Factitious thyrotoxicosis is the presence of excess circulating thyroid hormone from an exogenous source. It can be iatrogenic or it can occur due to intentional thyroid hormone misuse or abuse. It can also occur due to accidental ingestion, pharmacy error, or inadvertent exposure to unlabeled thyroid hormone in supplements or contaminated hamburger meat. Consequences range from mild thyrotoxic symptoms to more serious or life-threatening sequelae including thyrotoxic periodic paralysis, seizure, coma, arrhythmias, myocardial infarction, and thyroid storm. If unclear from the history, differentiating factitious thyrotoxicosis from other etiologies of thyroid hormone excess is challenging, and may require radioactive iodine uptake and serum thyroglobulin testing. In most cases, treatment simply consists of stopping the exogenous thyroid hormone exposure with subsequent monitoring. However, in cases of massive acute poisoning with thyroid hormone, gastric decontamination strategies and inpatient care in a monitored setting with measures to reduce circulating T3 levels may be needed.

Thyrotoxic periodic paralysis (TPP) is a reversible but potentially severe complication of thyrotoxicosis characterized by acute muscle weakness and hypokalemia resulting predominantly from intracellular potassium redistribution. Although classically associated with Asian populations, TPP is increasingly recognized in Latin America. We report a 38-year-old Colombian man with recurrent nocturnal proximal quadriparesis, preserved deep tendon reflexes, serum potassium of 2.3 mEq/L, and biochemical thyrotoxicosis secondary to Graves disease. In parallel, we conducted a structured review of published Colombian cases identified through searches of PubMed/MEDLINE, Scopus, Web of Science, SciELO, and Google Scholar from inception through 1 May 2026. Fourteen previously published cases were identified, yielding 15 cases including the index patient. All patients were male, with a mean age of 31.4 ± 7.4 years. Deep tendon reflexes were normal in 4/13 (30.8%) cases in which they were documented, demonstrating that preserved reflexes do not exclude TPP. TSH was suppressed below 0.05 mIU/L in 14/15 (93.3%) patients. Electrocardiographic findings were reported in only 7/15 cases, and antithyroid drug doses in 6/15, highlighting substantial heterogeneity in reporting. All reported patients recovered muscle strength following acute management. TPP should therefore be considered in patients presenting with acute proximal weakness and hypokalemia even when deep tendon reflexes are preserved or overt manifestations of thyrotoxicosis are absent. Standardized reporting of biochemical, electrocardiographic, therapeutic, and follow-up data is needed to improve characterization of TPP in underrepresented populations.

Distal renal tubular acidosis (dRTA) is associated with autoimmune disorders, particularly Sjögren's syndrome. Hypokalemic muscle weakness due to dRTA is an uncommon presentation of Sjögren's syndrome and may mimic primary hypokalemic periodic paralysis, resulting in a diagnostic delay. We present the case of a 35-year-old woman who reported recurrent limb weakness in the presence of hypokalemia (serum potassium: 2.7 mmol/L). She had previously been diagnosed with primary hypokalemic periodic paralysis, but this diagnosis was challenged as she was found to have normal anion gap metabolic acidosis and an alkaline urine pH with significant potassium wasting. The patient reported the presence of subtle sicca symptoms only on direct questioning. Further workup revealed positive serology for Sjögren's syndrome. She was managed with potassium and sodium bicarbonate replacement and given oral steroids and azathioprine for long-term management. Following correction of electrolyte abnormalities, the patient's muscle strength improved significantly, and she regained functional mobility. Her metabolic acidosis also resolved, and she experienced no further episodes of weakness or electrolyte imbalance during 12 months of follow-up. Primary Sjögren's syndrome-associated distal RTA should be considered in patients presenting with recurrent hypokalemic paralysis, particularly in the presence of normal anion gap metabolic acidosis and alkaline urine pH. Early treatment prevents recurrent paralysis and long-term renal complications.

Hypokalemic periodic paralysis (HypoPP) is an inherited skeletal muscle ion channelopathy of CACNA1S or SCN4A characterized by recurrent episodes of weakness, often triggered by rest after exercise or by reduced K+ (carbohydrate ingestion, stress). Here, we describe a multigenerational family in whom a KCNA7 missense variant [c.834A>C (p.Arg278Ser)] co-segregated with susceptibility to recurrent attacks of weakness in association with hypokalemia as low as 1.3 mEq/L and a 40% decrement of the compound muscle action potential after exercise, suggesting an additional HypoPP gene. Arg278 is the outermost positively charged residue (R1) within the S4 transmembrane segment of the voltage-sensor domain of K V 1.7, orthologous to the canonical patten of arginine missense mutations at R1 or R2 in S4 segments for HypoPP-mutant Ca V 1.1 and Na V 1.4 channels. To determine the functional consequences of Arg278Ser, we expressed wild-type and mutant K V 1.7 channels in Xenopus oocytes and HEK293 cells. Arg278Ser, but not wild-type K V 1.7, generated an anomalous inwardly rectifying current at hyperpolarized membrane potentials that was nonselective Na [+] or K [+] , consistent with the anomalous gating pore conductance that causes susceptibility to HypoPP. Other pathogenic variants of KCNA7 have previously been implicated only in inherited cardiac arrhythmias. Collectively, the genetic, structural and electrophysiological findings support KCNA7 Arg278Ser as a pathogenic variant underlying HypoPP and implicate KCNA7 as a disease gene for periodic paralysis, extending the established gating-pore mechanism of HypoPP to K V 1.7.

Hypokalemic periodic paralysis (HypoPP) is an autosomal dominant disorder caused by a p.Arg528His mutation in the CACNA1S gene, which encodes the α1-subunit of the skeletal muscle L-type calcium channel. The mutation causes leaky ion flow and impairs muscle excitation-contraction coupling. Patients exhibit episodic paralysis, muscle attacks, and hypokalemia. Two human induced pluripotent stem cell (iPSC) lines were generated from HypoPP patients, SCVIi152-A and SCVIi153-A, each carrying the CACNA1S c.1583G>A (p.Arg528His) mutation. Both lines exhibited pluripotency marker expression at gene and protein levels, displayed a normal karyotype, and differentiated into all three germ layers in vitro. These lines are valuable resources for modeling HypoPP.

Andersen-Tawil syndrome is a rare autosomal dominant multisystem disorder characterized by ventricular arrhythmias, periodic paralysis, and dysmorphic features. However, marked phenotypic heterogeneity is observed, contributing to significant diagnostic delays. Andersen-Tawil syndrome is most commonly caused by loss-of-function variants in KCNJ2, which encodes the α-subunit of the inward rectifier potassium channel Kir2.1, resulting in impaired IK1 currents. Impaired IK1 destabilizes terminal repolarization and depolarization kinetics, promoting prominent U waves, ventricular ectopy, and complex ventricular arrhythmias. Management remains challenging owing to limited evidence and variable treatment responses. β-Blockers and flecainide are commonly used, whereas implantable cardioverter defibrillators are reserved for high-risk cases. Potassium supplementation and acetazolamide should be considered in selected patients with periodic paralysis. Given the incomplete penetrance and the absence of validated risk stratification tools, careful multidisciplinary evaluation and individualized management are essential.

A 56-year-old man with a family history of myopathy developed generalized muscle weakness at age 45. At age 52, he was diagnosed with inclusion-body myopathy with Paget disease of bone and frontotemporal dementia (IBMPFD), confirmed by muscle pathology and a pathogenic VCP mutation (c.464G>A, p.R155H). Concurrent testing identified a heterozygous SCN4A variant (c.215C>T, p.P72L), a known modifier in myotonic dystrophy type 2 (DM2). At age 56, neurological examination showed proximal muscle weakness (MMT grade 3), distal lower extremity weakness (grade 4-5), and areflexia. He ambulated independently with knee locking, though squatting was impossible. No myotonia or periodic paralysis was observed. Multimodal imaging captured classic IBMPFD hallmarks: skeletal muscle computed tomography (CT) showed advanced fatty degeneration of paraspinal and limb muscles; brain magnetic resonance imaging (MRI) revealed mild frontal lobe atrophy; and bone scintigraphy showed increased uptake in the lumbar spine and iliums. Although the SCN4A p.P72L variant exacerbates DM2, the patient's three-year progression from independent walking to cane use remained consistent with the natural history of IBMPFD. This case suggests that in the presence of a robustly penetrant VCP phenotype, the SCN4A variant does not necessarily exert a clinical modifying effect.

A rare late-onset presentation of episodic weakness associated with hyperkalemia is described in a 72-year-old male with concurrent early-stage chronic lymphocytic leukemia. He experienced frequent episodes of generalized muscle weakness accompanied by loss of speech, shortness of breath, and fatigue, with a documented serum potassium level of 6.5 mmol/L obtained within 30 minutes of an attack. Treatment with acetazolamide and dietary modification was associated with a substantial reduction in episode frequency and improved functional status, although persistent fatigue remained. The clinical presentation was suggestive of hyperkalemic periodic paralysis, but a definitive diagnosis was limited by the patient's exceptionally late age at onset, negative genetic testing, lack of specialized exercise testing, and absence of electrophysiologic testing during an attack. This case emphasizes the importance of considering hyperkalemic periodic paralysis in the differential diagnosis of episodic weakness while simultaneously evaluating alternative neuromuscular, metabolic, hematologic, and paraneoplastic causes. Treatment response to acetazolamide and dietary modification was considered supportive of but not necessarily diagnostic of an inherited channelopathy.

Acute flaccid paralysis (AFP) in adults is a clinical emergency with multiple causes, including hypokalemic periodic paralysis (hypoPP), Guillain-Barré syndrome (GBS), myasthenia gravis (MG), and botulinum neurotoxin (BoNT) poisoning. Herein, we present the case of a 64-year-old Asian man who ingested an unidentified fish. Within 30 minutes of ingestion, he developed flaccid paralysis along with gastrointestinal symptoms and perioral tingling. After 3 hours, his condition deteriorated to worsening respiratory distress and unconsciousness, requiring mechanical ventilation for one week. Blood and urine samples tested positive for 11-norTTX-6-ol, a tetrodotoxin (TTX) analog. Cytochrome b (Cytb) gene analysis of the remaining consumed fish revealed that the fish was Lagocephalus lunaris. Although TTX poisoning is rare, some countries have relatively high rates due to regional factors. When immediate laboratory confirmation is not possible, analysis of patient clinical history is crucial for diagnosis. Because this condition progresses rapidly, prompt stabilization of vital signs by clinicians increases the likelihood of survival and reduces the risk of death.

Hypokalemic periodic paralysis (HypoKPP) is a rare channelopathy that typically presents in adolescence with recurrent episodes of muscle weakness triggered by factors that lower serum potassium. We report a 37-year-old Japanese male with genetically confirmed HypoKPP caused by the rare SCN4A p.Arg672Cys variant. Despite late onset (early 30s) and infrequent attacks, the patient presented with classic flaccid paralysis and severe hypokalemia (1.8 mEq/L) triggered by exercise, alcohol consumption, and carbohydrate intake. Genetic testing confirmed the diagnosis after the condition was initially misattributed to insulin-related hypokalemia. This case highlights the importance of considering HypoKPP in adults with new-onset weakness and unexplained hypokalemia, even in atypical presentations characterized by late onset and infrequent attacks.

Thyrotoxic periodic paralysis (TPP) is a rare but life-threatening cause of acute flaccid paralysis associated with hypokalemia. Although more common in males and individuals of Asian descent, it may present atypically in young females and be easily misdiagnosed. We report a case of a 30-year-old female who presented with acute quadriparesis. Extensive neuromuscular evaluation initially pointed toward Guillain-Barré syndrome (GBS), but subsequent investigations revealed profound hypokalemia. Further workup confirmed thyrotoxicosis as the underlying cause. Prompt potassium replacement and initiation of antithyroid therapy led to complete clinical recovery. This case highlights the importance of considering both endocrine disorders and electrolyte disturbances, such as hypokalemia, in the differential diagnosis of acute paralysis.

This clinical case report involves a 34-year-old male patient with a history of type 2 diabetes and schizophrenia, who took oral olanzapine for a long time and visited the hospital several times because of lower limb fatigue caused by hypokalemia. Although the symptoms were alleviated by potassium supplementation, they recurred. The patient was hospitalized because of hypoglycemia and fatigue. Laboratory examination revealed hypokalemia, After supplementing potassium, the symptoms gradually eased. To prevent the patient from experiencing hypokalemia again, we asked about his diet and found that he had an unbalanced diet with a lot of cola consumption. To confirm that heavy cola drinking and an unbalanced diet might be related to hypokalemic periodic paralysis, we advised the patient to stop drinking cola and maintain a balanced diet. Follow-up studies showed that after stopping cola and eating a balanced diet, the patient did not experience hypokalemia again. This suggests that drinking a lot of cola is related to episodes of hypokalemic periodic paralysis. Therefore, when doctors encounter patients with hypokalemic periodic paralysis in routine practice, they should pay attention to the patient's eating habits during consultations to avoid missing a diagnosis and recurrence.