in individuals between the ages of 20-40 years. It is most prevalent in Hispanic and Asian populations. Here we present a case report of a young male patient admitted to our facility with an acute onset of paralysis. He was found to have new-onset hyperthyroidism and severe hypokalemia. TPP was exacerbated by the intake of a high-carbohydrate meal as well as a steroid injection within 24 hours of symptom onset.

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.

Glucocorticoid-Induced Hypokalemic Periodic Paralysis after Short-Term Use of Tenofovir with Hypophosphatemia: A Case Report

Hypokalemic periodic paralysis (HPP) is a neuromuscular disorder associated with muscular dysfunction caused by hypokalemia. There are various causes of HPPs and rarely, HPP appears to be relevant to tenofovir or glucocorticoid treatment. There have been several case reports of tenofovir-related nephrotoxicity or tenofovir-induced HPP. However, a case report of glucocorticoid-induced HPP in a patient using tenofovir temporarily has not been reported. Herein, we report a case of glucocorticoid-induced HPP with short-term use of tenofovir. A 28-year-old man visited the emergency room with decreased muscle power in all extremities (2/5 grade). In their past medical history, the patient was treated with tenofovir for two months for a hepatitis B virus infection. At the time of the visit, the drug had been discontinued for four months. The day before visiting the emergency room, betamethasone was administered at a local clinic for herpes on the lips. Laboratory tests showed hypokalemia, hypophosphatemia, and mild metabolic acidosis. However, urinalysis revealed no abnormal findings. Consequently, it can be postulated that this patient developed HPP by glucocorticoids after taking tenofovir temporarily. This is the first case report of glucocorticoid-induced HPP in a patient using tenofovir. Clinicians who prescribe tenofovir should be aware of HPP occurring when glucocorticoids are used.

Thyrotoxic Hypokalemic Periodic Paralysis Triggered by Dexamethasone Administration

Thyrotoxic hypokalemic periodic paralysis (THPP) is a disease characterized by recurrent episodes of muscle weakness due to intracellular potassium shifting in the presence of high levels of thyroid hormone. It occurs more commonly amongst young Asian men with underlying Graves' disease. Attacks are commonly precipitated by ingestion of carbohydrate-rich meals or alcohols, stress or strenuous exercise. Herein, we describe an adult Thai man suffering from a hypokalemic periodic paralysis attack after receiving a dexamethasone injection. The diagnosis of Graves' disease was confirmed by his thyroid function test and a presence of thyrotropin-receptor antibody. His weakness and hypokalemia responded well to potassium supplement and a non-selective beta blocker, while his thyrotoxicosis was initially controlled by an anti-thyroid medication and subsequently with a subtotal thyroidectomy. Clinicians should beware of this manifestation when administering steroids in the thyrotoxic patients, especially of Asian male descent.