Case Presentation: A twenty-year-old male patient with no past medical history presented to the emergency department with bilateral lower extremity weakness after working in agricultural fields which had progressed over three hours to near paralysis. When the patient was first evaluated, an ECG revealed his heart rhythm to be in asymptomatic ventricular tachycardia. He exhibited minor dyspnea at the time and was started on a magnesium drip in response to hypomagnesemia. While initiated on the drip, his rhythm exhibited ventricular fibrillation and a code was initiated where the patient was defibrillated three times. The patient achieved return of spontaneous circulation and was sedated and intubated. His potassium was found to be reduced to 1.7 at the time. He was started on a potassium infusion, but successive potassium labs continued to be extremely low. Thyrotoxic periodic paralysis (TPP) was added to the differential and the patient was started on propylthiouracil and corticosteroids while a TSH and T4 was sent to the lab. The patient’s electrolyte abnormalities self-corrected and his paralysis resolved within a matter of hours. The patient was extubated two days later, and a diagnosis of TPP was confirmed via lab and it was revealed that he had four family members with thyroid disease. Unfortunately, his course was then complicated by a left M2 occlusion noted after expressive aphasia, left gaze deviation, and right sided weakness. He was taken for emergent thrombectomy with TICI 2b recanalization but suffered lasting neurologic effects.
Discussion: TPP is a known complication of thyrotoxicosis that is mainly seen in young, male Asian or Hispanic populations. TPP cases have been increasing in the US over the past ten years, with numerous published cases indicating the disease is less rare than previously thought. Symptoms range from transient episodes of weakness to complete flaccid paralysis, mainly affecting the proximal muscles. The attacks of weakness generally occur after a large meal or rest after strenuous exercise or work, such as in our patient. The hallmark of TPP is hypokalemia due to massive shift into the cells without urinary or fecal potassium loss. This internal cellular shift can be seen with magnesium as well, which could account for his low levels on presentation and requirement of magnesium drip. Treatment includes potassium replacement (being careful not to cause rebound hyperkalemia), propylthiouracil, propranolol, and glucocorticoids to decrease the release of T3 and T4 from the thyroid as well as inhibit peripheral conversion to T3. This case was a good catch, though came with an unfortunate ending due to neurologic complications.
Conclusions: Paralysis is an alarming presenting symptom in for any patient. Thyrotoxic periodic paralysis is a rare, and often delayed, diagnosis that can be life threatening if missed. As noted in this paper, TPP is an increasingly identified condition noted in Hispanic and Asian populations within the United States and increasing awareness through vignettes such as this is vital to improving care and outcomes of this condition.