Thyrotoxic Hypokalemic Periodic Paralysis Induced by High-Dose Insulin in an Adolescent Male with Type 1 Diabetes Mellitus.

Introduction: Thyrotoxic hypokalemic periodic paralysis (THPP) is a rare but severe complication of hyperthyroidism characterized by acute muscle weakness. This study reports the first case of THPP in an adolescent with type 1 diabetes mellitus (T1DM) and Graves' disease, triggered by high-dose insulin, high carbohydrate intake, and strenuous exercise. It highlights the clinical presentation, management, and implications of THPP in this context.

Case presentation: A 17-year-old male patient with T1DM and Graves' disease presented to the emergency department with weakness in the extremities. The patient had engaged in strenuous exercise and high-dose rapid-acting insulin, and consumed a large amount of rice shortly before the onset of the symptoms. He exhibited hypertension and tachycardia, with diminished muscle strength and deep tendon reflexes with severe hypokalemia (1.6 mmol/L). Treatment with potassium and magnesium replacements was initiated. The patient's symptoms resolved within 5 h, and his neurological examination was normalized. Hypokalemia did not recur during follow-up. All symptoms improved rapidly with potassium replacement, β-blocker therapy, and antithyroid treatment.

Conclusion: This case represents the first documented instance of THPP in an adolescent with T1DM and Graves' disease. This entity should be included in the differential diagnosis of acute paralysis in patients with known thyrotoxicosis or those exhibiting symptoms such as tachycardia and hypertension. Insulin treatment in a hyperthyroid diabetic patient may increase the risk of THPP.